Resume Preparation Guidelines Interview question

Before even the interviewer meets you he will first meet your resume. Interviewer looking at your resume is almost a 20% interview happening with out you knowing it. I was always a bad guy when it comes to resume preparation. But when I looked at my friend’s resume they where gorgeous. Now that I am writing series of book on interviews I thought this will be a good point to put in. You can happily skip it if you are confident about your resume. There is no hard and fast rule that you have to follow the same pattern but just see if these all check list are attended.

Use plain text when you are sending resumes through email. For instance you sent your resume using Microsoft word and what if the interviewer is using Linux he will never be able to read your resume. You can not be sure both wise, you sent your resume in Word 2000 and the guy has Word 97.

Attach a covering letter it really impresses and makes you look traditionally formal. Yes, even if you are sending your CV through email send a covering letter. Check list of content you should have in your resume:-

• Start with an objective or summary, for instance, “Working as a Senior Database administrator for more than 4 years. Implemented quality web based application. Follow the industry’s best practices and adhered and implemented processes, which enhanced the quality of technical delivery. Pledge to deliver the best technical solutions to the industry.”
• Specify your Core strengths at the start of the resume by which the interviewer can make a quick decision are you eligible for the position. For example :-

1. Looked after data mining and data warehousing department independently. Played a major role in query optimization.
2. Worked extensively in database design and ER diagram implementation.
3. Well versed with CMMI process and followed it extensively in projects.
4. Looking forward to work on project manager or senior manager position. This is also a good position to specify your objective or position which makes it clear to the interviewer that should he call you for an interview. For instance, if you are looking for senior positions specify it explicitly ‘looking for this job profile’. Any kind of certification like MCP, MCSD etc you can make it visible in this section.60

• Once you have specified briefly your goals and what you have done its time to specify what type of technology you have worked with. For instance RDBMS, TOOLS, Languages, Web servers, process (Six sigma, CMMI).
• After that you can make a run through of your experience company wise that is what company you have worked with, year / month joining and year / month left. This will give an overview to the interviewer what type of companies you have associated your self. Now its time to mention all your projects you have worked till now. Best is to start in descending order that is from your current project and go backwards. For every project try to put these things :-

• Project Name / Client name (It’s sometimes unethical to mention clients name; I leave it to the readers).
• Number of team members.
• Time span of the project.
• Tools, language, RDBMS and technology used to complete the project.
• Brief summary of the project. Senior people who have huge experience will tend to increase there CV with putting in summary for all project. Best for them is to just put description of the first three projects in descending manner and rest they can say verbally during interview. I have seen CV above 15 pages… I doubt who can read it.
• Finally comes your education and personal details.
• Trying for onsite, do not forget to mention your passport number.
• Some guys tend to make there CV large and huge. I think an optimal size should be not more than 4 to 5 pages.
• Do not mention your salary in CV. You can talk about it during interview with HR or the interviewer.
• When you are writing your summary for project make it effective by using verbs like managed a team of 5 members, architected the project from start to finish etc. It brings huge weight.
• This is essential very essential take 4 to 5 Xerox copies of your resume you will need it now and then.
• Just in case take at least 2 passport photos with you. You can escape it but many times you will need it.
• Carry all your current office documents specially your salary slips and joining letter.

Java Interview Questions

1. What is a transient variable?
A transient variable is a variable that may not be serialized.

2. Which containers use a border Layout as their default layout?
The window, Frame and Dialog classes use a border layout as their default layout.

3. Why do threads block on I/O?
Threads block on I/O (that is enters the waiting state) so that other threads may execute while the I/O Operation is performed.

4. How are Observer and Observable used?
Objects that subclass the Observable class maintain a list of observers. When an Observable object is updated it invokes the update() method of each of its observers to notify the observers that it has changed state. The Observer interface is implemented by objects that observe Observable objects.

5. What is synchronization and why is it important?
With respect to multithreading, synchronization is the capability to control the access of multiple threads to shared resources. Without synchronization, it is possible for one thread to modify a shared object while another thread is in the process of using or updating that object's value. This often leads to significant errors.

6. Can a lock be acquired on a class?
Yes, a lock can be acquired on a class. This lock is acquired on the class's Class object.

7. What's new with the stop(), suspend() and resume() methods in JDK 1.2?
The stop(), suspend() and resume() methods have been deprecated in JDK 1.2.

8. Is null a keyword?
The null value is not a keyword.

9. What is the preferred size of a component?
The preferred size of a component is the minimum component size that will allow the component to display normally.

10. What method is used to specify a container's layout?
The setLayout() method is used to specify a container's layout.

11. Which containers use a FlowLayout as their default layout?
The Panel and Applet classes use the FlowLayout as their default layout.

12. What state does a thread enter when it terminates its processing?
When a thread terminates its processing, it enters the dead state.

13. What is the Collections API?
The Collections API is a set of classes and interfaces that support operations on collections of objects.

14. which characters may be used as the second character of an identifier, but not as the first character of an identifier?
The digits 0 through 9 may not be used as the first character of an identifier but they may be used after the first character of an identifier.

15. What is the List interface?
The List interface provides support for ordered collections of objects.

16. How does Java handle integer overflows and underflows?
It uses those low order bytes of the result that can fit into the size of the type allowed by the operation.

17. What is the Vector class?
The Vector class provides the capability to implement a growable array of objects

18. What modifiers may be used with an inner class that is a member of an outer class?
A (non-local) inner class may be declared as public, protected, private, static, final, or abstract.

19. What is an Iterator interface?
The Iterator interface is used to step through the elements of a Collection.

20. What is the difference between the >> and >>> operators?
The >> operator carries the sign bit when shifting right. The >>> zero-fills bits that have been shifted out.

21. Which method of the Component class is used to set the position and size of a component?
setBounds()

22. How many bits are used to represent Unicode, ASCII, UTF-16, and UTF-8 characters?
Unicode requires 16 bits and ASCII require 7 bits. Although the ASCII character set uses only 7 bits, it is usually represented as 8 bits. UTF-8 represents characters using 8, 16, and 18 bit patterns. UTF-16 uses 16-bit and larger bit patterns.

23 What is the difference between yielding and sleeping?
When a task invokes its yield() method, it returns to the ready state. When a task invokes its sleep() method, it returns to the waiting state.

24. Which java.util classes and interfaces support event handling?
The EventObject class and the EventListener interface support event processing.

25. Is sizeof a keyword?
The sizeof operator is not a keyword.

26. What are wrapper classes?
Wrapper classes are classes that allow primitive types to be accessed as objects.

27. Does garbage collection guarantee that a program will not run out of memory?
Garbage collection does not guarantee that a program will not run out of memory. It is possible for programs to use up memory resources faster than they are garbage collected. It is also possible for programs to create objects that are not subject to garbage collection.

28. What restrictions are placed on the location of a package statement within a source code file?
A package statement must appear as the first line in a source code file (excluding blank lines and comments).

29. Can an object's finalize() method be invoked while it is reachable?
An object's finalize() method cannot be invoked by the garbage collector while the object is still reachable. However, an object's finalize() method may be invoked by other objects.

30. What is the immediate superclass of the Applet class?
Panel

31. What is the difference between preemptive scheduling and time slicing?
Under preemptive scheduling, the highest priority task executes until it enters the waiting or dead states or a higher priority task comes into existence. Under time slicing, a task executes for a predefined slice of time and then reenters the pool of ready tasks. The scheduler then determines which task should execute next, based on priority and other factors.

32. Name three Component subclasses that support painting.
The Canvas, Frame, Panel, and Applet classes support painting.

33. What value does readLine() return when it has reached the end of a file?
The readLine() method returns null when it has reached the end of a file.

34. What is the immediate superclass of the Dialog class?
Window.

35. What is clipping?
Clipping is the process of confining paint operations to a limited area or shape.

36. What is a native method?
A native method is a method that is implemented in a language other than Java.

37. Can a for statement loop indefinitely?
Yes, a for statement can loop indefinitely. For example, consider the following:
for(;;) ;

38. What are order of precedence and associativity, and how are they used?
Order of precedence determines the order in which operators are evaluated in expressions. Associatity determines whether an expression is evaluated left-to-right or right-to-left

39. When a thread blocks on I/O, what state does it enter?
A thread enters the waiting state when it blocks on I/O.

40. To what value is a variable of the String type automatically initialized?
The default value of a String type is null.

41. What is the catch or declare rule for method declarations?
If a checked exception may be thrown within the body of a method, the method must either catch the exception or declare it in its throws clause.

42. What is the difference between a MenuItem and a CheckboxMenuItem?
The CheckboxMenuItem class extends the MenuItem class to support a menu item that may be checked or unchecked.

43. What is a task's priority and how is it used in scheduling?
A task's priority is an integer value that identifies the relative order in which it should be executed with respect to other tasks. The scheduler attempts to schedule higher priority tasks before lower priority tasks.

44. What class is the top of the AWT event hierarchy?
The java.awt.AWTEvent class is the highest-level class in the AWT event-class hierarchy.

45. When a thread is created and started, what is its initial state?
A thread is in the ready state after it has been created and started.

46. Can an anonymous class be declared as implementing an interface and extending a class?
An anonymous class may implement an interface or extend a superclass, but may not be declared to do both.

47. What is the range of the short type?
The range of the short type is -(2^15) to 2^15 - 1.

48. What is the range of the char type?
The range of the char type is 0 to 2^16 - 1.

49. In which package are most of the AWT events that support the event-delegation model defined?
Most of the AWT-related events of the event-delegation model are defined in the java.awt.event package. The AWTEvent class is defined in the java.awt package.

50. What is the immediate superclass of Menu?
MenuItem

51. What is the purpose of finalization?
The purpose of finalization is to give an unreachable object the opportunity to perform any cleanup processing before the object is garbage collected.

52. Which class is the immediate superclass of the MenuComponent class.
Object

53. What invokes a thread's run() method?
After a thread is started, via its start() method or that of the Thread class, the JVM invokes the thread's run() method when the thread is initially executed.

54. What is the difference between the Boolean & operator and the && operator?
If an expression involving the Boolean & operator is evaluated, both operands are evaluated. Then the & operator is applied to the operand. When an expression involving the && operator is evaluated, the first operand is evaluated. If the first operand returns a value of true then the second operand is evaluated. The && operator is then applied to the first and second operands. If the first operand evaluates to false, the evaluation of the second operand is skipped.

55. Name three subclasses of the Component class.
Box.Filler, Button, Canvas, Checkbox, Choice, Container, Label, List, Scrollbar, or TextComponent

56. What is the GregorianCalendar class?
The GregorianCalendar provides support for traditional Western calendars.

57. Which Container method is used to cause a container to be laid out and redisplayed?
validate()

58. What is the purpose of the Runtime class?
The purpose of the Runtime class is to provide access to the Java runtime system.

59. How many times may an object's finalize() method be invoked by the
garbage collector?
An object's finalize() method may only be invoked once by the garbage collector.

60. What is the purpose of the finally clause of a try-catch-finally statement?
The finally clause is used to provide the capability to execute code no matter whether or not an exception is thrown or caught.

61. What is the argument type of a program's main() method?
A program's main() method takes an argument of the String[] type.

62. Which Java operator is right associative?
The = operator is right associative.

63. What is the Locale class?
The Locale class is used to tailor program output to the conventions of a particular geographic, political, or cultural region.64. Can a double value be cast to a byte?
Yes, a double value can be cast to a byte.

65. What is the difference between a break statement and a continue statement?
A break statement results in the termination of the statement to which it applies (switch, for, do, or while). A continue statement is used to end the current loop iteration and return control to the loop statement.

66. What must a class do to implement an interface?
It must provide all of the methods in the interface and identify the interface in its implements clause.

67. What method is invoked to cause an object to begin executing as a separate thread?
The start() method of the Thread class is invoked to cause an object to begin executing as a separate thread.

68. Name two subclasses of the TextComponent class.
TextField and TextArea

69. What is the advantage of the event-delegation model over the earlier event-inheritance model?
The event-delegation model has two advantages over the event-inheritance model. First, it enables event handling to be handled by objects other than the ones that generate the events (or their containers). This allows a clean separation between a component's design and its use. The other advantage of the event-delegation model is that it performs much better in applications where many events are generated. This performance improvement is due to the fact that the event-delegation model does not have to repeatedly process unhandled events, as is the case of the event-inheritance
model.

70. Which containers may have a MenuBar?
Frame

71. How are commas used in the initialization and iteration parts of a for statement?
Commas are used to separate multiple statements within the initialization and iteration parts of a for statement.

72. What is the purpose of the wait(), notify(), and notifyAll() methods?
The wait(),notify(), and notifyAll() methods are used to provide an efficient way for threads to wait for a shared resource. When a thread executes an object's wait() method, it enters the waiting state. It only enters the ready state after another thread invokes the object's notify() or notifyAll() methods.

73. What is an abstract method?
An abstract method is a method whose implementation is deferred to a subclass.

74. How are Java source code files named?
A Java source code file takes the name of a public class or interface that is defined within the file. A source code file may contain at most one public class or interface. If a public class or interface is defined within a source code file, then the source code file must take the name of the public class or interface. If no public class or interface is defined within a source code file, then the file must take on a name that is different than its classes and interfaces. Source code files use the .java extension.

75. What is the relationship between the Canvas class and the Graphics class?
A Canvas object provides access to a Graphics object via its paint() method.

76. What are the high-level thread states?
The high-level thread states are ready, running, waiting, and dead.

77. What value does read() return when it has reached the end of a file?
The read() method returns -1 when it has reached the end of a file.

78. Can a Byte object be cast to a double value?
No, an object cannot be cast to a primitive value.

79. What is the difference between a static and a non-static inner class?
A non-static inner class may have object instances that are associated with instances of the class's outer class. A static inner class does not have any object instances.

80. What is the difference between the String and StringBuffer classes?
String objects are constants. StringBuffer objects are not.

81. If a variable is declared as private, where may the variable be accessed?
A private variable may only be accessed within the class in which it is declared.

82. What is an object's lock and which objects have locks?
An object's lock is a mechanism that is used by multiple threads to obtain synchronized access to the object. A thread may execute a synchronized method of an object only after it has acquired the object's lock. All objects and classes have locks. A class's lock is acquired on the class's Class object.

83. What is the Dictionary class?
The Dictionary class provides the capability to store key-value pairs.

84. How are the elements of a BorderLayout organized?
The elements of a BorderLayout are organized at the borders (North, South, East, and West) and the center of a container.

85. What is the % operator?
It is referred to as the modulo or remainder operator. It returns the remainder of dividing the first operand by the second operand.

86. When can an object reference be cast to an interface reference?
An object reference be cast to an interface reference when the object implements the referenced interface.

87. What is the difference between a Window and a Frame?
The Frame class extends Window to define a main application window that can have a menu bar.

88. Which class is extended by all other classes?
The Object class is extended by all other classes.

89. Can an object be garbage collected while it is still reachable?
A reachable object cannot be garbage collected. Only unreachable objects may be garbage collected..

90. Is the ternary operator written x : y ? z or x ? y : z ?
It is written x ? y : z.

91. What is the difference between the Font and FontMetrics classes?
The FontMetrics class is used to define implementation-specific properties, such as ascent and descent, of a Font object.

92. How is rounding performed under integer division?
The fractional part of the result is truncated. This is known as rounding toward zero.

93. What happens when a thread cannot acquire a lock on an object?
If a thread attempts to execute a synchronized method or synchronized statement and is unable to acquire an object's lock, it enters the waiting state until the lock becomes available.

94. What is the difference between the Reader/Writer class hierarchy and the InputStream/OutputStream class hierarchy?
The Reader/Writer class hierarchy is character-oriented, and the InputStream/OutputStream class hierarchy is byte-oriented.

95. What classes of exceptions may be caught by a catch clause?
A catch clause can catch any exception that may be assigned to the Throwable type. This includes the Error and Exception types.

96. If a class is declared without any access modifiers, where may the class be accessed?
A class that is declared without any access modifiers is said to have package access. This means that the class can only be accessed by other classes and interfaces that are defined within the same package.

97. What is the SimpleTimeZone class?
The SimpleTimeZone class provides support for a Gregorian calendar.

98. What is the Map interface?
The Map interface replaces the JDK 1.1 Dictionary class and is used associate keys with values.99. Does a class inherit the constructors of its superclass?
A class does not inherit constructors from any of its super classes.

100. For which statements does it make sense to use a label?
The only statements for which it makes sense to use a label are those statements that can enclose a break or continue statement.

101. What is the purpose of the System class?
The purpose of the System class is to provide access to system resources.

102. Which TextComponent method is used to set a TextComponent to the read-only state?
setEditable()

103. How are the elements of a CardLayout organized?
The elements of a CardLayout are stacked, one on top of the other, like a deck of cards.

104. Is &&= a valid Java operator?
No, it is not.

105. Name the eight primitive Java types.
The eight primitive types are byte, char, short, int, long, float, double, and boolean.

106. Which class should you use to obtain design information about an object?
The Class class is used to obtain information about an object's design.

107. What is the relationship between clipping and repainting?
When a window is repainted by the AWT painting thread, it sets the clipping regions to the area of the window that requires repainting.

108. Is "abc" a primitive value?
The String literal "abc" is not a primitive value. It is a String object.

109. What is the relationship between an event-listener interface and an event-adapter class?
An event-listener interface defines the methods that must be implemented by an event handler for a particular kind of event. An event adapter provides a default implementation of an event-listener interface.

110. What restrictions are placed on the values of each case of a switch statement?
During compilation, the values of each case of a switch statement must evaluate to a value that can be promoted to an int value.

111. What modifiers may be used with an interface declaration?
An interface may be declared as public or abstract.

112. Is a class a subclass of itself?
A class is a subclass of itself.

113. What is the highest-level event class of the event-delegation model?
The java.util.EventObject class is the highest-level class in the event-delegation class hierarchy.

114. What event results from the clicking of a button?
The ActionEvent event is generated as the result of the clicking of a button.

115. How can a GUI component handle its own events?
A component can handle its own events by implementing the required event-listener interface and adding itself as its own event listener.

116. What is the difference between a while statement and a do statement?
A while statement checks at the beginning of a loop to see whether the next loop iteration should occur. A do statement checks at the end of a loop to see whether the next iteration of a loop should occur. The do statement will always execute the body of a loop at least once.

117. How are the elements of a GridBagLayout organized?
The elements of a GridBagLayout are organized according to a grid. However, the elements are of different sizes and may occupy more than one row or column of the grid. In addition, the rows and columns may have different sizes.

118. What advantage do Java's layout managers provide over traditional windowing systems?
Java uses layout managers to lay out components in a consistent manner across all windowing platforms. Since Java's layout managers aren't tied to absolute sizing and positioning, they are able to accommodate platform-specific differences among windowing systems.

119. What is the Collection interface?
The Collection interface provides support for the implementation of a mathematical bag - an unordered collection of objects that may contain duplicates.

120. What modifiers can be used with a local inner class?
A local inner class may be final or abstract.

121. What is the difference between static and non-static variables?
A static variable is associated with the class as a whole rather than with specific instances of a class. Non-static variables take on unique values with each object instance.

122. What is the difference between the paint() and repaint() methods?
The paint() method supports painting via a Graphics object. The repaint() method is used to cause paint() to be invoked by the AWT painting thread.

123. What is the purpose of the File class?
The File class is used to create objects that provide access to the files and directories of a local file system.

124. Can an exception be rethrown?
Yes, an exception can be rethrown.

125. Which Math method is used to calculate the absolute value of a number?
The abs() method is used to calculate absolute values.

126. How does multithreading take place on a computer with a single CPU?
The operating system's task scheduler allocates execution time to multiple tasks. By quickly switching between executing tasks, it creates the impression that tasks execute sequentially.

127. When does the compiler supply a default constructor for a class?
The compiler supplies a default constructor for a class if no other constructors are provided.

128. When is the finally clause of a try-catch-finally statement executed?
The finally clause of the try-catch-finally statement is always executed unless the thread of execution terminates or an exception occurs within the execution of the finally clause.

129. Which class is the immediate superclass of the Container class?
Component

130. If a method is declared as protected, where may the method be accessed?
A protected method may only be accessed by classes or interfaces of the same package or by subclasses of the class in which it is declared.

131. How can the Checkbox class be used to create a radio button?
By associating Checkbox objects with a CheckboxGroup.

132. Which non-Unicode letter characters may be used as the first character of an identifier?
The non-Unicode letter characters $ and _ may appear as the first character of an identifier

133. What restrictions are placed on method overloading?
Two methods may not have the same name and argument list but different return types.

134. What happens when you invoke a thread's interrupt method while it is sleeping or waiting?
When a task's interrupt() method is executed, the task enters the ready state. The next time the task enters the running state, an InterruptedException is thrown.

135. What is casting?
There are two types of casting, casting between primitive numeric types and casting between object references. Casting between numeric types is used to convert larger values, such as double values, to smaller values, such as byte values. Casting between object references is used to refer to an object by a compatible class, interface, or array type reference.

136. What is the return type of a program's main() method?
A program's main() method has a void return type.

137. Name four Container classes.
Window, Frame, Dialog, FileDialog, Panel, Applet, or ScrollPane

138. What is the difference between a Choice and a List?
A Choice is displayed in a compact form that requires you to pull it down to see the list of available choices. Only one item may be selected from a Choice. A List may be displayed in such a way that several List items are visible. A List supports the selection of one or more List items.

139. What class of exceptions are generated by the Java run-time system?
The Java runtime system generates RuntimeException and Error exceptions.

140. What class allows you to read objects directly from a stream?
The ObjectInputStream class supports the reading of objects from input streams.

141. What is the difference between a field variable and a local variable?
A field variable is a variable that is declared as a member of a class. A local variable is a variable that is declared local to a method.

142. Under what conditions is an object's finalize() method invoked by the garbage collector?
The garbage collector invokes an object's finalize() method when it detects that the object has become unreachable.

143. How are this () and super () used with constructors?
this() is used to invoke a constructor of the same class. super() is used to invoke a superclass constructor.

144. What is the relationship between a method's throws clause and the exceptions that can be thrown during the method's execution?
A method's throws clause must declare any checked exceptions that are not caught within the body of the method.

145. What is the difference between the JDK 1.02 event model and the event-delegation model introduced with JDK 1.1?
The JDK 1.02 event model uses an event inheritance or bubbling approach. In this model, components are required to handle their own events. If they do not handle a particular event, the event is inherited by (or bubbled up to) the component's container. The container then either handles the event or it is bubbled up to its container and so on, until the highest-level container has been tried.
In the event-delegation model, specific objects are designated as event handlers for GUI components. These objects implement event-listener interfaces. The event-delegation model is more efficient than the event-inheritance model because it eliminates the processing required to support the bubbling of unhandled events.

146. How is it possible for two String objects with identical values not to be equal under the == operator?
The == operator compares two objects to determine if they are the same object in memory. It is possible for two String objects to have the same value, but located indifferent areas of memory.

147. Why are the methods of the Math class static?
So they can be invoked as if they are a mathematical code library.

148. What Checkbox method allows you to tell if a Checkbox is checked?
getState()

149. What state is a thread in when it is executing?
An executing thread is in the running state.

150. What are the legal operands of the instanceof operator?
The left operand is an object reference or null value and the right operand is a class, interface, or array type.

151. How are the elements of a GridLayout organized?
The elements of a GridBad layout are of equal size and are laid out using the squares of a grid.

152. What an I/O filter?
An I/O filter is an object that reads from one stream and writes to another, usually altering the data in some way as it is passed from one stream to another.

153. If an object is garbage collected, can it become reachable again?
Once an object is garbage collected, it ceases to exist. It can no longer become reachable again.

154. What is the Set interface?
The Set interface provides methods for accessing the elements of a finite mathematical set. Sets do not allow duplicate elements.

155. What classes of exceptions may be thrown by a throw statement?
A throw statement may throw any expression that may be assigned to the Throwable type.

156. What are E and PI?
E is the base of the natural logarithm and PI is mathematical value pi.

157. Are true and false keywords?
The values true and false are not keywords.

158. What is a void return type?
A void return type indicates that a method does not return a value.

159. What is the purpose of the enableEvents() method?
The enableEvents() method is used to enable an event for a particular object. Normally, an event is enabled when a listener is added to an object for a particular event. The enableEvents() method is used by objects that handle events by overriding their event-dispatch methods.

160. What is the difference between the File and RandomAccessFile classes?
The File class encapsulates the files and directories of the local file system. The RandomAccessFile class provides the methods needed to directly access data contained in any part of a file.

161. What happens when you add a double value to a String?
The result is a String object.162. What is your platform's default character encoding?
If you are running Java on English Windows platforms, it is probably Cp1252. If you are running Java on English Solaris platforms, it is most likely 8859_1..

163. Which package is always imported by default?
The java.lang package is always imported by default.

164. What interface must an object implement before it can be written to a stream as an object?
An object must implement the Serializable or Externalizable interface before it can be written to a stream as an object.

165. How are this and super used?
this is used to refer to the current object instance. super is used to refer to the variables and methods of the superclass of the current object instance.

166. What is the purpose of garbage collection?
The purpose of garbage collection is to identify and discard objects that are no longer needed by a program so that their resources may be reclaimed and
reused.

167. What is a compilation unit?
A compilation unit is a Java source code file.

168. What interface is extended by AWT event listeners?
All AWT event listeners extend the java.util.EventListener interface.

169. What restrictions are placed on method overriding?
Overridden methods must have the same name, argument list, and return type.
The overriding method may not limit the access of the method it overrides.
The overriding method may not throw any exceptions that may not be thrown
by the overridden method.

170. How can a dead thread be restarted?
A dead thread cannot be restarted.

171. What happens if an exception is not caught?
An uncaught exception results in the uncaughtException() method of the thread's ThreadGroup being invoked, which eventually results in the termination of the program in which it is thrown.

172. What is a layout manager?
A layout manager is an object that is used to organize components in a container.

173. Which arithmetic operations can result in the throwing of an ArithmeticException?
Integer / and % can result in the throwing of an ArithmeticException.

174. What are three ways in which a thread can enter the waiting state?
A thread can enter the waiting state by invoking its sleep() method, by blocking on I/O, by unsuccessfully attempting to acquire an object's lock, or by invoking an object's wait() method. It can also enter the waiting state by invoking its
(deprecated) suspend() method.

175. Can an abstract class be final?
An abstract class may not be declared as final.176. What is the ResourceBundle class?
The ResourceBundle class is used to store locale-specific resources that can be loaded by a program to tailor the program's appearance to the particular locale in which it is being run.

177. What happens if a try-catch-finally statement does not have a catch clause to handle an exception that is thrown within the body of the try statement?
The exception propagates up to the next higher level try-catch statement (if any) or results in the program's termination.

178. What is numeric promotion?
Numeric promotion is the conversion of a smaller numeric type to a larger numeric type, so that integer and floating-point operations may take place. In numerical promotion, byte, char, and short values are converted to int
values. The int values are also converted to long values, if necessary. The long and float values are converted to double values, as required.

179. What is the difference between a Scrollbar and a ScrollPane?
A Scrollbar is a Component, but not a Container. A ScrollPane is a Container. A ScrollPane handles its own events and performs its own scrolling.

180. What is the difference between a public and a non-public class?
A public class may be accessed outside of its package. A non-public class may not be accessed outside of its package.

181. To what value is a variable of the boolean type automatically initialized?
The default value of the boolean type is false.

182. Can try statements be nested?
Try statements may be tested.

183. What is the difference between the prefix and postfix forms of the ++ operator?
The prefix form performs the increment operation and returns the value of the increment operation. The postfix form returns the current value all of the expression and then performs the increment operation on that value.

184. What is the purpose of a statement block?
A statement block is used to organize a sequence of statements as a single statement group.

185. What is a Java package and how is it used?
A Java package is a naming context for classes and interfaces. A package is used to create a separate name space for groups of classes and interfaces. Packages are also used to organize related classes and interfaces into a single API unit and to control accessibility to these classes and interfaces.

186. What modifiers may be used with a top-level class?
A top-level class may be public, abstract, or final.

187. What are the Object and Class classes used for?
The Object class is the highest-level class in the Java class hierarchy. The Class class is used to represent the classes and interfaces that are loaded by a Java program.

188. How does a try statement determine which catch clause should be used to handle an exception?
When an exception is thrown within the body of a try statement, the catch clauses of the try statement are examined in the order in which they appear. The first catch clause that is capable of handling the exception is executed.
The remaining catch clauses are ignored.

189. Can an unreachable object become reachable again?
An unreachable object may become reachable again. This can happen when the object's finalize() method is invoked and the object performs an operation which causes it to become accessible to reachable objects.

190. When is an object subject to garbage collection?
An object is subject to garbage collection when it becomes unreachable to the program in which it is used.

191. What method must be implemented by all threads?
All tasks must implement the run() method, whether they are a subclass of Thread or implement the Runnable interface.

192. What methods are used to get and set the text label displayed by a Button object?
getLabel() and setLabel()

193. Which Component subclass is used for drawing and painting?
Canvas

194. What are synchronized methods and synchronized statements?
Synchronized methods are methods that are used to control access to an object. A thread only executes a synchronized method after it has acquired the lock for the method's object or class. Synchronized statements are similar to synchronized methods. A synchronized statement can only be executed after a thread has acquired the lock for the object or class referenced in the synchronized statement

195. What are the two basic ways in which classes that can be run as threads may be defined?
A thread class may be declared as a subclass of Thread, or it may implement the Runnable interface.

196. What are the problems faced by Java programmers who don't use layout managers?
Without layout managers, Java programmers are faced with determining how their GUI will be displayed across multiple windowing systems and finding a common sizing and positioning that will work within the constraints imposed by each windowing system.

197. What is the difference between an if statement and a switch statement?
The if statement is used to select among two alternatives. It uses a boolean expression to decide which alternative should be executed. The switch statement is used to select among multiple alternatives. It uses an int expression to determine which alternative should be executed.

Java Interview Questions

Q1. How could Java classes direct program messages to the system console, but error messages, say to a file?

A. The class System has a variable out that represents the standard output, and the variable err that represents the standard error device. By default, they both point at the system console. This how the standard output and error could be re-directed:

PrintStream st = new PrintStream(new FileOutputStream("output.txt")); System.setErr(st); System.setOut(st);

Q2. What's the difference between an interface and an abstract class?

A. An abstract class may contain code in method bodies, which is not allowed in an interface. Java does not allow inheritance from multiple classes. On the other hand, you can implement multiple interfaces in your class. Also, an abstract class can contain private and protected members, and non-static member variables.

Q3. Why would you use a synchronized block vs. synchronized method?

A. Synchronized blocks place locks for shorter periods than synchronized methods, increasing the possibility of concurrent access to the protected code.

Q4. Explain the usage of the keyword transient?

A. This keyword indicates that the value of this member variable is not serialized with the object. When the class will be de-serialized, this variable will be initialized with a default value of its data type (e.g. zero for integers).

Q5. How can you force garbage collection?

A. You can't force GC, but could request it by calling System.gc(). JVM does not guarantee that GC will be started immediately, if at all.

Q6. How do you know if an explicit object casting is needed?

A. You can use an object anywhere it's declared class or a super-class is expected. You have to cast if a sub-class is expected, e.g. if you want to assign to a sub-class object or to use a sub-class's method.

Q7. What's the difference between the methods sleep() and wait()

A. The code sleep(1000) suspends the thread for at least one second. The code wait(1000), causes a wait of at most one second. A thread could stop waiting earlier if it receives the notify() or notifyAll() call. The method wait() is defined in the class Object and the method sleep() is defined in the class Thread.

Q8. Can you write a Java class that could be used both as an applet as well as an application?

A. Yes. Add a main() method to the applet's class.

Q9. What's the difference between constructors and other methods?

A. Constructors must have the same name as the class and can not return a value. They are only called once for a given object while regular methods could be called many times.

Q10. Can you call one constructor from another if a class has multiple constructors

A. Yes. Use this() syntax, passing any required parameters.

Q11. Explain the usage of Java packages.

A. This is a way to organize files when a project consists of multiple modules. It also helps resolve naming conflicts when different packages have classes with the same names. Package-private access level also allows you to protect data from being used by the non-authorized classes.

Q12. If a class is located in a package, what do you need to change in the OS environment to be able to use it?

A. You need to add a directory or a jar file that contains the package directories to the CLASSPATH environment variable. Let's say a class Employee belongs to a package com.xyz.hr; and is located in the file c:\dev\com\xyz\hr\Employee.java. In this case, you'd need to add c:\dev to the variable CLASSPATH. If this class contains the method main(), you could test it from a command prompt window as follows:

c:\>java com.xyz.hr.Employee

Alternatively you can pass the classpath as a parameter to the JRE, e.g. java -cp "the-classpath"

Q13. What's the difference between J2SDK 1.5 and J2SDK 5.0?

A.There's no difference, Sun Microsystems just re-branded this version.

Q14. What would you use to compare two String variables - the operator == or the method equals()?

A. I'd use the method equals() to compare the values of the Strings and the == to check if two variables point at the same instance of a String object.

Q15. Does it matter in what order catch statements for FileNotFoundException and IOExceptipon are written?

A. Yes, it does. The FileNoFoundException is inherited from the IOException. Exception's subclasses should be caught first, otherwise the super-class catch will hide the sub-class.

Q16. Can an inner class declared inside of a method access local variables of this method?

A. It's possible if these variables are final.

Q17. What can go wrong if you replace && with & in the following code:

String a=null; if (a!=null && a.length()>10) {...}

A. A single ampersand here would lead to a NullPointerException.

Q18. What's the main difference between a Vector and an ArrayList

A. Java Vector class is internally synchronized and ArrayList is not.

Q19. When should the method invokeLater()be used?

A. This method is used to ensure that the Runnable passed to invokeLater() is executed on the event-dispatching thread.

Q20. How can a subclass call a method or a constructor defined in a superclass?

A. Use the following syntax: super.myMethod(); To call a constructor of the superclass, just call super() in the first line of the subclass's constructor, passing any required parameters.

For senior-level developers:

Q21. What's the difference between a queue and a stack?

A. Stacks works by last-in-first-out rule (LIFO), while queues use the FIFO (first-in, first-out) rule.

Q22. You can create an abstract class that contains only abstract methods. On the other hand, you can create an interface that declares the same methods. So can you use abstract classes instead of interfaces?

A. Yes, but abstract classes are more limited because a class can only extend one class but can implement multiple interfaces.

Q23. What comes to mind when you hear about a young generation in Java?

A. Garbage collection; a young generation is a recent collection of newly created objects, which is reclaimed more aggressively than older ones.

Q24. What comes to mind when someone mentions a shallow copy in Java?

A. Object cloning; a shallow copy reuses references to the original's member variables, but a (complete) deep copy clones the entire object tree.

Q25. If you're overriding the method equals() of an object, which other method you might also consider?

A. hashCode(), because the hash algorithm should use the same member variables as equals().

Q26. You are planning to do an indexed search in a list of objects. Which of the two Java collections should you use:
ArrayList or LinkedList?

A. ArrayList

Q27. How would you make a copy of an entire Java object with its state?

A. Have this class implement Cloneable interface and call its method clone().

Q28. How can you minimize the need of garbage collection and make the memory use more effective?

A. Use object pooling to avoid creating new objects and weak object references to avoid keeping objects in memory that you can cheaply reconstruct.

Q29. There are two classes: A and B. The class B needs to inform a class A when some important event has happened. What Java technique would you use to implement it?

A. If these classes are threads I'd consider notify() or notifyAll(). For regular classes you can use the Observer interface. or some other implementation of the Listener pattern.

Q30. What access level do you need to specify in the class declaration to ensure that only classes from the same directory can access it?

A. You do not need to specify any access level, and Java will use a default package-private access level.

Java Interview Questions

1: OOPS and CORE JAVA
· What is JVM (Java Virtual Machine)?
· What is JIT (Just- in-Time) Compilation?
· What is Object Oriented Programming?
· What’s a Class?
· What’s an Object?
· What’s the relation between Classes and Objects?
· What are different properties provided by Object-oriented systems?
· How do you implement inheritance in Java?
· How can we implement polymorphism in Java?
· What is an Abstract class?
· What are Abstract methods?
· What’s the difference between “Abstract” classes and “Interfaces”?
· What’s difference between Static and Non-Static fields of a class?
· What are inner classes and what’s the practical implementation of inner classes?
· What are packages?
· What is a constructor in class?
· Can constructors be parameterized?
· What is the use if “instance of” keyword?
· What are Native methods in Java?
· How do refer to a current instance of object?
· Explain in depth Garbage collector?
· How does the garbage collector determine that the object has to be marked for
deletion?
· Can you explain “finalize ()” method?
· How can we force the garbage collector to run?
· What’s the main difference between “Switch” and “If” comparison?
· What’s the use of JAVAP tool?
· What are applets?
· In which package is, the applet class located?
· What are native interfaces in Java?
· What are Class loaders?
· What is Bootstrap, Extension and System Class loader?
· Can you explain the flow between bootstrap, extension and system class loader?
· Can you explain how can you practically do dynamic loading?
· What is Reflection API in Java?
· What’s the difference between static and dynamic class loading?
· How can you copy one array in to a different array?
· Can you explain the core collection interfaces?
· Can you explain in brief the collection classes which implement the collection
interfaces?
· What’s the difference between standard JAVA array and Array List class?
· What’s the use of “ensure Capacity” in Array List class?
· How can we obtain an array from an Array List class?
· What is “Linked List” class for?
· Can you explain Hash Set class in collections?
· What is Linked Hash Set class?
· What is a Tree Set class?
· What’s the use of Comparator Interface?
· How can we access elements of a collection?
· What is Map and SortedMap Interface?
· Have you used any collection algorithm?
· Why do we use collections when we had traditional ways for collection?
· Can you name the legacy classes and interface for collections?
· What is Enumeration Interface?
· What’s the main difference between Array List / Hash Map and Vector / Hash
table?
· Are String object Immutable, Can you explain the concept?
· What is a String Buffer class and how does it differs from String class?
· What is the difference between String Builder and String Buffer class?
· What is Pass by Value and Pass by reference? How does JAVA handle the same?
· What are access modifiers?
· What is Assertion?
· Can you explain the fundamentals of deep and shallow Cloning?
· How do we implement shallow cloning?
· How do we implement deep cloning?
· What’s the impact of private constructor?
· What are the situations you will need a constructor to be private?
· Can you explain final modifier?
· What are static Initializes?
· If we have multiple static initialize blocks how are the sequence handled?
· Define casting? What are the different types of Casting?
· Can you explain Widening conversion and Narrowing conversion?
· Can we assign parent object to child objects?
· Define exceptions?
· Can you explain in short how JAVA exception handling works?
· Can you explain different exception types?
· Can you explain checked and unchecked exceptions?
· Can we create our own exception class?
· What are chained exceptions?
· What is serialization?
· How do we implement serialization actually?
· What’s the use of Externalizable Interface?
· What is JAVA doc utility?
2: Threading
· What’s difference between thread and process?
· What is thread safety and synchronization?
· What is semaphore?
· What are monitors?
· What’s the importance of synchronized blocks?
· How do we create threads?
· What’s the difference in using run able and extends in threads?
· Can you explain Thread. Sleep?
· How to stop a thread?
· What is wait () and notify ()?
· Can you explain how Scheduling and Priority works in threads?
· Can you explain Yielding in threading?
· What are daemon threads?
· How do we implement single threaded model in servlets?
3: JDBC
· How does JAVA interact with databases?
· Can we interact with non-relational sources using JDBC?
· Can you explain in depth the different sections in JDBC?
· Can you explain in short how you go about using JDBC API in code?
· How do you handle SQL exceptions?
Twist: - (A) Can you explain “SQL Exception” class in detail?
Twist: - (A) what is SQL State in SQL Exceptions?
· If there is more than one exception in SQL Exception” class how to go about
displaying it?
· Explain Type1, Type2, Type3, and Type4 drivers in JDBC?
· What are the advantages and disadvantages of using JDBC-ODBC bridge driver?
· What are the advantages and disadvantages of using Native-API/ Partially Java
Driver?
· What are the advantages and disadvantages of using Net-Protocol/ All-Java
driver?
· What are the advantages and disadvantages of using Native-protocol/ All-Java
driver?
· Advantages of using JDBC-ODBC bridge driver:-
· Disadvantages of using JDBC-ODBC bridge driver:-
· Advantages of using Native-API/ Partially Java Driver:-
· Dis-advantages of using Native-API/ Partially Java Driver:-
· Advantages of using Net-Protocol/ All-Java driver:-
· Disadvantages of using Net-Protocol/ All- Java driver:-
· Advantages of using Native-protocol/ All-Java driver:-
· Disadvantages of using Native-protocol/ All-Java driver:-
· Define meta-data?
· What is Database Metadata?
· Can you explain “Connection Factory” class?
· I want to display tables of a database how do I do it?
· Define “Result Set Meta Data”?
· What is the difference between “Result Set” and “Row Set”?
· Can “Result Set” objects be serialized?
· Explain “Result Set”, “Row Set”, “Cached Row set”, “JdbcRowset” and “Web
Row Set”?
· What are the different types of result set?
· Explain the concept of “Prepared Statement “statement interface?
· What’s the difference between “Statement” and “Prepared Statement”?
· How can we call stored procedure using JDBC?
· Can you explain “Callable Statement” interface in detail?
· How do you get a result set object from stored procedure?
· (A) How can we do batch updates using “Callable Statement” Interface?
· Define transactions?
· What is ACID in transaction?
· What are the four essential properties of a transaction?
· Explain concurrency and locking?
· What are different types of locks?
· What are the different types of levels of resource on which locks can be placed?
· Define lock escalation?
· What is Table level and Row level locking?
· What are the problems that can occur if you do not implement locking properly?
· What are different transaction levels?
· Twist: - what are different types of locks?
· What is difference between optimistic and pessimistic locking?
· What are deadlocks?
· How can we set transaction level through JDBC API?
· Can you explain transaction control in JDBC?
· What are Save points in a transaction?
4: Servlets and JSP
· What are Servlets?
· What are advantages of servlets over CGI?
· Can you explain Servlet life cycle?
· What are the two important API’s in for Servlets?
· Can you explain in detail “javax.servlet” package?
· What’s the use of Servlet Context?
· How do we define an application level scope for servlet?
· What's the difference between Generic Servlet and Http Servlet?
· Can you explain in detail javax.servlet.http package?
· What’s the architecture of a Servlet package?
· Why is HTTP protocol called as a stateless protocol?
· What are the different ways we can maintain state between requests?
· What is URL rewriting?
· What are cookies?
· What are sessions in Servlets?
· What the difference is between get Session (true) and get Session (false)?
· What’s the difference between “do Post” and “do get” methods?
· Which are the different ways you can communicate between servlets?
· What is functionality of “Request Dispatcher” object?
· How do we share data using “get Servlet Context ()”?
· Explain the concept of SSI?
· What are filters in JAVA?
· Can you explain in short how do you go about implementing filters using Apache
Tomcat?
· Twist: - Explain step by step of how to implement filters?
· What’s the difference between Authentication and authorization?
· Explain in brief the directory structure of a web application?
· Can you explain JSP page life cycle?
· What is EL?
· How does EL search for an attribute?
· What are the implicit EL objects in JSP?
· How can we disable EL?
· What is JSTL?
· Can you explain in short what the different types of JSTL tags are?
· (I) How can we use beans in JSP?
· What is the use of ?
· What is tag for?
· What are JSP directives?
· What are Page directives?
· What are including directives?
· Can you explain taglib directives?
· How does JSP engines instantiate tag handler classes’ instances?
· What’s the difference between JavaBeans and taglib directives?
· What are the different scopes an object can have in a JSP page?
· What are different implicit objects of JSP?
· What are different Authentication Options available in servlets?
· Can you explain how do we practically implement security on a resource?
· How do we practically implement form based authentication?
· How do we authenticate using JDBC?
· Can you explain JDBCRealm?
· Can you explain how do you configure JNDIRealm?
· How did you implement caching in JSP?
· What is the difference between Servletcontext and ServletConfig?
· How do we prevent browser from caching output of my JSP pages?
· Can we explicitly destroy a servlet object?
5: EJB
· What is EJB?
· What are the different kind of Ebb’s?
· You are designing architecture for a project how do you decide whether you
should use session, entity or message driven bean?
· Can you explain “EJBHome” and “EJBObject” in EJB?
· Can client directly create object of session or entity beans?
· Can you explain the concept of local interfaces?
· What are the limitations of using Local object?
· Which application server have you used for EJB?
· Can you explain step by step practically developing and deploying EJB
component?
· What is Passivation and Activation in EJB?
· Can beans who are involved in transaction have “Passivation” process?
· How does the server decide which beans to passivity and activate?
· In what format is the conversational data written to the disk?
· Can you explain in brief Life cycle for Stateless and Stateful beans?
6: Struts
· (I)What’s MVC pattern?
· (B) Define struts?
· (A) Can you explain the directory structure for a struts folder in brief?
· (I) Can you give an overview of how a struts application flows?
· Twist: - What are action and action form classes in Struts?
7: XML and Web Services
· What is XML?
· What is the version information in XML?
· What is ROOT element in XML?
· If XML does not have closing tag will it work?
· Is XML case sensitive?
· What is the difference between XML and HTML?
· Is XML meant to replace HTML?
· Can you explain why your project needed XML?
· What is DTD (Document Type definition)?
· What is well formed XML?
· What is a valid XML?
· What is CDATA section in XML?
· What is CSS?
· What is XSL?
· What is element and attributes in XML?
· What are the standard ways of parsing XML document?
· In What scenarios will you use a DOM parser and SAX parser?
· What is XSLT?
· Define XPATH?
· What is the concept of XPOINTER?
· What is a Web Service?
· What is DISCO?
· What is SOAP?
· What is WSDL?
· Can you explain UDDI?
· Can you explain JAXP?
· What is a XML registry?
· What is JAXR?
· What is JAXM?
· Can you explain JAX-RPC?
· How do you practically implement Web Services?
· How do we consume a web service?
· Are web services Stateful?
8: Internationalization
· Can you explain i18n and l10n?
· Can you explain internationalization and localization?
· What is Locale?
· How do we display numbers, currency and Dates according to proper Locale
format?
· what are resource bundles?
· How do we load a resource bundle file?
· How can we do inheritance in resource bundles?
9: JNI
· What is Native Interface in JAVA?
· Can you say in brief steps required to implement Native interfaces in Java?
· Can JNI be used for VB6, C# or VB.NET directly?
· What are JNI functions and pointers?
· How does the garbage collector know JNI objects are no more used?
· Twist: - What are the different types of references JNI supports?
· Twist: - How to do you delete global objects?
· How does the native language C or C++ understand data types in JAVA?
· Can you explain exception handling in JNI?
· What are limitations for “JNIEnv” pointer in multi- threading scenarios?
· What are the advantages and disadvantages of using “JNI”?
10: Architecture
· What are design patterns?
· Can you list down all patterns and their classification?
· What is the difference between Factory and Abstract Factory Patterns?
· What is MVC pattern?
· How can we implement singleton pattern in JAVA?
· How do you implement prototype pattern in JAVA?
· Can you give a practical implementation of FAÇADE patterns?
· How can we implement observer pattern in JAVA?
· What is three tier architecture?
· What is Service Oriented architecture?
· What is aspect oriented programming?
· How can you implement AOP practically in JAVA?
· What is Inversion of control?
· What is OR mapping?
11: UML
· What is UML?
· How many types of diagrams are there in UML?
· What are advantages of using UML?
· What is the sequence of UML diagrams in project?
· Give a small brief explanation of all Elements in activity diagrams?
· Explain Different elements of a collaboration diagram?
· Explain Component diagrams?
· Describe the various components in sequence diagrams?
· What are the elements in State Chart diagrams?
· Describe different elements in Static Chart diagrams?
· Explain the different elements of a Use Case?
12: Project Management
· What is project management?
· Is spending in IT projects constant through out the project?
· Who is a stakeholder?
· Can you explain project life cycle?
· Are risk constant through out the project?
· Can you explain different software development life cycles?
· What is triple constraint triangle in project management?
· What is a project baseline?
· What is effort variance?
· How is normally a project management plan document organized?
· (I)How do you estimate a project?
· What is CAR (Causal Analysis and Resolution)?
· What is DAR (Decision Analysis and Resolution)?
· What is a fish bone diagram?
· What is pare to principle?
· How do you handle change request?
· What is internal change request?
· What is difference between SITP and UTP in testing?
· What is the software you have used for project management?
· What are the metrics followed in project management?
· You have people in your team who do not meet there deadlines or do not perform
what are the actions you will take?
· What is black box testing and White box testing?
· What’s the difference between Unit testing, Assembly testing and Regression
testing?
· What is V model in testing?
· How do you start a project?
· How did you do resource allocations?
· How will you do code reviews?
· What is CMMI?
· What are the five levels in CMMI?
· What is continuous and staged representation?
· Can you explain the process areas?
· What is SIX sigma?
· What is DMAIC and DMADV?
· What are the various roles in Six Sigma implementation?
· What are function points?
· What are the different types of elementary process in FPA?
· What are the different elements in Functions points?
· Can you explain in GSC and VAF in function points?
· What are unadjusted function points and how is it calculated?
· Can you explain steps in function points?
· What is the FP per day in your current company?
· Do you know Use Case points?
· What is COCOMO I, COCOMOII and COCOMOIII?
· What is SMC approach of estimation?
· How do you estimate maintenance project and change requests?
13: Database
· What is database or database management systems (DBMS)?
· What is SQL?
· What’s difference between DBMS and RDBMS?
· What are CODD rules?
· What are E-R diagrams?
· How many types of relationship exist in database designing? What is
normalization? What are different type of normalization?
· What is denormalization?
· Can you explain Fourth Normal Form?
· Can you explain Fifth Normal Form?
· What’s the difference between Fourth and Fifth normal form?
· Have you heard about sixth normal form?
· What are DML and DDL statements?
· How do we select distinct values from a table?
· What is like operator for and what are wild cards?
· Can you explain Insert, Update and Delete query?
· What is order by clause?
· What is the SQL In clause?
· Can you explain the between clause?
· I have an employee salary table how do we find the second highest from it?
· What are different types of joins in SQL?
· What is “CROSS JOIN”?
· You want to select the first record in a given set of rows?
· What is the default “SORT” order for a SQL?
· What is a self-join?
· What’s the difference between DELETE and TRUNCATE?
· .What are Wildcard operators?
· Twist: - What is like clause in SQL?
· What’s the difference between “UNION” and “UNION ALL”?
· What are cursors and what are the situations you will use them?
· What are the steps to create a cursor?
· What is “Group by” clause?
· What is the difference between “HAVING” and “WHERE” clause?
· What is a Sub-Query?
· What are Aggregate and Scalar Functions?
· Can you explain the SELECT INTO Statement?
· What is a View?
· What is “Correlated Sub queries”?
· What is SQl injection?
· What is “Data Warehousing”?
· What are Data Marts?
· What are Fact tables and Dimension Tables?
· Twist: - What is Dimensional Modeling?
· Twist: - What is Star Schema Design?
· What is Snow Flake Schema design in database?
· Twist: - What’s the difference between Star and Snow flake schema?
· What is ETL process in Data warehousing?
· Twist: - What are the different stages in “Data warehousing”?
· What is “Data mining”?
· Compare “Data mining” and “Data Warehousing”?
· What are indexes?
· What are B-Trees?
· I have a table which has lot of inserts, is it a good database design to create
indexes on that table?
· Twist: - Insert’s are slower on tables which have indexes, justify it?
· Twist: - Why do page splitting happen?
· What are “Table Scan’s” and “Index Scan’s”?
· What are the two types of indexes and explain them in detail?
· Twist: - What’s the difference between clustered and non-clustered indexes?

Java Interview Questions

Question: What if the main method is declared as private?

Question: What if the static modifier is removed from the signature of the main method?

Question: What if I write static public void instead of public static void?

Q:Question: What if I do not provide the String array as the argument to the method?

Question: What is the first argument of the String array in main method?

Question: If I do not provide any arguments on the command line, then the String array of Main method will be empty of null?

Question: How can one prove that the array is not null but empty?

Question: What environment variables do I need to set on my machine in order to be able to run Java programs?

Question: Can an application have multiple classes having main method?

Question: Can I have multiple main methods in the same class?

Question: Do I need to import java.lang package any time? Why ?

Question: Can I import same package/class twice? Will the JVM load the package twice at runtime?

Question: What are Checked and UnChecked Exception?

Question: What is Overriding?

Question: What are different types of inner classes?


Q: What if the main method is declared as private?
A: The program compiles properly but at runtime it will give "Main method not public." message.




Q: What if the static modifier is removed from the signature of the main method?
A: Program compiles. But at runtime throws an error "NoSuchMethodError".




Q: What if I write static public void instead of public static void?
A: Program compiles and runs properly.




Q: What if I do not provide the String array as the argument to the method?
A: Program compiles but throws a runtime error "NoSuchMethodError".




Q: What is the first argument of the String array in main method?
A: The String array is empty. It does not have any element. This is unlike C/C++ where the first element by default is the program name.




Q: If I do not provide any arguments on the command line, then the String array of Main method will be empty of null?
A: It is empty. But not null.




Q: How can one prove that the array is not null but empty?
A: Print args.length. It will print 0. That means it is empty. But if it would have been null then it would have thrown a NullPointerException on attempting to print args.length.




Q: What environment variables do I need to set on my machine in order to be able to run Java programs?
A: CLASSPATH and PATH are the two variables.




Q: Can an application have multiple classes having main method?
A: Yes it is possible. While starting the application we mention the class name to be run. The JVM will look for the Main method only in the class whose name you have mentioned. Hence there is not conflict amongst the multiple classes having main method.




Q: Can I have multiple main methods in the same class?
A: No the program fails to compile. The compiler says that the main method is already defined in the class.




Q: Do I need to import java.lang package any time? Why ?
A: No. It is by default loaded internally by the JVM.




Q: Can I import same package/class twice? Will the JVM load the package twice at runtime?
A: One can import the same package or same class multiple times. Neither compiler nor JVM complains abt it. And the JVM will internally load the class only once no matter how many times you import the same class.




Q: What are Checked and UnChecked Exception?
A: A checked exception is some subclass of Exception (or Exception itself), excluding class RuntimeException and its subclasses.
Making an exception checked forces client programmers to deal with the possibility that the exception will be thrown. eg, IOException thrown by java.io.FileInputStream's read() method•
Unchecked exceptions are RuntimeException and any of its subclasses. Class Error and its subclasses also are unchecked. With an unchecked exception, however, the compiler doesn't force client programmers either to catch the
exception or declare it in a throws clause. In fact, client programmers may not even know that the exception could be thrown. eg, StringIndexOutOfBoundsException thrown by String's charAt() method• Checked exceptions must be caught at compile time. Runtime exceptions do not need to be. Errors often cannot be.



Q: What is Overriding?
A: When a class defines a method using the same name, return type, and arguments as a method in its superclass, the method in the class overrides the method in the superclass.
When the method is invoked for an object of the class, it is the new definition of the method that is called, and not the method definition from superclass. Methods may be overridden to be more public, not more private.



Q: What are different types of inner classes?
A: Nested -level classes, Member classes, Local classes, Anonymous classes
Nested -level classes- If you declare a class within a class and specify the static modifier, the compiler treats the class just like any other -level class.
Any class outside the declaring class accesses the nested class with the declaring class name acting similarly to a package. eg, outer.inner. -level inner classes implicitly have access only to static variables.There can also be inner interfaces. All of these are of the nested -level variety.

Member classes - Member inner classes are just like other member methods and member variables and access to the member class is restricted, just like methods and variables. This means a public member class acts similarly to a nested -level class. The primary difference between member classes and nested -level classes is that member classes have access to the specific instance of the enclosing class.

Local classes - Local classes are like local variables, specific to a block of code. Their visibility is only within the block of their declaration. In order for the class to be useful beyond the declaration block, it would need to implement a
more publicly available interface.Because local classes are not members, the modifiers public, protected, private, and static are not usable.

Anonymous classes - Anonymous inner classes extend local inner classes one level further. As anonymous classes have no name, you cannot provide a constructor.