Java Interview Questions - J2EE JSP interview question

1. Hibernate Interview Questions
2. Are the imports checked for validity at compile time? e.g. will the code containing an import such as java.lang.ABCD compile?
3. c1 = new MyClass ();
4. c3 = new MyClass ();
5. Can a .java file contain more than one java classes?
6. Can a public class MyClass be defined in a source file named YourClass.java?
7. Can a top level class be private or protected?
8. Can an application have multiple classes having main method?
9. Can an unreachable object become reachable again?
10. Can applets communicate with each other?
11. Can I have multiple main methods in the same class?
12. Can I import same package/class twice? Will the JVM load the package twice at runtime?
13. Can main method be declared final?
14. Describe synchronization in respect to multithreading.
15. Difference between HashMap and HashTable?
16. Difference between Swing and Awt?
17. Difference between Vector and ArrayList?
18. Do I need to import java.lang package any time? Why ?
19. Does garbage collection guarantee that a program will not run out of
20. Does importing a package imports the subpackages as well? e.g. Does importing com.MyTest.* also import com.MyTest.UnitTests.*?
21. Does Java provide any construct to find out the size of an object?
22. Explain different way of using thread?
23. Give a simplest way to find out the time a method takes for execution without using any profiling tool?
24. How are Observer and Observable used?
25. How are this() and super() used with constructors?
26. How can I customize the seralization process? i.e. how can one have a control over the serialization process?
27. How can one prove that the array is not null but empty using one line of code?
28. How do I serialize an object to a file?
29. How does a try statement determine which catch clause should be used to handle an exception?
30. How does an exception permeate through the code?
31. How does Java handle integer overflows and underflows?
32. How many objects are created in the following piece of code?
33. How to create custom exceptions?
34. If I do not provide any arguments on the command line, then the String array of Main method will be empty or null?
35. If I want an object of my class to be thrown as an exception object, what should I do?
36. If I write return at the end of the try block, will the finally block still execute?
37. If I write System.exit (0); at the end of the try block, will the finally block still execute?
38. If my class already extends from some other class what should I do if I want an instance of my class to be thrown as an exception object?
39. Is delete a keyword in Java?
40. Is Empty .java file a valid source file?
41. Is exit a keyword in Java?
42. Is it necessary that each try block must be followed by a catch block?
43. Is main a keyword in Java?
44. Is next a keyword in Java?
45. Is String a primitive data type in Java?
46. MyClass c1, c2, c3;
47. Objects are passed by value or by reference?
48. on declared items qualified by these modifiers.
49. Primitive data types are passed by reference or pass by value?
50. State the significance of public, private, protected, default modifiers both singly and in combination and state the effect of package relationships
51. System.out.println ("1" + 3);
52. What are Checked and UnChecked Exception?
53. What are checked exceptions?
54. What are different types of inner classes?
55. What are pass by reference and passby value?
56. What are runtime exceptions?
57. What are some alternatives to inheritance?
58. What are synchronized methods and synchronized statements?
59. What are synchronized methods and synchronized statements?
60. What are the different scopes for Java variables?
61. What are the different ways to handle exceptions?
62. What are the steps in the JDBC connection?
63. What are wrapper classes?
64. What does it mean that a method or field is "static"? ?
65. What environment variables do I need to set on my machine in order to be able to run Java programs?
66. What happens if you dont initialize an instance variable of any of the primitive types in Java?
67. What happens to the static fields of a class during serialization?
68. What if I do not provide the String array as the argument to the method?
69. What if I write static public void instead of public static void?
70. What if the main method is declared as private?
71. What if the static modifier is removed from the signature of the main method?
72. What is an abstract class?
73. What is an Iterator?
74. What is daemon thread and which method is used to create the daemon thread?
75. What is Externalizable interface?
76. What is Externalizable?
77. What is final?
78. What is HashMap and Map?
79. What is Overriding?
80. What is serialization?
81. What is static in java?
82. What is synchronization and why is it important?
83. What is the basic difference between the 2 approaches to exception handling...1> try catch block and 2> specifying the candidate exceptions in the throws
84. What is the catch or declare rule for method declarations?
85. What is the common usage of serialization?
86. What is the default value of an object reference declared as an instance variable?
87. What is the default value of the local variables?
88. What is the difference between a constructor and a method?
89. What is the difference between a while statement and a do statement?
90. What is the difference between an Interface and an Abstract class?
91. What is the difference between declaring a variable and defining a variable?
92. What is the difference between error and an exception??
93. What is the difference between preemptive scheduling and time slicing?
94. What is the difference between preemptive scheduling and time slicing?
95. What is the difference between static and non-static variables?
96. What is the first argument of the String array in main method?
97. What is the Locale class?
98. What is the purpose of finalization?
99. What is the purpose of garbage collection in Java, and when is it used?
100. What method must be implemented by all threads?
101. What modifiers are allowed for methods in an Interface?
102. What one should take care of while serializing the object?
103. What type of parameter passing does Java support?
104. What will be the default values of all the elements of an array defined as an instance variable?
105. What will be the initial value of an object reference which is defined as an instance variable?
106. What will be the output of the following statement?
107. When a thread is created and started, what is its initial state?
108. When should you use which approach?
109. When you serialize an object, what happens to the object references included in the object?
110. Which methods of Serializable interface should I implement?
111. Why do we need wrapper classes?