Top 142 Core Java Interview Questions

Top 142 Core Java Interview Interview Questions:
1. What is the difference between an Abstract class and Interface ?
2. What is user-defined exception ?
3. What do you know about the garbage collector ?
4. What is the difference between java and c++ ?
5. In an HTML form I have a button, which makes us to open another page in 15 seconds. How will you do that ?
6. What is the difference between process and threads ?
7. What is update method called ?
8. Have you ever used HashTable and Directory ?
9. What are statements in Java ?
10. What is a JAR file ?
11. What is JNI ?
12. What is the base class for all swing components ?
13. What is JFC ?
14. What is the difference between AWT and Swing ?
15. Considering notepad/IE or any other thing as process, What will happen if you start notepad or IE 3 times ?
Where three processes are started or three threads are started ?
16. How does thread synchronization occur in a monitor ?
17. Is there any tag in HTML to upload and download files ?
18. Why do you canvas ?
19. How can you know about drivers and database information ?
20. What is serialization ?
21. Can you load the server object dynamically ?
If so what are the 3 major steps involved in it ?
22. What is the layout for toolbar ?
23. What is the difference between Grid and Gridbaglayout ?
24. How will you add panel to a frame ?
25. Where are the card layouts used ?
26. What is the corresponding layout for card in swing ?
27. What is light weight component ?
28. Can you run the product development on all operating systems ?
29. What are the benefits if Swing over AWT ?
30. How can two threads be made to communicate with each other ?
31. What are the files generated after using IDL to java compiler ?
32. What is the protocol used by server and client ?
33. What is the function ability stubs and skeletons ?
34. What is the mapping mechanism used by java to identify IDL language ?
35. What is serializable interface ?
36. What is the use of interface ?
37. Why is java not fully objective oriented ?
38. Why does java not support multiple inheritance ?
39. What is the root class for all java classes ?
40. What is polymorphism ?
41. Suppose if we have a variable 'I' in run method, if I can create one or more thread each thread will occupy a separate copy or same variable will be shared ?
42. What are virtual functions ?
43. Write down how will you create a Binary tree ?
44. What are the traverses in binary tree ?
45. Write a program for recursive traverse ?
46. What are session variable in servlets ?
47. What is client server computing ?
48. What is constructor and virtual function ?
Can we call a virtual function in a constructor ?
49. Why do we use oops concepts ?
What is its advantage ?
50. What is middleware ?
What is the functionality of web server ?
51. Why is java not 100% pure oops ?
52. When will you use an interface and abstract class ?
53. What is the exact difference in between Unicast and Multicast object ?
Where will it be used ?
54. What is the main functionality of the remote reference layer ?
55. How do you download stubs from Remote place ?
56. I want to store more than 10 objects in a remote server ?
Which methodology will follow ?
57. What is the main functionality of Prepared Statement ?
58. What is meant by Static query and Dynamic query ?
59. What are Normalization Rules ?
Define Normalization ?
60. What does Servelet mean ?
What are the parameters of service method ?
61. What is meant by Session ?
Explain something about HTTP Session Class ?
62. In a container there are 5 components. I want to display all the component names, how will you do that ?
63. Why there is some null interface in JAVA ?
What does it mean ?
Give some null interface in JAVA ?
64. Tell some latest versions in JAVA related areas ?
65. What does class loader mean ?
How many types are there ?
When will we use them ?
66. What does flickering mean ?
67. What is meant by distributed application ?
Why are we using that in our application ?
68. What is the functionality of the stub ?
69. Explain about version control ?
70. Explain 2-tier and 3-tier architecture ?
71. What is the role of Web Server ?
72. How can we do validation of the fields in a project ?
73. What is meant by cookies ?
Explain the main features ?
74. Why java is considered as platform independent ?
75. What are the advantages of java over C++ ?
76. How java can be connected to a database ?
77. What is thread ?
78. What is difference between Process and Thread ?
79. Does java support multiple inheritance ?
if not, what is the solution ?
80. What are abstract classes ?