Core Java Interview Questions

Java Interview Questions

Hello friends here i will give you some important Core Java Interview Questions related to core java and advance java.

1. What is Polymorphism?
2. What is JVM ?
3. What is JRE ?
4. What is Abstraction?
5. What is Abstract class?
6. When Abstract methods are used?
7. What is Encapsulation?
8. What is the primary benefit of Encapsulation?
9. What is an Interface?
10. Give some features of Interface?
11. Define Packages in Java?
12. Why use package in Java ?
13. Why Packages are used?
14. What do you mean by Multithreaded program?
15. What are the two ways in which Thread can be created?
16. What is an applet?
17. An applet extend which class?
18. Explain garbage collection in Java?
19. Define immutable object?
20. Explain the usage of this() with constructors?
21. Explain Set Interface?
22. What is market interface in Java ?
23. How to achieve multiple inheritance in Java ?
24. Explain TreeSet?
25. What is Comparable Interface?
26. What is JAR file?
27. What is a WAR file?
28. Define JIT compiler?
29. Explain main thread under Thread class execution?
30. Life cycle of an applet includes which steps?
31. Why is the role of init() method under applets?
32. Which method is called by Applet class to load an image?
33. Define code as an attribute of Applet?
34. Define canvas?
35. Define Network Programming?
36. What is a Socket?
37. Advantages of Java Sockets?
38. Disadvantages of Java Sockets?
39. Which class is used by server applications to obtain a port and listen for client requests?
40. Which class represents the socket that both the client and server use to communicate with each other?
41. Why Generics are used in Java?
42. What environment variables do I need to set on my machine in order to be able to run Java programs?
43. Difference between package and inheritance ?
44. Is there any need to import java.lang package?
45. What is Nested top-level class?
46. What is Externalizable interface?
47. If System.exit (0); is written at the end of the try block, will the finally block still execute?
48. How to implement interface in Java ?
49. What is thread ?
50. Explain life cycle of Thread ?