Core Java Interview Preparation Questions

Interview Questions Categories
Core Java | J2EE | Database | Struts | XML | HTTP | Web Services

I have prepared this list for those of you seeking to appear in Java interview at various companies globally. This post contains a list of core java questions. These are prepared from most frequently asked questions from various software industries. I myself have interviewed over 100 candidates. I have intentionally not provided the solution here. But if you are desperate for one, send me an email via Contact Us link. For other interview questions such as those for J2EE, XML, Database etc and for some sample programming implementations intended to help you to prepare for the interview of tech giants like Google  / Microsoft / Amazon, go to my page here.

The questions below are alphabetically sorted.

  1. Can you instantiate the Math class?
  2. Define Modularity?
  3. Describe synchronization in respect to multithreading. How do you do that Java?
  4. Does it matter in what order catch statements for FileNotFoundException and IOException are written?
  5. Does java support multiple inheritance?
  6. Explain Exception handling in Java.
  7. Explain the difference between overriding and overloading?
  8. Give an example of where you would use Interface not an Abstract Class and vice versa?
  9. How do you do bit manipulation, bitwise operation in Java?
  10. How is polymorphism achieved in java?
  11. How will you get the platform dependent values like line separator, path separator, etc., ?
  12. How will you invoke any external process in Java?
  13. How will you load a specific locale?
  14. In thread, which method resumes the first thread that went into sleep mode?
  15. Is JVM a compiler or an interpreter?
  16. Is Private Method or member variable available to the subclass in the same package?
  17. State the significance of protected and default modifiers.
  18. What are the approaches that you will follow for making a program very efficient?
  19. What are the core OOP’s concepts?
  20. What are the methods in Object?
  21. What does the finalize method do?
  22. What is a base class?
  23. What is a Class?
  24. What is a constructor?
  25. What is a daemon thread?
  26. What is a DatabaseMetaData?
  27. What is a destructor?
  28. What is a final class?
  29. What is a final method?
  30. What is a final variable?
  31. What is a package?
  32. What is a subclass?
  33. What is a superclass?
  34. What is aggregation?
  35. What is an Abstract Class?
  36. What is an Instance?
  37. What is an Interface?
  38. What is an Object?
  39. What is Class.forName() does and how it is useful?
  40. What is collaboration?
  41. What is composition
  42. What is composition?
  43. What is DriverManager?
  44. What is final?
  45. What is Finally? And give an example of how to use it?
  46. What is garbage collection? What is the process that is responsible for doing that in java?
  47. What is inner class?
  48. What is inheritance?
  49. What is JIT and its use?
  50. What is Locale?
  51. What is meant by abstraction?
  52. What is meant by Binding?
  53. What is meant by Dynamic binding?
  54. What is meant by Encapsulation?
  55. What is meant by Inheritance?
  56. What is meant by Object Oriented Programming?
  57. What is meant by Persistence?
  58. What is meant by Polymorphism?
  59. What is meant by static binding?
  60. What is mutable object and immutable object?
  61. What is nested class?
  62. What is pass by reference and pass by value?
  63. What is Polymorphism
  64. What is reflection?
  65. What is singleton?
  66. What is skeleton and stub? what is the purpose of those?
  67. What is static in java?
  68. What is the base class for Error and Exception?
  69. What is the basic difference between String and StringBuffer and StringBuilder object?
  70. What is the byte range?
  71. What is the difference between an Interface and an Abstract class?
  72. What is the final keyword denotes?
  73. What is the impact and usage of Static member variables in Multithreaded programs.
  74. What is the implementation of destroy method in java.. is it native or java code?
  75. What is the major difference between LinkedList and ArrayList?
  76. What is the purpose of assert keyword used in JDK1.4.x?
  77. What is the purpose of garbage collection in Java, and when is it used?
  78. What is the purpose of Void class?
  79. What is the significance of ListIterator?
  80. What kind of thread is the Garbage collector thread?
  81. What operator would you use to compare two String variables?
  82. When you think about optimization, what is the best way to find out the time/memory consuming process?

For other interview preparation questions and materials, go to my page here.

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