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Introduction to Java and Python Programming

Java Interview Questions

  • 01. What is a "transient" variable?
  • 02. What is a polymorphism?
  • 03. What are wrapper classes?
  • 04. What is the purpose of garbage collection in Java, and when is it used?
  • 05. What is the default value of byte datatype in Java?
  • 06. List primitive Java types?
  • 07. What are the principle concepts of OOPS?
  • 08. What is difference between ArrayList and LinkedList?
  • 09. What is the difference between StringBuffer and StringBuilder?
  • 10. What is the difference between error and an exception?
  • 11. Explain runtime exceptions?
  • 12. What is a "serialization"?
  • 13. What is difference between HashMap and Hashtable?
  • 14. What is an exception?
  • 15. What is a class variable?
  • 16. What is a method overloading?
  • 17. Why do we need wrapper classes?
  • 18. What is an encapsulation?
  • 19. What is the difference between String and StringBuffer?
  • 20. What is a "static" in java?
  • 21. What is the difference between Abstraction and Encapsulation?
  • 22. What do you mean by access modifier?
  • 23. What is the default value of the local variables?
  • 24. What is a "native" method?
  • 25. What is a "final"?
  • 26. What is an abstraction?
  • 27. Describe synchronization in respect to multithreading.
  • 28. What is the default value of float and double datatype in Java?
  • 29. What is a class in Java?
  • 30. What is an inheritance?
  • 31. What is a package in Java?
  • 32. What is the difference between a while statement and a do while statement?
  • 33. Why StringBuffer called mutable?
  • 34. What is an interface?
  • 35. What is the difference between an Interface and an Abstract class?
  • 36. What is an immutable object?
  • 37. What is an instance variable?
  • 38. What are checked and unchecked exceptions?
  • 39. What is difference between ArrayList and Vector?
  • 40. List any five features of Java?
  • 41. What do you mean by object?
  • 42. What kind of variables a class can consist of?
  • 43. What is difference between HashSet and HashMap?
  • 44. How many types of memory areas are allocated by JVM?
  • 45. What is the difference between declaring a variable and defining a variable?
  • 46. Do I need to import java.lang package any time? Why?
  • 47. What is a local variable?
  • 48. Why String class considered immutable?
  • 49. What is difference between HashMap and TreeMap?
  • 50. What is difference between HashSet and TreeSet?