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Core Java InterView Questions

Core Java Interview Questions

Q1. Can we define static variables inside the static method or not?

Q2. In project when we will instance & static varaibles give the scenario

Q3. When we will use for vs. for-each

Q4. Define JDK vs. JRE vs. JVM

Q5. How many parts of java

Q6. What is the purpose of methods

Q7. Define class vs.Object

Q8. Define and(&),or()

Q9. Define the constructor

Q10. define break vs. continue

Q11. Define the package in java

Q12. What is the difference between bitwise & logical operator

Q13. What are the entry controlled loop & exit controll loop

Q14. When we will get StackOverflowError

Q15. Explain instance & static blocks What is the purpose of blocks

Q16. What are the different ways to load the .class file into memory

Q17. How to call the constructor in javaIs it one constructor can call multiple constructors

Q18. What is method recursion

Q19. What are the Different ways to call the static members in java

Q20. When we will use switch & else-if statements in Application

Q21. When we will use for vs. while loops in Application

Q22. Can we access the other packages classes without import statements

Q23. What is the difference between the normal import & static import

Q24. What are the modifiers applicable to constructors

Q25. Explain System.out.println()

Q26. Can we access sub-packages data when we import main package with

Q27. What are the PermissionScoping modifiers in java

Q28. Define inheritance how many types inheritance in java

Q29. Explain about Object class in java

Q30. Define the Polymorphism How many types of Polymorphisms in java

Q31. What are the Different types of overloading in java What is the advantage

Q32. What is method Overriding what is the advantage

Q33. What are the rules to fallow while overriding the method

Q34. What is Co-variant return type in java

Q35. What is Method overriding & method hiding in java

Q36. What is the advantage of parent class reference hilding the Child class object

Q37. Explain about final modifierprevention modifier in java

Q38. Define abstract methods & normal methods in java

Q39. Explain normal classes & abstract classes in java

Q40. what is the abstraction concept in java What is the advantage of abstraction

Q41. Explain about interfaces in java

Q42. What is the difference between interfaces & abstract classes & normal classes & client code

Q43. How to clone the objects in java What is the advantage

Q44. What the new features about interfaces in java

Q45. Explain about functional interfaces in java

Q46. What is the meaning of Automatic garbage collection

Q47. What are the Different ways to call the Garbage Collector

Q48. What are the Different ways to make the object un-referenced

Q49. Explain Encapsulation mechanism in java

Q50. What are the different ways to initialize the data in java explain

Q51. Define type conversion what are the different types of type conversions in java

Q52. Why method signature of main() method is always public static void main(String[] args)

Q53. Though interface is a pure abstract class then why interfaces are needed

Q54. Define the exception What is the main objective of exception handling

Q55. what are the types of exceptions in java

Q56. What are the differnet ways to handle the exceptions in java

Q57. What are the possible ways to handle the multiple exceptions in java

Q58. What is the purpose of try-with resources concept

Q59. What is the purpose of finally block

Q60. What is the purpose of throw keyword How to handle the userdefined exceptions in java

Q61.What are the difference ways to create String object

Q62. what is the difference == operator & equals() method

Q63. What is the difference between String vs. StringBuffer

Q64. What is the difference between equals() vs. compareTo()

Q65. What is the difference between StringBuffer & StringBuilder

Q66. What are the advanatges of Wrapper classes

Q67. Define Autoboxing & Auto-unboxing

Q68. What is the purpose of enum

Q69. What is the purpose of Annotation

Q70. How to perform read & write operations on text files & images

Q71. What are the difference between normal Streams & buffered streams

Q72. How to create & remove the files & directories in java

Q73. what are the advantages of nested classes in java

Q74. Define lambda expression in java

Q75. What is method reference concept in java

Q76. What is Reflection mechanism in java

Q77. What are the main components of JVM

Q78. Define the Thread What are the advantages of multithreading

Q79. What are the different ways to create a thread Explain start() run() methods

Q80. What’s the difference between class lock and object lock

Q81. Explain Daemon & non-Daemon threads in java

Q82. Explain thread names & priority in java

Q83. Explain sleep() vs. join() vs. wait()

Q84. What is the purpose of Assertions in java

Q85. Define the array what are the advantages of arrays

Q86. What is the main objective of Collection framework What are the parts in Collections fw

Q87. What are the difference between Collections & Arrays

Q88. What are the difference between List & Set

Q89. How to add one collection data into another

Q90. What are the Differences between ArrayList & LinkedList

Q91. What are the Differeent ways to read the data from collection classes

Q92. What is the purpose of cursor Explain the cursors in java

Q93. What are the conditions we need to fallow while sorting Collection data

Q94. what is the purpose of serialization & Desrialization process How to prevent serialization

Q95. What is Type Earser in java

Q96. What is the Difference between Comparable vs. Comparator

Q97. In application when we will use Map classes

Q98. What is the purpose of streams API in java

Q99. How to convert Arrays to Collections & Collections to Arrays

Q100. What is the purpose of WildCard symbol() in Generics

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