Core Java Interview Questions & Answers

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Narayanaswamy Ragi

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Thu, 21-Mar-2024

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91. What is java byte code?
92. What is method overloading?
93. What is method overriding?
94. What is finalize() ?
95. What is multi-threading?
96. What is deadlock?
97. What is the difference between Iterator and Enumeration?
98. What is the Locale class?
99. What is internationalization?
100. What is anonymous class ?
101. What is the difference between URL and URLConnection?
102. What are the two important TCP Socket classes?
103. Strings are immutable. But String s="Hello"; String s1=s+"World" returns HelloWorld how?
106. What is java collections?
107. Can we compile a java program without main?
108. What is a java compilation unit.
109. What are the restrictions when overriding a method ?
110. What is static initializer block? What is its use?
111. How does a try statement determine which catch clause should be used to handle an exception?
112. How parameters are passed to methods in java program ?
113. If a class doesn't have any constructors, what will happen?
114. What will happen if a thread cannot acquire a lock on an object?
115. How does multithreading occurring on a computer with a single CPU?
116. What will happen if you are invoking a thread's interrupt method while the thread is waiting or sleeping?
117. What are the different ways in which a thread can enter into waiting state?
118. What are the the different ways for creating a thread?
119. What is the difference between creating a thread by extending Thread class and by implementingRunnable interface? Which one should prefer?
120. What is coupling?
136. Why Java is not 100% pure object oriented language?
137. Why ArrayList is faster than Vector?
138. What is the security mechnaism used in java?
139. What is sandbox?
140. What is phantom memory?
141. What is reflection?
142. What are the differences between JIT and HotSpot?
143. What are the advantages and disadvantages of reference counting in garbage collection?
144. How would you implement a thread pool?
145. What is the difference between throw and throws clause?
147. What is a classloader?
148. What is the difference between Comparable and Comparator ?
149. What is the difference between List, Set and Map?
150. What is the difference between Exception and Error?
151. What is meant by Open Source?
152. How do you send data from an applet to Servlet ? What are the steps involved in it?
153. What is polymorphism?
154. What is a class, member and local variable?
155. How do I convert a numeric IP address like 66.29.36.130 into a hostname like www.javacertificate.net ?
92. What is method overloading?
156. What is the difference between a constructor and a method?
1. Why threads block or enters to waiting state on I/O?
2. What is List interface?
3. What is the difference between yield() and sleep()?
4. What are Wrapper Classes ?
5. Can we call finalize() method ?
6. What is the difference between time slicing and preemptive scheduling ?
7. What is the initial state of a thread when it is created and started?
8. Can we declare an anonymous class as both extending a class and implementing an interface?
9. What are the differences between boolean && operator and & operator?
10.What is the use of the finally block?
11. What is an abstract method ?
12. What is the difference between System.err and System.out?
13. What are the differences between an abstract class and an interface?
14. What is the difference between synchronized block and synchronized method?
15. How can you force garbage collection in java?
16. How can you call a constructor from another constructor ?
17. How can you call the constructor of super class ?
18. What's the difference between normal methods and constructors?
19. What is the use of packages in java ?
20. What must be the order of catch blocks when catching more than one exception?
25. How can we call a method or variable of the super class from child class ?
26. If you are overriding equals() method of a class, what other methods you might need to override ?
27. How can you create your own exception?
28. What is serialization?
29. What is de-serialization?
30. What is externalizable?
31. Does garbage collection guarantee that a program will not run out of memory?
32. What is a native method?
33. What are different type of exceptions in Java?
34. Can we catch an error in our java program ?
35. What is thread priority?
36. How many times may an object's finalize() method be invoked by the garbage collector?
37. What is the difference between a continue statement and a break statement?
38. What must a class do to implement an interface?
39. What is an abstract class?
40. What is the difference between notify and notifyAll method ?
41. What does wait method do ?
42. What are the different states of a thread?
43. What is the difference between static and non static inner class?
44. What is the difference between String and StringBuffer class ?
45. Which is the base class for all classes?
46. What is the difference between readers and streams?
47. What is constructor chaining?
48. What are the different primitive data types in java?
49. What is static?
50. Why we cannot override static methods?
51. What is the difference between static and non static variables?
52. When does a compiler supplies a default constructor for a class?
53. What are the restrictions placed on overriding a method ?
54. What are the restrictions placed on overloading a method?
55. What is casting?
56. What is the difference between == and equals?
57. What is a void return type ?
58. What will happen if an exception is not caught ?
59. What are the different ways in which a thread can enter into waiting state?
60. What is a ResourceBundle class?
60. What is a ResourceBundle class?
61. What is numeric promotion?
62. What is the difference between the prefix and postfix forms of the ++ operator?
63. What are synchronized methods and synchronized statements?
64. How can we create a thread?
65. What is the difference between a switch statement and an if statement?
66. What is hashCode?
67. What is an I/O filter?
What is the difference between RandomAccessFile and File?
69. What is final ?
70. What is the difference among JVM Spec, JVM Implementation, JVM Runtime?
71. How is the difference between thread and process?
72. What is the difference between Vector and ArrayList ?
73. What is the difference between Hashtable and HashMap ?
74. What are the access modifiers available in Java.
75. Why java is said to be pass-by-value ?
76. What do you mean by immutable ? How to create an immutable object?
77. What is class loader in java ?
78. What is a weak reference?
79. What is object cloning?
80. What is object pooling?
81. What is garbage collection?
81. What is garbage collection?
82. What is the disadvantage of garbage collection?
83. What is a Dictionary?
84. What is JAR file ?
85. Why Java is not fully objective oriented ?
86. What is a marker interface ?
87. What are tag interfaces?
88. What are the restrictions placed on static method ?
89. What is JVM?
90. What is JIT?

Narayanaswamy Ragi

Senior Security Analyst - Identity And Access Management - ForgeRock

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Core Java Interview Questions & Answers

Course description

What will i learn?

Requirements

Narayanaswamy Ragi

₹0

Lectures

137

Skill level

Intermediate

Expiry period

Lifetime

Certificate

Yes

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Core Java Interview Questions & Answers

Course description

What will i learn?

Requirements

Basics 137 Lessons Hours

core java besics 0 Lessons Hours

Narayanaswamy Ragi

₹0

Lectures

137

Skill level

Intermediate

Expiry period

Lifetime

Certificate

Yes

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