Core Java - Interview Questions and Answers for 'Core Java' | Search Interview Question

Interview Questions and Answers - Order By Newest

Q1051. How is the virtual method table implemented in Java?

^{This question is still unanswered. Can you please provide an answer.}

Help us improve. Please let us know the company, where you were asked this question :

_{Like Discuss Correct / Improve virtual method table method overriding runtime polymorphism object oriented programming (oops) oops concepts expert rare}

Q1052. How many VTables are there for each class ?

Core Java

Ans. There is one VTable for each class.

Help us improve. Please let us know the company, where you were asked this question :

_{Like Discuss Correct / Improve virtual table method vtable runtime polymorphism object oriented programming (oops) oops concepts method overriding intermediate rare}

Q1053. Have you ever used java.util.Objects class ?

Core Java

Ans. Yes, We are using requireNonNull method for validating if the object is null.

Help us improve. Please let us know the company, where you were asked this question :

_{Like Discuss Correct / Improve objects util methods rare}

Q1054. Why do we use getbytes in Java?

Core Java

Ans. It is used to convert String into an array of bytes.

byte[] getBytes() - converts String into a byte array.

byte[] getBytes(Charset charset) - converts String to byte array, based on charset encoding.

Help us improve. Please let us know the company, where you were asked this question :

_{Like Discuss Correct / Improve}

Q1055. Can Java be run on hardware with just the JVM and no OS ?

Core Java

^{This question is still unanswered. Can you please provide an answer.}

Help us improve. Please let us know the company, where you were asked this question :

_{Like Discuss Correct / Improve}

Q1056. Which java feature is used to convert primitive type to reference type ?

Core Java

Ans. AutoBoxing

Help us improve. Please let us know the company, where you were asked this question :

_{Like Discuss Correct / Improve}

Q1057. What is a reflexive equals contract ?

Core Java

Ans. An equal contract is said to be reflexive is equality between 2 objects always returns to be true.

For example -

Object o1;
Object o2;

o1.equals(o2); // returns true
o2.equals(o1); //returns true

Help us improve. Please let us know the company, where you were asked this question :

_{Like Discuss Correct / Improve reflexive equals contract}

Q1058. Explain Transitive equals contract.

Core Java

Ans. The equals contract is said to be transitive if

obj1.equals(obj2); and obj2(.equals(obj3)

then obj1.equals(obj3) also returns true.

Help us improve. Please let us know the company, where you were asked this question :

_{Like Discuss Correct / Improve Transitive equals contract rare}

Q1059. How will you enable or disable assertion for a package during runtime ?

Core Java

^{This question is still unanswered. Can you please provide an answer.}

Help us improve. Please let us know the company, where you were asked this question :

_{Like Discuss Correct / Improve}

Q1060. Which java version supports assertion ?

Core Java

^{This question is still unanswered. Can you please provide an answer.}

Help us improve. Please let us know the company, where you were asked this question :

_{Like Discuss Correct / Improve}

Q1061. Create an event class in Java.

Core Java

^{This question is still unanswered. Can you please provide an answer.}

Help us improve. Please let us know the company, where you were asked this question :

_{Like Discuss Correct / Improve event class}

Q1062. How does multi threading improve performance ?

Core Java

Ans. Every process in it's timeline require different resources. Utilization of resources can be optimized when they are shared among different processes or threads. When one thread is sleeping waiting for a peripheral to complete (e.g. a disk write, or a key press from the keyboard), other threads can continue using processor time and hence would lead to better usage of resources.

Help us improve. Please let us know the company, where you were asked this question :

_{Like Discuss Correct / Improve multithreading threads basic frequent}

Q1063. What are the different ways to avoid multi Threading related problems in Java ?

Core Java

Ans. Synchronization,
Concurrent classes,
Volatile keyword,
Implementing concurrent Lock interface,
Immutable classes

Help us improve. Please let us know the company, where you were asked this question :

_{Like Discuss Correct / Improve multithreading threads ways to avoid thread related problems synchronization volatile concurrent collections Intermediate}

Q1064. What is context switching wrt Threads in Java?

Core Java

Ans. Context Switching is the process of storing and restoring of CPU state so that Thread execution can be resumed from the same point at a later point of time.

Help us improve. Please let us know the company, where you were asked this question :

_{Like Discuss Correct / Improve Threads multithreading context switching}

Q1065. What is Lock interface in Java Concurrency API ?

Core Java

Ans. Lock interface provide more extensive locking. They allow more flexible structuring and may support multiple associated Condition objects.

Help us improve. Please let us know the company, where you were asked this question :

_{Like Discuss Correct / Improve concurrency api}

Q1066. Why Concurrent Collection Classes are fail-fast in Java ?

Core Java

^{This question is still unanswered. Can you please provide an answer.}

Help us improve. Please let us know the company, where you were asked this question :

_{Like Discuss Correct / Improve concurrent collection classes fail fast fail-fast collections collection classes expert}

Q1067. Can a class extend itself in Java ?

Core Java

Ans. No

Help us improve. Please let us know the company, where you were asked this question :

_{Like Discuss Correct / Improve inheritance object oriented programming (oops) oops concepts}

Q1068. What is method hiding in Java ?

Core Java

^{This question is still unanswered. Can you please provide an answer.}

Help us improve. Please let us know the company, where you were asked this question :

_{Like Discuss Correct / Improve method hiding}

Q1069. Can you prevent overriding a method without using final modifier or without declaring it private ?

Core Java

^{This question is still unanswered. Can you please provide an answer.}

Help us improve. Please let us know the company, where you were asked this question :

_{Like Discuss Correct / Improve}

Q1070. Can we override a non-static method as static in Java ?

Core Java

Ans. No, there is no method overriding with static methods.

Help us improve. Please let us know the company, where you were asked this question :

_{Like Discuss Correct / Improve}

Q1071. Can we declare constructor inside an interface ? Why ?

Core Java

^{This question is still unanswered. Can you please provide an answer.}

Help us improve. Please let us know the company, where you were asked this question :

_{Like Discuss Correct / Improve interface constructor}

Q1072. Can we declare an Interface with abstract keyword ?

Core Java

Ans. Yes

Help us improve. Please let us know the company, where you were asked this question :

_{Like Discuss Correct / Improve abstract keyword}

Q1073. Does Java generate .class file for interfaces ?

Core Java

Ans. Yes

Help us improve. Please let us know the company, where you were asked this question :

_{Like Discuss Correct / Improve .class file java byte code interfaces}

Q1074. How arrays work internally ?

Core Java

^{This question is still unanswered. Can you please provide an answer.}

Help us improve. Please let us know the company, where you were asked this question :

_{Like Discuss Correct / Improve arrays}

Q1075. Can we change the size of array once created ?

Core Java

Ans. No. Arrays cannot resize dynamically.

Help us improve. Please let us know the company, where you were asked this question :

_{Like Discuss Correct / Improve array array size Basic}

Q1076. Can we use generics with arrays in Java ?

Core Java

Ans. No

Help us improve. Please let us know the company, where you were asked this question :

_{Like Discuss Correct / Improve}

Q1077. What is the difference between ArrayIndexOutOfBoundException and ArrayStoreException?

Core Java

^{This question is still unanswered. Can you please provide an answer.}

Help us improve. Please let us know the company, where you were asked this question :

_{Like Discuss Correct / Improve exception handling}

Q1078. What is ArrayStoreException ?

Core Java

Ans. It's an exception that is thrown when we attempt to add value of an incompatible type to an array.

For example -

Object[] strArray = new String[2];
strArray[0] = 5;

In this code, strArray reference of type Object has currently been assigned the String array but at line 2 we are trying to add an integer value.

Help us improve. Please let us know the company, where you were asked this question :

_{Like Discuss Correct / Improve arrays ArrayStoreException}

Q1079. What is an anonymous array in Java ?

Core Java

^{This question is still unanswered. Can you please provide an answer.}

Help us improve. Please let us know the company, where you were asked this question :

_{Like Discuss Correct / Improve anonymous arrays}

Q1080. What are jagged arrays ?

Core Java

Ans. an array of different sizes

Help us improve. Please let us know the company, where you were asked this question :

_{Like Discuss Correct / Improve arrays jagged arrays}

Search Interview Questions

Help us and Others Improve. Please let us know the questions asked in any of your previous interview.