Java Online Quiz


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Following quiz provides Multiple Choice Questions (MCQs) related to Core Java. You will have to read all the given answers and click over the correct answer. If you are not sure about the answer then you can check the answer using Show Answer button. You can use Next Quiz button to check new set of questions in the quiz.

Questions and Answers

Q 1 - What of the following is the default value of an instance variable?

A - null

B - 0

C - Depends upon the type of variable

D - Not assigned

Answer : C

Explaination

Instance variables are assigned default values based on their types. For example, int variable is assigned 0 and an object type variable is assigned null as default value.

Q 2 - Is an empty .java file a valid source file?

A - True

B - False

Answer : A

Explaination

True, an empty .java file is a valid source file.

Q 3 - What is the default value of char variable?

A - '\u0000'

B - 0

C - null

D - not defined

Answer : A

Explaination

char variable has default value of '\u0000' if defined as an instance/static variable.

Answer : B

Explaination

String object is immutable so that once it is created a String object cannot be changed. Since String is immutable it can safely be shared between many threads which are considered very important for multithreaded programming.

Answer : C

Explaination

It is the technique of making the fields in a class private and providing access to the fields via public methods. If a field is declared private, it cannot be accessed by anyone outside the class, thereby hiding the fields within the class. Therefore encapsulation is also referred to as data hiding.

Q 6 - Composition represents

A - HAS-A relationship.

B - IS-A relationship.

Answer : A

Explaination

Holding the reference of the other class within some other class is known as composition. It represents a HAS-A relationship. For example, a Student has a Pen. Here Student class has Pen as its instance variable.

Answer : B

Explaination

Method Overriding is example of dynamic Binding.

Answer : A

Explaination

These are classes that allow primitive types to be accessed as objects. Example: Integer, Character, Double, Boolean etc.

Q 9 - Is it necessary that each try block must be followed by a finally block?

A - True.

B - False.

Answer : B

Explaination

It is not necessary that each try block must be followed by a finally block. It should be followed by either a catch block or a finally block.


java_questions_answers.htm

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