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Java Online Quiz

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.

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 - What is the size of char variable?

Answer : B

Explaination

The char data type is represented by single 16-bit Unicode character.

Minimum value: '\u0000' (or 0)

Maximum value: '\uffff' (or 65,535)

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

Answer : A

Explaination

int variable has default value of 0 if defined as an instance/static variable.

Q 4 - Which of the following is true about String?

A - String is mutable.

B - String is immutable.

C - String is a data type.

D - None of the above.

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.

Q 5 - What is inheritance?

A - It is the process where one object acquires the properties of another.

B - inheritance is the ability of an object to take on many forms.

C - inheritance is a technique to define different methods of same type.

D - None of the above.

Answer : A

Explaination

It is the process where one object acquires the properties of another. With the use of inheritance the information is made manageable in a hierarchical order.

Q 6 - What is TreeSet Interface?

A - It is a Set implemented when we want elements in a tree based order.

B - It is a Set implemented when we want elements in a sorted order.

C - It is a Set implemented when we want elements in a binary tree format.

D - It is a Set implemented when we want elements in a hiearchical order.

Answer : B

Explaination

TreeSet is a Set implemented when we want elements in a sorted order.

Q 7 - Method Overloading is an example of

A - Static Binding.

B - Dynamic Binding.

C - Both of the above.

D - None of the above.

Answer : A

Explaination

Method Overloading is example of static binding.

Q 8 - Which is the way in which a thread can enter the waiting state?

A - Invoke its sleep() method.

B - invoke object's wait method.

C - Invoke its suspend() method.

D - All of the above.

Answer : D

Explaination

A thread can enter the waiting state by invoking its sleep() method, by blocking on IO, by unsuccessfully attempting to acquire an object's lock, or by invoking an object's wait() method. It can also enter the waiting state by invoking its (deprecated) suspend() method.

Q 9 - Deletion is faster in LinkedList than ArrayList.

A - True.

B - False.

Answer : A

Explaination

Deletion in linked list is fast because it involves only updating the next pointer in the node before the deleted node and updating the previous pointer in the node after the deleted node.

Q 10 - This is the parent of Error and Exception classes.

Answer : A

Explaination

Throwable is the parent of both Error and Exception class.

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