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.
Answer : A
Explaination
The byte data type is represented by an 8-bit signed two's complement integer.
Minimum value: -128
Maximum value: 127
Q 2 - What is the size of boolean variable?
Answer : B
Explaination
The boolean data type can take either true or false, but its "size" isn't precisely defined.
Answer : C
Explaination
long variable has default value of 0L if defined as an instance/static variable.
Q 4 - Which of the following is true about protected access modifier?
A - Variables, methods and constructors which are declared protected can be accessed by any class.
Answer : C
Explaination
Protected access modifier is used to restrict access to variables, methods and constructors to subclass only. Subclass can lie in different package.
Answer : B
Explaination
Inheritance represets IS-A relationship providing code reusablity . Consider the following statement: Circle is a Shape. Here Shape is super class and Circle is a child class extends the super class Shape.
Q 6 - What is Set Interface?
A - Set is a collection of element which contains elements along with their key.
B - Set is a collection of element which contains hashcode of elements.
C - Set is a collection of element which cannot contain duplicate elements.
D - Set is a collection of element which can contain duplicate elements.
Answer : C
Explaination
Set is a collection of element which cannot contain duplicate elements. The Set interface contains only methods inherited from Collection and adds the restriction that duplicate elements are prohibited.
Q 7 - What is NullPointerException?
B - A NullPointerException is thrown when object is set as null.
C - A NullPointerException is thrown when object property is set as null.
Answer : A
Explaination
A NullPointerException is thrown when calling the instance method of a null object or modifying/accessing field of a null object.
Q 8 - Does garbage collection guarantee that a program will not run out of memory?
Answer : B
Explaination
Garbage collection does not guarantee that a program will not run out of memory. It is possible for programs to use up memory resources faster than they are garbage collected. It is also possible for programs to create objects that are not subject to garbage collection.
Answer : B
Explaination
It is not necessary that each try block must be followed by a catch block. It should be followed by either a catch block or a finally block.
Q 10 - What is a marker interface?
A - marker interface is an interface with no method.
B - marker interface is an interface with single method, mark().
C - marker interface is an interface with single method, marker().
Answer : A
Explaination
Marker interface is an interface with no method.
