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?
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.
Answer : A
Explaination
True, an empty .java file is a valid source file.
Answer : A
Explaination
char variable has default value of '\u0000' if defined as an instance/static variable.
Q 4 - Which of the following is true about String?
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 Encapsulation?
A - Encapsulation is a technique to define different methods of same type.
B - Encapsulation is the ability of an object to take on many forms.
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.
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.
Q 7 - Method Overriding is an example of
Answer : B
Explaination
Method Overriding is example of dynamic Binding.
Q 8 - What are Wrapper classes?
A - These are classes that allow primitive types to be accessed as objects.
B - These are classes that wraps functionality of an existing class.
Answer : A
Explaination
These are classes that allow primitive types to be accessed as objects. Example: Integer, Character, Double, Boolean etc.
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.
Q 10 - When finally block gets executed?
A - Always when try block get executed, no matter exception occured or not.
B - Always when a method get executed, no matter exception occured or not.
C - Always when a try block get executed, if exception do not occur.
Answer : A
Explaination
Always when try block get executed, no matter exception occured or not.
