Core Java Interview Questions
Hello Friends, Nice to see you again.
After lots of post related to Java Swing, Here, I come with core java part for Question and Answers.
This is not something new that you will see.
But I had always used other websites and blogs to read this stuff.
Now, I think I should also share this with others.
So enjoy this post.
This is not something new that you will see.
But I had always used other websites and blogs to read this stuff.
Now, I think I should also share this with others.
So enjoy this post.
Questions on OOPS Concepts
1. What are the principle concepts of OOPS?
programming rest. They are:
Polymorphism
Inheritance
Encapsulation
(i.e. easily remembered as PIE).
2. What is Encapsulation?
Encapsulation is a technique used for hiding the properties and
behaviors of an object and allowing outside access only as
appropriate. It prevents other objects from directly altering or
accessing the properties or methods of the encapsulated object.
3. What is Inheritance?
Inheritance is the process by which objects of one class acquire
the properties of objects of another class.
A class that is inherited is called a superclass.
The class that does the inheriting is called a subclass.
Inheritance is done by using the keyword extends.
The two most common reasons to use inheritance are:
1. To promote code reuse
2. To use polymorphism
4. What is Polymorphism?
Polymorphism is briefly described as "one interface, many
implementations."
Polymorphism is a characteristic of being able to assign a different
meaning or usage to something in different contexts - specifically,
to allow an entity such as a variable, a function, or an object to
have more than one form.
5. What is run-time polymorphism or dynamic method dispatch?
In Java, run-time polymorphism or dynamic method dispatch is
a process in which a call to an overridden method is resolved
at run-time rather than at compile-time.
In this process, an overridden method is called through the
reference variable of a superclass. The determination of the method
to be called is based on the object being referred to by the reference
variable.
6. What is method overloading?
Method Overloading means to have two or more methods with same
name in the same class with different arguments. The benefit of
method overloading is that it allows you to implement methods
that support the same semantic operation but differ by argument
number or type.
Note:
Overloaded methods MUST change the argument list
Overloaded methods CAN change the return type
Overloaded methods CAN change the access modifier
Overloaded methods CAN declare new or broader checked exceptions
A method can be overloaded in the same class or in a subclass
name in the same class with different arguments. The benefit of
method overloading is that it allows you to implement methods
that support the same semantic operation but differ by argument
number or type.
Note:
Overloaded methods MUST change the argument list
Overloaded methods CAN change the return type
Overloaded methods CAN change the access modifier
Overloaded methods CAN declare new or broader checked exceptions
A method can be overloaded in the same class or in a subclass
7. What is method overriding?
Method overriding occurs when sub class declares a method that has
the same type arguments as a method declared by one of its
superclass.
The key benefit of overriding is the ability to define behavior that’s
specific to a particular subclass type.
Note:
* The overriding method cannot have a more restrictive access
modifier than the method being overridden (Ex: You can’t override
a method marked public and make it protected).
* You cannot override a method marked final
* You cannot override a method marked static.
8. Is it possible to override the main method?
No.