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Abstract Class Vs Interface Java

Abstract Class Vs Interface Java

May 14th, 2019

Abstract class Vs interface java

An Abstract Class can be termed so on the declaration of the user. It is however not mandatory for an abstract class to have the abstract methods included in it. The abstract class delivers implementations when it is sub-classed. Interface in Java, on the other hand, is like a class that exclusively contains the fields and signatures. The difference is that it cannot deliver the implantations.

Why Abstract Class?

Abstract class is important because it helps the developers to create software programs that can be totally flexible. However, in the grassroot level, it cannot deliver any kind of convenience to the developers. Abstract class ensures that the software can be changed easily in the future. No matter in which language the developer writes a program like Java or C++ the abstract class is able to work with any languages.

It enhances Polymorphism which can be useful for the developer as he can make the needful changes. The abstract class can easily make use of the   inheritance. A good developer always uses the abstract class to make the top-notch software.  The developer should mandatorily know about the motive with which he is using the abstract class. With the abstract class, several types of classes can be made by numerous easy commands.

Sub-classes can be also made lucidly with the abstract class. It is also useful for a developer as it can be easily used that setting up an interface in Java. The programs are easy to be implemented in case of the abstract class. A developer might choose custom implementation also while using the abstract class. As multiple inheritance is  not supported by java, one can go  for the interface  too.

Why Interface Java?

The keyword of interface in Java is used for making the declaration of the annotation type. It can easily used to change the design of the software. It contains only the signature related to the software making method. The interface java is actually a group of abstract classes that the programmer puts to the use. A developer can also find several methods of the static and default type.

The nested type method is also found in case of an interface. Interface Java is mainly used by the developers to set up a communication process between couples of objects. In case of the communication already made, no specific implementation can be made by the two objects.

The software developers can easily extract out the multiple inheritance with the help of interface. Loose coupling can also be achieved in case of the usage of the interface. Like the abstract class, it can also deliver polymorphism up to a certain level. One can also expect some flexibly from the interface java too.

Difference Between Abstract Class and Interface Java

Abstract Class


Abstract class is not able to support any multiple inheritances.

Interface java can support the multiple inheritances.

Abstract class can deliver the implementation of the interface lucidly.

Interface is not able to provide the implementation to the to a abstract class.

Abstract class can have both the non-abstract and abstract method.

The interface java only has the abstract methods. Static and default methods are incorporated in the Java 8.

Extension of the abstract class can be done with the keyword ‘extends’.

Interface class can be easily implemented with the usage of the keyword like ‘implements’.

In case of the abstract class the abstract keyword is necessary.

A developer needs an interface keyword for the declaration.

Both public and protected abstract methods can be present in the case of abstract class.

Only public abstract methods can be present in case of the interface.


 Only a single abstract class can be extended from the pre-extended one.

Multiple numbers of interfaces can be extended from one interface.


Abstract class can have both static final and static final variable along with any access specified.

Only the constant variable can be found in case of the interface.


The abstract class might seem to be useless in the grassroot level; however, it can be used for more complicated software writing.

 An Interface might seem to be useful to the developers from the grassroot level of the software writing.

In case of the abstract class, the keyword declaration is mandatory.

In case of the interface ‘abstract’ declaration is optional.