JAVA INTERFACE RULES HOW TO
JAVA INTERFACE RULES CODE

An interface is not extended by a class it is implemented by a class.

The only fields that can appear in an interface must be declared both static and final. An interface cannot contain instance fields.All of the methods of an interface are abstract.An interface does not contain any constructor.How the interface is different from a class in Java?Īn interface is different from a class in the following ways:

JAVA INTERFACE RULES CODE

Interfaces appear in packages and their corresponding byte code file must be in a directory structure that matches the package name.

The byte code of an interface appears in a.

java extension, with the name of the interface matching the name of the file.

An interface is written in a file with a.

An interface can contain any number of methods like class.

If we don’t provide these keywords compiler places these keywords automatically How the interface is similar to a class in Java?Īn interface is similar to a class in the following ways:

By default, the interface members are public static final variables and public abstract methods.Default access specifier of interface member is public.The default access specifier of the interface is the package.The interface doesn’t have any superclass/interface.Points to Remember while working with Interfaces in Java: ('The volume of Circle is : ' + s2.Volume ()) ('The area of Circle is : ' + s2.Area ()) ('The volume of Cube is : ' + s1.Volume ()) ('The area of Cube is : ' + s1.Area ()) Now in the main method class, we will create an instance and consume the two methods as shown in the below code. we will implement the two abstract methods (Cube and Circle) of the Shape interface as shown in the below code. Now we will create two classes (Cube and Circle) and then we will implement the Shape interface i.e. interface ShapeĪs you can see, here, we created the interface with two methods (Area and Volume). Let us first create an interface with the name Shape and then copy and paste the following code into it. Let us see an example to understand how the interface is used in the java application. Let us check what happens when we compile and execute itĮxception in thread “main” : main Interface Example in Java: We can compile the interface but we cannot execute it because it does not have the main method. Save the above interface in a file Example.java. Here the keyword interface tells that Example is an interface containing two final fields such as x and name and one abstract method such as show().īy default, the members of an interface are abstract and final means abstract methods and final fields.

JAVA INTERFACE RULES HOW TO

How to declare an interface in Java?īy using the keyword interface you can declare a class type of interface. If this is not clear at the moment, then don’t worry we will discuss this in detail with an example. If we define an abstract class in place of an interface, a service provider cannot implement multiple specifications so the service providers cannot have multiple businesses. So we must use the interface as a superclass to develop abstraction for supporting multiple inheritances. Java doesn’t support multiple inheritances with classes. What is the need for the interface when we already have abstract classes to define abstract methods? Now, you may have the following question in your mind. In our previous article, we already discussed that abstract method means method without body or implementation. So, you can consider it is a pure abstract class that allows you to define only public static final variables and public abstract methods. The interface is a fully un-implemented class used for declaring a set of operations of an object. The class that implements an interface must implement all the methods of that interface. Since methods in interfaces do not have a body, they have to be implemented by the class before you can access them. Note: It can be used to achieve loose coupling. That’s why java provides an alternative approach known as the interface to support the concept of multiple Inheritance. Since a large no of real-time applications are required for the use of multiple inheritances where we inherit properties from several different classes. For example a definition like the below.īut this concept is not supported by java with classes.

We know the concept of multiple inheritances where one class is derived from more than one superclass. At the end of this article, you will understand what is Interface in Java is and its need as well as when and how to use the Interfaces in Java with Examples. Please read our previous where we discussed Abstract Class and Abstract Methods in Java with Examples. In this article, I am going to discuss Interface in Java with Examples. Data Structures and Algorithms Tutorialsīack to: Java Tutorials For Beginners and Professionals Interface in Java with Examples.

Java interface rules