An interface in Java programming language is an abstract type that is used to specify an interface (in the generic sense of the term) that classes must implement. Interfaces are declared using the interface keyword, and may only contain method signature and constant declarations. All methods of an Interface do not contain implementation. Interfaces cannot be instantiated, but rather are implemented. A class that implements an interface must implement all of the methods described in the interface, or be an abstract class.
Syntax
interface Interface_name{
//Do something with any number of final, static fields or any number of abstract methods
}
Interface Example Program
interface Main{
public void display();
public void disp();
}
class InterfaceDemo implements Main{
public void display(){
System.out.println("First implementation");
}
public void disp(){
System.out.println("Second implementation");
}
public static void main(String arg[]){
Main obj = new InterfaceDemo();
obj. display();
obj.disp();
}
}
Sample Output
Output is:
First implementation
Second implementation
