implements_Keyword

implements Java Keyword with Examples

The implements keyword is used in a class declaration to indicate that the class being declared provides implementations for all methods declared in the interface whose name follows the implements keyword.

The following example illustrates a class implements an interface and provides a detailed implementation for the interface’s methods:

/**
 * This represents payment interface
 */
interface Payment {
    public void pay();
}

class CashPayment implements Payment {

    // method overriding
    @Override
    public void pay() {
        System.out.println("This is cash payment");
    }

}

class CreditPayment implements Payment {

    // method overriding
    @Override
    public void pay() {
        System.out.println("This is credit card payment");
    }
}

Unlike extends keyword, a class can implement multiple interfaces. The interface names are separated by commas. For example:

interface A {

}

interface B {

}

class C implements A, B {

}

Summary

• A single class may implement multiple interfaces.
• If the implemented class does not provide an implementation for the interface’s methods, the class must be abstract.