JAVA EE: Java Tutorial : Java Nested Interface(Inside Class)

Friday, 15 January 2016

Java Tutorial : Java Nested Interface(Inside Class)

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Java Tutorial : Java Nested Interface(Inside Class)

OuterClass.java

public class OuterClass
{
    void outerMethod()
    {
        System.out.println("Outer method has been called");
    }
    
    public interface NestedInterface
    {
        void nestedMethod();
    }
}

MyClass.java

/*
 * As you can see in the below example, we are accessing the 
 * NestedInterface by its OuterClass because 
 * it cannot be accessed directly. 
 * 
 * It is just like apple inside the box, we cannot access the apple directly 
 * because we must open the box first. 
 * 
 * In collection framework has provided a nested interface 
 * Entry. Entry is the sub-interface of Map i.e. accessed by Map.Entry.
 */

public class MyClass implements OuterClass.NestedInterface
{

    @Override
    public void nestedMethod()
    {
        System.out.println("Nested Method has been called.");

    }

}

InterfaceTest.java

public class InterfaceTest
{

    public static void main(String[] args)
    {
        OuterClass.NestedInterface nestedInterfaceRef = new MyClass();
        nestedInterfaceRef.nestedMethod();
    }

}

Output