SCJP 5 : Chapter 1. Declarations, Initialization and Scoping (Part-6)

Non-static inner classes have a hidden reference to the enclosing class instance. This means you must have an instance of the enclosing class to create the inner class. You also have to use a special "new" function that correctly initializes the hidden reference to the enclosing class. The special "new" function is a member of the enclosing class.

public class InnerClassTest {             .

            .....public class ReallyInner {             

            ......}

            }

InnerClassTest o = new InnerClassTest();             

            InnerClassTest.ReallyInner i = o.new ReallyInner();

InnerClassTest.ReallyInner i = new InnerClassTest().new ReallyInner();

Example:

public class InnerClassTest {             

            ......public void foo() {             

            ............System.out.println("Outer class");             

            ......}

......public class ReallyInner {             

            ............public void foo() {             

            ..................System.out.println("Inner class");

            .............}

            public void test() {             

            ..................this.foo();             

            ..................InnerClassTest.this.foo();             

            ............}             

            ......}

............public static void main(String[] args) {             

            .................InnerClassTest.ReallyInner i = new 

            ....................InnerClassTest().new ReallyInner();

            ....................i.test();             

            ...........}             

            }

Output:

Inner class
Outer class

______________

Author: Mikalai Zaikin. Please Click Here to visit Authors site for any updates and changes to the study notes.

SCJP 5 : Chapter 1. Declarations, Initialization and Scoping (Part-6)

Creating Inner Classes Instances

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