Anonymous Inner Classes In Java

Anonymous Inner Classes

Definition:

Anonymous inner classes are a special type of inner class that does not have a name and is used to instantiate objects with certain methods or to override methods of a class or interface.

Key Points:

Anonymous inner classes are declared and instantiated all in one place.
They are often used in GUI applications for event handling or in scenarios where a one-time use implementation of an interface or subclass is required.

Use Cases:

Anonymous inner classes are useful when you need a short, one-time use class that either implements an interface or extends a class.
Commonly used in GUI frameworks like Swing for event handling, such as button clicks.

Code Example

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public class OuterClass {    public void myMethod() {        // Anonymous inner class implementing an interface        Runnable r = new Runnable() {            @Override            public void run() {                System.out.println("Anonymous Inner Class Running");            }        };​        // Running the anonymous inner class implementation        r.run();    }​    public static void main(String[] args) {        OuterClass outerObject = new OuterClass();        outerObject.myMethod();    }}

Output

Anonymous Inner Class Running

1: Anonymous Class With Interface

2: Anonymous Class With Abstract Class

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interface A8 {    void m1();    void m2();    void m3();}​public class Test8 {​    public static void main(String[] args)     {        // dont think that object is created for interface, for interfaces object is not created        // object is created for anonymous inner class        A8 a = new A8() {               @Override            public void m1()            {                System.out.println("m1-A");            }            @Override            public void m2()            {                System.out.println("m2-A");            }            @Override            public void m3()            {                System.out.println("m3-A");            }        }; //end of anonymous inner class        a.m1();        a.m2();        a.m3();    }}

Output

m1-A
m2-A
m3-A

Anonymous Inner Classes

Output

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