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
x
public class OuterClass { public void myMethod() { // Anonymous inner class implementing an interface Runnable r = new Runnable() { 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 Abstract Class
2: Anonymous Class With Interface
xxxxxxxxxxabstract class A8 { void m1() { System.out.println("m1-A"); } abstract void m2(); abstract 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() { //polymorphism happened here public void m2() { System.out.println("m2-A"); } public void m3() { System.out.println("m3-A, Hello"); } }; //end of anonymous inner class a.m1(); a.m2(); a.m3(); }}Output
m1-A
m2-A
m3-A, Hello
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