Anonymous Inner Class in Funcational Interface

Anonymous Inner Class

Anonymous inner class is without having any name such type of class is called anonymous inner class.

Example 1.

Runnable    r = new Runnable (){

              public void run () {

}

}

Note: -

1. Anonymous inner class that extends concreate class.
2. Anonymous inner class that extends Abstract class.
3. We can declare instance variable with in the anonymous inner class.
4. Anonymous inner class is not equal to Lambda expression.

Note:- this.x always refers to inner variable in anonymous inner class.

interface InterfB{

     

      public void m1();

}

public class TestAnonymous {

      int x=10;

      public void m2(){

            InterfB interfB = new InterfB() {

                 

                   int x=20;

                 

                  @Override

                  public void m1() {

                       

                        System.out.println(this.x);

                  }

            };

            interfB.m1();

      }

     

      public static void main(String[] args) {

           

            TestAnonymous testAnonymous = new TestAnonymous();

            testAnonymous.m2();

      }

}

Result:- 20

Note:- this.x lambda expression refers outer variable only.

Example 2.

interface interfC{

      public void m1();

}

public class TestwithLambda {

      int x=10;

      public void m2(){

            interfC i =  ()->{

                  int x=20;        

                        System.out.println(this.x);  

                 

            };

            i.m1();    

      }

      public static void main(String[] args) {

            TestwithLambda lambda = new  TestwithLambda();

            lambda.m2();

      }

}

Result:-10

Example 3. With Anonymous function using Thread.

public class ThreadWithAnonymousDemo {


public static void main(String[] args) {

Thread t= new Thread(()->System.out.println("Child Thread"));
t.start();
for(int i=0; i<10; i++){
System.out.println("Main Thread");
}
}
}

Example 4. With Lambda Expression.

public class ThreadWithAnonymousDemoUsingLambda {

public static void main(String[] args) {

Runnable r = new Runnable(){

@Override
public void run() {
for(int i=0; i<10; i++){
System.out.println("Child Thread");
}

}

};

Thread t = new Thread(r);
}
}

Example : 5. How to use annonymous funcation in Lambda Expression.

Difference between Anonymous inner class and Lambda Expression

Anonymous inner Class

1.   It is a class without name.
2.   Anonymous inner class can extends Abstract class and Concrete classes.
3.   Anonymous inner class can implements as interface that contains any number of abstract methods;
4.   Inside Anonymous inner class We can declare instance variable.
5.   Anonymous inner class can be instantated.

Lambda Expression

1.     It is function without name (Anonymous function).
2.     Lambda Expression can’t extends Abstract class and Concrete classes.
3.     Lambda Expression can implement as interface which contains single abstract method(Functional        Interface) .
4.     Inside Lambda Expression we can declare instance variable what ever variable declared are         consider as local variables.
5.      Lambda Expression cannot be instantiated.

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Sudhir Kumar