Want to know about how to implement the concepts.

4. operator overloading

public static void main(String[] args) {
final String first = "length: 10";
final String second = "length: " + first.length();
System.out.println("first and second are equal: " + first == second);
}

or click this link

http://www.javajee.com/operator-plus-overloading-in-java

3.method overloading

1. class Calculation{
2. void sum(int a,int b){System.out.println(a+b);}
3. void sum(int a,int b,int c){System.out.println(a+b+c);}
4. 
   
5. public static void main(String args[]){
6. Calculation obj=new Calculation();
7. obj.sum(10,10,10);
8. obj.sum(20,20);
9. 
   
10. }
11. }

or view this link

http://www.javatpoint.com/method-overloading-in-java

2.interface

interface s
{
void print();
}
interface c extends s
{
void msg();
}

class R implements c
{
public void print()
{
System.out.println("Hello Print");
}
public void msg()
{
System.out.println("Hello Msg");
}

public static void main(String args[])
{
R d=new R();
d.print();
d.msg();
}
}

1.abstract class

1. abstract class Bike{
2. abstract void run();
3. }
4. class Honda4 extends Bike{
5. void run(){System.out.println("running safely..");}
6. public static void main(String args[]){
7. Bike obj = new Honda4();
8. obj.run();
9. }
10. }