why would we want to use interface in java code example

Example 1: interface in java

/* File name : MammalInt.java */
public class MammalInt implements Animal {

   public void eat() {
      System.out.println("Mammal eats");
   }

   public void travel() {
      System.out.println("Mammal travels");
   } 

   public int noOfLegs() {
      return 0;
   }

   public static void main(String args[]) {
      MammalInt m = new MammalInt();
      m.eat();
      m.travel();
   }
}

Example 2: java interface

public interface Exampleinterface {
	
  public void menthod1();
  
  public int method2();

}

class ExampleInterfaceImpl implements ExampleInterface {


  	public void method1()
    {
        //code here
    }
  
    public int method2()
  	{
    	//code here
  	}

}