多态性

1.静态绑定/编译时绑定/早期绑定/方法重载。（在同一类中）

2.动态绑定/运行时绑定/后期绑定/方法重写（在不同的类中）

重载示例：

class Calculation {  
  void sum(int a,int b){System.out.println(a+b);}  
  void sum(int a,int b,int c){System.out.println(a+b+c);}  

  public static void main(String args[]) {  
    Calculation obj=new Calculation();  
    obj.sum(10,10,10);  // 30
    obj.sum(20,20);     //40 
  }  
}  

首要示例：

class Animal {    
   public void move(){
      System.out.println("Animals can move");
   }
}

class Dog extends Animal {

   public void move() {
      System.out.println("Dogs can walk and run");
   }
}

public class TestDog {

   public static void main(String args[]) {
      Animal a = new Animal(); // Animal reference and object
      Animal b = new Dog(); // Animal reference but Dog object

      a.move();//output: Animals can move

      b.move();//output:Dogs can walk and run
   }
}