; 다형성

class polytest

{
 public static void main(String[] args)
 {
  System.out.println("Hello World!");
  osk sk=new osk2();
  sk.os();
 }
}

class osk
{
 void os(){
  System.out.println("사각형");
 }
};

class osk2 extends osk
{
 void os(){
 System.out.println("삼각형");
 }
};

출력은
Hello World!
삼각형