多态定义榨汁机 JuiceMachine 有榨汁方法 makeJuice传入相应的水果如果传入的是 Apple 输出 流出苹果汁传入的是Orange 输出流出橙汁传入的是 Banana 输出流出香蕉酱

public class JuiceMachine { public void makeJuice(Fruit fruit) { if (fruit instanceof Apple) { System.out.println("流出苹果汁"); } else if (fruit instanceof Orange) { System.out.println("流出橙汁"); } else if (fruit instanceof Banana) { System.out.println("流出香蕉酱"); } } }

public class Fruit {}

public class Apple extends Fruit {}

public class Orange extends Fruit {}

public class Banana extends Fruit {}