在使用多态性的方法中调用方法？

Question

我需要使用多态性在play()方法中调用move()方法。我不知道该怎么做。我的程序中的其他一切都能正常工作，我唯一的问题是如何在play()方法中使用move()方法。Move()方法在另一个名为“Human”的类中，这个类也使用"player“接口。该方法可以正常工作。

public interface Players {
    int move();   // returns an int that is given by user    
}
// Method that I need call the move() method in
// You may ignore the rest of the code expect where I commented 
class Nim implements Players {
    private int marbles = 0;
    private int take = 0;
    public void play() {
        playerName = obj2.getName();
        System.out.println("Player " + playerName);
        turn();
        getComp();
        int removeMarbles = 0;
        System.out.println("\nNumber of marbles: " + marbles);
        Pile obj = new Pile();
        while (marbles > 0) {
            if (turn % 2 != 0) {
                take = move() // need to call move method using polymorphism, ***code does not work just to show where I need help
                System.out.println(playerName + " took " + take + " marble(s)");
                marbles = marbles - take;
                System.out.println("There are " + marbles + " marbles left.");
            }

            if (turn % 2 == 0) {
                if (compName.equals("Dumb")) {
                    removeMarbles = (int)(Math.random() * (marbles / 2) + 1);
                    System.out.println("\nThe computer took " + removeMarbles + " marble(s)");
                    marbles -= removeMarbles;
                }

                if (compName.equals("Smart")) {
                    int pile = marbles;
                    int power = 2;
                    if (marbles <= power) {
                        removeMarbles = 1;
                    }
                    if (marbles > power) {
                        while (power < marbles) {
                            power = power * 2;
                        }
                        removeMarbles = ((power / 2) - 1);
                    }
                    marbles = removeMarbles;
                    System.out.println("\nThe computer took " + (pile - removeMarbles) + " marble(s)");
                }
                System.out.println("There are " + marbles + " marbles left.\n");
            }

            if (marbles == 0) {
                if (turn % 2 != 0) {
                    System.out.println("\nThe computer is the winner!!!!");
                } else {
                    System.out.println("\n" + playerName + " is the winner!!!!");
                }
            }
            turn++;
        }
    }
}

Answer 1

Interfaces are contracts describing the group of related methods with empty bodies.您需要在子类中实现move()方法，然后使用任何其他功能覆盖该方法：

public int move(){

  // Implements interface .move();
   System.out.println("Nim .move()");
}

从Docs

如果要在播放器中实现该方法，则不能将其作为接口实现，因为该行为将被实现该接口的方法覆盖。相反，您应该考虑使用super关键字的抽象类结构：

从Docs

Answer 2

首先，您需要在Human类中实现该方法，如下所示

public class Humans implements Players {
   public int move(){
       // your logic here
   }
}

然后，您可以使用object调用该方法，如下所示

Players  ob = new Humans();
take = ob.move();

Answer 3

目前，您的move()被声明为一个变量。你会想让它成为接口中的一个方法，这样你就不需要强制转换就可以调用它。

基本上，

int move();

应该看起来像这样：

public int move(){
  // your code here;
}