为什么这个返回方法不会编译? [英] Why Won't This Return Method Compile?

问题描述

我正在尝试制作一个简单的程序，您可以通过输入命令在四个方向上移动一个空格.这是我的代码:

I am trying to make a simple program where you can move one space in four directions by typing in commands. Here is my code:

public class Map {
    public int x;
    public int y;
}

和

import java.util.Scanner;

public class Mover {
    Scanner input = new Scanner(System.in);
    Map map = new Map();

    public int move(int x, int y){
        map.x = x;
        map.y = y;
        String direction = input.next();

        System.out.println("Where will you move?");

        if(direction.equalsIgnoreCase("move right")){
            x++;
            return x;
        }

        if(direction.equalsIgnoreCase("move left")){
            x--;
            return x;
        }

        if(direction.equalsIgnoreCase("move up")){
            y++;
            return y;
        }

        if(direction.equalsIgnoreCase("move down")){
            y--;
            return y;
        }
    }
    public static void main(String args[]){
        Mover mover = new Mover();
    }
}

编译器说问题是我需要返回一个 int 值，但很明显我在我所做的每个 if 语句中都有.具体来说，它说在方法的最后返回一个y"值将解决问题.尝试此操作后，错误消失.但是当编译时，程序立即终止.我做错了什么?

The compiler says the problem is that I need to return an int value, but clearly I have in within every if statement I've made. Specifically, it says returning a 'y' value at the very end of the method will solve the problem. After trying this, the errors go away. But when compiled, the program instantly terminates. What am I doing wrong?

推荐答案

如果您的所有条件都为假，则您的方法的执行将到达您的方法的末尾，而不会遇到 return 语句.您必须为这种情况提供返回值.

If all your conditions are false, execution of your method will reach the end of your method without hitting a return statement. You must provide a return value for that situation.

添加最后一行来完善您的方法:

Add a final line to hone body of your method:

return 0; // for example

Java 方法没有默认"返回值.

Java methods do not have "default" return values.

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