Java - 了解私有(private)最终自定义类型的返回类型

Question

我试图理解下面的代码，其中返回类型被视为不兼容。

 return new PassLine(One, Two, roll);
 incompatible types: PassLine cannot be converted to TheDie

希望有人能给我一些启发，以便我可以继续。

我希望得到 dieOne + dieTwo 的掷骰总和。

public class PassLine {
    private int thePoint;

    private final TheDie dieOne;
    private final TheDie dieTwo;
    private final TheDie rollTheDie;

    public PassLine(TheDie dieOne, TheDie dieTwo, TheDie rollTheDie) {
        super();
        this.dieOne = dieOne;
        this.dieTwo = dieTwo;
        this.rollTheDie = rollTheDie;
    }

    public TheDie dieOne() {
        TheDie obj = new TheDie();
        obj.rollTheDie();
        return dieOne;
    }

    public TheDie dieTwo() {
        TheDie obj = new TheDie();
        obj.rollTheDie();
        return dieTwo;
    }

    public TheDie rollTheDie() {
        dieOne();
        dieTwo();
        return rollTheDie;
    }

        public PassLine passLine() {

    TheDie One = dieOne();
    TheDie Two = dieTwo();
    TheDie roll = rollTheDie();

    return new PassLine(One, Two, roll);
}

    public static void main(String[] args) {
        System.exit(0);
    }
}

来自 - 公开期末类 TheDie

    public int rollTheDie() {

    Random rand = new Random();
    oneDie = rand.nextInt(6) + 1;

    return oneDie;

    }

新的错误信息如下:

在: return new PassLine(one, two, roll);

错误:

     Incompatible Type: TheDiecannot be converted to String
     Incompatible Type: TheDiecannot be converted to String
     Introduce...
     May split declaration into a declaration and assignment 
     Flip operands of the binary operator

Answer 1

这个错误再清楚不过了，

public TheDie PassLine() {

    TheDie One = dieOne();
    TheDie Two = dieTwo();
    TheDie roll = rollTheDie();

    return new PassLine(One, Two, roll);
}

您指定该方法应返回一个 TheDie 对象，同时返回一个 PassLine 对象。

根据你的错误信息

incompatible types: PassLine cannot be converted to TheDie

两种类型不兼容，将您的方法更改为

public PassLine PassLine() {

    TheDie One = dieOne();
    TheDie Two = dieTwo();
    TheDie roll = rollTheDie();

    return new PassLine(One, Two, roll);
}

也许您真的想通过调用一个在新的 PassLine 对象上真正返回 TheDie 的方法来返回一个 TheDie。