java - 理解java方法的问题

Question

也许我在java基础理解方面存在严重差距。在下面的代码中，我无法理解 getLength 方法如何计算步行长度。为什么要在尾部上记忆自己？

class Point {

    private int x;
    private int y;

    public Point(int x, int y) {
        this.x = x;
        this.y = y;
    }

    public static void main(String argv[]) {

        Point p1 = new Point(0, 0);
        // Walk w1 = new Right(new Down(new Left(new Up(new Stop()))));
        Move w2 = new Left(new Left(new Up(new Stop())));
        // Walk w3=new Right(new Stop());
        System.out.println(w2.tail);
    }
}

abstract class Walk {

    public abstract boolean isStop();

    public abstract int getLength();
}

class Stop extends Walk {

    @Override
    public boolean isStop() {
        return true;
    }

    @Override
    public int getLength() {
        return 0;
    }
}

abstract class Move extends Walk {

    Walk tail;


    @Override
    public int getLength() {

        return 1 + tail.getLength();
    }

    Move(Walk tail) {
        this.tail = tail;

    }

    @Override
    public boolean isStop() {
        return true;
    }
}

class Right extends Move {

    public Right(Walk tail) {

        super(tail);

    }
}

class Left extends Move {

    public Left(Walk tail) {
        super(tail);
    }
}

class Up extends Move {

    public Up(Walk tail) {
        super(tail);
    }
}

class Down extends Move {

    public Down(Walk tail) {
        super(tail);
    }
}

Answer 1

您似乎正在创建自己的链接列表，并且 getLength() 方法会迭代整个列表，返回完整的总和。

顺便说一句，请修改此网站的代码格式，尤其是缩进。