java - 我的大脑卡住了，帮我使这个方法有效 :>

Question

我有以下代码，我可以看出值之间存在联系。但是，我无法集中精力并弄清楚如何使用一些 add subtract modelo haxx 删除 switch 语句。真的很想得到一些帮助，让这个方法更顺利。

标题变量是 0、1、2 或 3。

public static int getRotation(Point currentPoint, Point nextPoint, int heading) {
    int rotation = -1;
    if(currentPoint.getX() < nextPoint.getX()) /* DRIVE WEST */  {
        switch(heading) {
            case 0: rotation = 1; break;
            case 1: rotation = 0; break;
            case 2: rotation = 3; break;
            case 3: rotation = 2; break;
        }
    } else if(currentPoint.getX() > nextPoint.getX()) /* DRIVE EAST */ {
        switch(heading) {
            case 0: rotation = 3; break;
            case 1: rotation = 2; break;
            case 2: rotation = 1; break;
            case 3: rotation = 0; break;
        }
    } else if(currentPoint.getY() < nextPoint.getY()) /* DRIVE  NORTH */ {
        switch(heading) {
            case 0: rotation = 0; break;
            case 1: rotation = 3; break;
            case 2: rotation = 2; break;
            case 3: rotation = 1; break;
        }
    }  else if(currentPoint.getY() > nextPoint.getY()) /* DRIVE SOUTH */ {
        switch(heading) {
            case 0: rotation = 2; break;
            case 1: rotation = 1; break;
            case 2: rotation = 0; break;
            case 3: rotation = 3; break;
        }
    }

    return rotation;
}

编辑:我确实忘记提到 nextPoint 与 currentPoint 相比只能是 +-x 或 y。如果 currentPoint 是 (0,0)，newPoint 必须是 (-1,0)、(1,0)、(0,-1) 或 (0,1)。

Answer 1

你可以试试。

int eastWest = Double.compare(currentPoint.getX(), nextPoint.getX()) 
if (eastWest == 0) {
    int northSouth = Double.compare(currentPoint.getX() , nextPoint.getX()) 
    /* DRIVE NORTH (-1), SOUTH (+1) */ 
    if (northSouth == 0)
       rotation = -1;
    else
       rotation = (5 + northSouth - heading) % 4;
} else {
    /* DRIVE WEST (-1), EAST (+1) */  
    rotation = heading ^ (2 + eastWest);
}

注意:我希望看到这些函数的一些对称性，因为每个方向似乎都有不同的组合并且听起来不对。