java - 要点列表+构造函数和方法问题

Question

因此，对于这个项目，我希望输入一个包含多个点的数组。 (没有具体数字)。我对如何处理方法和构造函数感到困惑，因为某些方法需要更改，例如获取 X 或 Y 值的平均值。我是否以正确的方式处理这个项目？我应该使用点列表的克隆，还是数组列表或什么...(注意我仅显示 PolygonImpl 类的一部分作为示例，它们的功能都类似)类点包含:

public class Point {

private double x;
private double y;

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

public double getX() {
    return x;
}

public double getY() {
    return y;
}

public Point translate(double dx, double dy) {
    return new Point(x+dx, y+dy);
}

public double distanceTo(Point p) {
    return Math.sqrt((p.x - x)*(p.x -x) + (p.y-y)*(p.y-y));
}

}

public class PolygonImpl implements Polygon {

private double xSum=0;
private double ySum=0;
private ArrayList<Point> points;
private Point[] pList;
private Point a;

PolygonImpl(Point[] pList) {

    this.pList = pList.clone();
    points = new ArrayList<Point>();

    for (int index = 0; index < pList.length; index++) {
           points.add(pList[index]);
       xSum += pList[index].getX();
       ySum += pList[index].getY();


    }
}



public Point getVertexAverage() {
     double xSum = 0;
     ArrayList<Point> vlist = new ArrayList<Point> ();
     double ySum = 0;
    for (int index = 0; index < vlist.size(); index++) {
         xSum = xSum + vlist.get(index).getX();
         ySum = ySum + vlist.get(index).getY();
        }

    return new Point(xSum/getNumSides(), ySum/getNumSides());
}

public int getNumSides() {
    return pList.length;
}

public void move(Point c) {
    Point newCentroid = new Point(a.getX()+ c.getX(), a.getY() +c.getY());


}

public void scale(double factor) {

 ArrayList<Point> points = new ArrayList<Point> ();

    for (int index = 0; index < pList.length; index++) {
        { double x = pList[index].getX() *factor;
          double y = pList[index].getY() * factor;
          Point a = new Point(x,y);
            points.add(index,a);

        }
    }
     }

Answer 1

在这种情况下，我认为您不需要额外的 List 对象；它们是多余的。 这是仅使用 pList 数组的代码。

public class PolygonImpl implements Polygon {

private double xSum=0;
private double ySum=0;
private Point[] pList;
private Point a;

    PolygonImpl(Point[] pList) {

        this.pList = pList.clone();

        for (int index = 0; index < pList.length; index++) {
           xSum += pList[index].getX();
           ySum += pList[index].getY();
        }
    }



    public Point getVertexAverage() {
         double xSum = 0;
         double ySum = 0;
        for (int index = 0; index < pList.length; index++) {
             xSum = xSum + pList[index].getX();
             ySum = ySum + pList[index].getY();
            }

        return new Point(xSum/getNumSides(), ySum/getNumSides());
    }

    public int getNumSides() {
        return pList.length;
    }

    public void move(Point c) {
        Point newCentroid = new Point(a.getX()+ c.getX(), a.getY() +c.getY());


    }

    public void scale(double factor) {
        for (int index = 0; index < pList.length; index++)
        {
            double x = pList[index].getX() *factor;
            double y = pList[index].getY() * factor;
            Point a = new Point(x,y);
            pList[index] = a;

        }
    }