java - 如何对类型为 "NameOfClass"的数组进行排序

Question

我有一个程序可以找到一对点之间的最大距离:这是类点:

public class Point {

  private int x;
  private  int y;
  public Point (int a, int b) {
      x=a; y=b;
  }
  public double distance (Point p){
    int tempx , tempy;
    tempx=(x-p.x)*(x-p.x);
    tempy=(y-p.y)*(y-p.y);
    return  Math.sqrt(tempx+tempy);
  }
  public void show(){
      System.out.println("(" + x + "," + y + ")");
  }
}

这是主程序:

public static void main(String[] args) {
    // TODO Auto-generated method stub
    Point[] allPoints=new Point[5];
      int k=0;
      int rx,ry;
      while (k<=allPoints.length-1){             
      rx=(int)(1+Math.random()*10);               
      ry=(int)(1+Math.random()*10);
      allPoints[k]=new Point(rx, ry);
      k++;
      }

      int i,j,mi,mj;
      double mDis=0,cDis;
      mi=mj=0;
      i=0;
      while ( i<allPoints.length-1) {
        j=i+1;
        while (j<allPoints.length) {
          cDis= allPoints[i].distance(allPoints[j]);
          if (cDis>mDis){
          mDis=cDis; 
          mj=j; 
          mi=i;}
          j++;
         }    
         i++;
        }

      allPoints[mj].show();
      allPoints[mi].show();
        System.out.print("max dis is " + mDis +" first point: " + mi + " second point: " + mj);
} 
      //////////


}

正如您所看到的，程序有一个包含 5 个“单元格”的数组，并且它找到了最大距离的对，我想知道如何更改程序，以便它根据距离对点进行排序和打印它们之间。例如: 点 1:2,2 点 2:6,6 点 3:1,1所以Point3和Point 1之间的距离最小所以程序应该输出:1,1 2,2 6,66,6 之所以排在最后，是因为 6,6 和 2,2 之间的距离最大，我是 Java 新手，所以如果您能向我解释一下，这将是一个很大的帮助。

Answer 1

创建一个消耗一对点的新 Line 对象。将所有点组合放入​​线列表中，并根据这些线的长度(点之间的距离)对该列表进行排序。

public static void main(String[] args) {
    ...
    List<Line> lines = new ArrayList<>();
    while (i < allPoints.length - 1) {
        ...
        while (j < allPoints.length) {
            lines.add(new Line(allPoints[i], allPoints[j]));
            ...
        }
        ...
    }
    ...
    Collections.sort(lines, Comparator.comparingDouble(Line::getLength));
    System.out.println("Lines: ");
    for (Line line : lines) {
        System.out.println(line);
    }
}

class Point {
    private int x;
    private  int y;

    public Point (int a, int b) {
        x=a; y=b;
    }

    public double distance (Point p){
        int tempx , tempy;
        tempx=(x-p.x)*(x-p.x);
        tempy=(y-p.y)*(y-p.y);
        return  Math.sqrt(tempx+tempy);
    }

    public void show(){
        System.out.println(this);
    }

    @Override
    public String toString() {
        return "(" + x + "," + y + ")";
    }
}

class Line {
    private final Point a;
    private final Point b;
    private double length;

    public Line(Point a, Point b) {
        this.a = a;
        this.b = b;
        this.length = a.distance(b);
    }

    public double getLength() {
        return length;
    }

    @Override
    public String toString() {
        return "Line{" +
                "a=" + a +
                ", b=" + b +
                ", length=" + length +
                '}';
    }
}