Question

所以我试图在类中编写一个使用Point和Line的代码。它的目的是创建一个有两个点的线，然后找到该线的斜率。这就是代码的样子

public class LineMain{
   public static void main (String[]args){
   Point p1=new Point(22,3);
   Point p2=new Point(4,7);
   Line Line1=new Line(p1,p2);
   System.out.println(Line1.getSlope());
   }
}

public class Line{
   private Point p1;
   private Point p2;

   public Line(Point p1, Point p2){
      this.p1=p1;
      this.p2=p2;
   }

   public Point getP1(){
      return p1;
   }

   public Point getP2(){
      return p2;
   }    
   public double getSlope(){
        int slope;
        slope = ((p2.y-p1.y)/(p2.x-p1.x));
        return slope;
   }
}

public class Point{
   private int x;
   private int y;
   /*
   public Point(){
      this(0,0);
   }
   */
   public Point(){
      x=0;
      y=0;
   }

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

   public Point(Point p){
      x=p.x;
      y=p.y;
   }

   /*
   public Point (int x1,int y1){
      x=x1;
      y=y1;
   }   
   */
   public int getX(){
      return x;
   }

   public int getY(){
      return y;
   }

   public void setX(int x){
      this.x=x;
   }

   public void setY(int y){
      this.y=y;
   }            

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

   public double distance(Point other){
      double x1=other.x;
      double y1=other.y;
      double z=Math.pow((x1-x),2)+Math.pow((y1-y),2);
      return z;
   }

   public double slope(Point other){
      double x1=other.x;
      double y1=other.y;
      if (x1==x){
         throw new IllegalArgumentException("no");
      }else{   
         double z=(y1-y)/(x1-x);
         return z;
         }
      }
}

但每次我尝试运行代码时都会弹出错误：

Line.java:24: error: y has private access in Point
        slope = ((p2.y-p1.y)/(p2.x-p1.x));
                    ^
Line.java:24: error: y has private access in Point
        slope = ((p2.y-p1.y)/(p2.x-p1.x));
                         ^
Line.java:24: error: x has private access in Point
        slope = ((p2.y-p1.y)/(p2.x-p1.x));
                                ^
Line.java:24: error: x has private access in Point
        slope = ((p2.y-p1.y)/(p2.x-p1.x));
                                     ^
4 errors

请帮忙！

Answer 1

你有两个选择，虽然我真的希望你选择后者。

将Point字段设为公开。这将允许您使用它们，因为您目前以违反惯例为代价。
```
public class Point {
    public double x, y; // Possible
    // constructor detail
}
```

为getX()的字段创建getY()和Point，并将其保留为private。但是，您必须重写x和y的使用，但代价是保留惯例。

public class Point {
    private double x, y;
    // constructor detail

    public double getX() {
        return x;
    }

    public double getY() {
        return y;
    }
}

Answer 2

您需要将方法getX()和getY()添加到Point课程，然后在Line课程中使用它们。

私人访问导致的错误

2 个答案: