JAVA，setter 没有将发送到我的构造函数程序的值返回零

Question

我遇到的错误是控制台在应该显示类似于以下内容的情况下打印出点值中的全零 (1,2) (3,4) (5,6) (7,8)

我追踪到了 setter 的错误，它没有加载到值中。 示例

 public void setPoint1(double newX, double newY) {
  this.N1x = newX;
  this.N1y = newY;

}

这不会将私有(private) double N1.x 更新为相应的构造函数值 1。我相信这是问题所在，但我是编码新手，仍然有很多东西需要学习。

据我了解，对构造函数中 setter 的调用应该从构造函数调用中获取 1 到 8 的值，然后发送到 setter，然后将它们分配给私有(private) double ，然后执行 Point Class 操作，这些值被保存到 point1 到 point4 对象中，然后从返回其存储值的 main 方法调用该对象。

下面是我关于我的问题的代码。先感谢您!

public class Quadrilateral {

   //Receives data from constructor 
   //initializes the variables for point objects  
   private double N1x; private double N1y;
   private double N2x; private double N2y;
   private double N3x; private double N3y;
   private double N4x; private double N4y;

   //creates new point objects
   Point point1 = new Point(N1x,N1y);
   Point point2 = new Point(N2x,N2y);
   Point point3 = new Point(N3x,N3y);
   Point point4 = new Point(N4x,N4y);

   // Encapsulation for point 1
   public Point getPoint1() {
      return point1;
   }
   public void setPoint1(double newX, double newY) {
      this.N1x = newX;
      this.N1y = newY;
   }

   // Encapsulation for point 2
   public Point getPoint2() {
      return point2;
   }
   public void setPoint2(double newX, double newY) {
      this.N2x = newX;
      this.N2y = newY;
   }

   // Encapsulation for point 3
   public Point getPoint3() {
      return point3;
   }
   public void setPoint3(double newX, double newY) {
      this.N3x = newX;
      this.N3y = newY;
   }

   // Encapsulation for point 4
   public Point getPoint4() {
      return point4;
   }
   public void setPoint4(double newX, double newY) {
      this.N4x = newX;
      this.N4y = newY;
   }

   //constructor for Quadrilateral
   //takes in 4 sets of point values
   Quadrilateral(
         double N1x, double N1y,
         double N2x, double N2y,
         double N3x, double N3y,
         double N4x, double N4y){

      setPoint1(N1x, N1y);
      setPoint2(N2x, N2y);
      setPoint3(N3x, N3y);
      setPoint4(N4x, N4y);

   }

   // gets the (x,y) values 
   //remember to override to add additional values and change shape

   public String toString() {
      return "Quadrilateral "+"\n"+ 
            "Node points are "+"\n"+
            getPoint1()+"\n"+
            getPoint2()+"\n"+
            getPoint3()+"\n"+
            getPoint4();
   }

public static void main(String[] args) {

   Quadrilateral quadrilateral = new Quadrilateral(1,2,3,4,5,6,7,8);
   System.out.println(quadrilateral.toString());
   }

}

这是点类

public class Point {
   private double x;
   private double y;

   public double getX() {
      return x;
   }
   public double getY() {
      return y;
   }
   public void setX(double newX) {
      this.x = newX;
   }
   public void setY(double newY) {
      this.y= newY;
   }
   Point(double x, double y){//when this constructor is called it performs encapsulation 
      setX(x);
      setY(y);
   }
   public String toString() {
      return "("+getX()+","+getY()+")";
   }
}

Answer 1

如果我正确理解你的问题，你应该这样做:

//creates new point objects
Point point1;
Point point2;
Point point3;
Point point4;

还有这个:

public void setPoint1(double newX, double newY) {
    this.N1x = newX;
    this.N1y = newY;
    point1 = new Point(newX, newY);
}

(其他点设置者也是如此)

在您的代码中，您仅在坐标为空时初始化了点，然后才在 setPoint 方法中首次设置坐标