尝试使用 get/set 方法 [关闭]

Question

看看 Circle 类。每次 if 语句评估为 true 时，我都希望计数器加一。我正在尝试使用 set 方法来为我完成这项工作，但是当我在 main 方法中检查 counter 的值时，它并没有计数。有小费吗？

package circle;

import java.awt.Color;
import java.awt.Graphics; 
import java.awt.Graphics2D;
import java.awt.geom.Ellipse2D;
import java.awt.geom.Rectangle2D;
import javax.swing.JApplet;


public class Shapes extends JApplet {

private int squareLength = 0;
private int count = 0;
private double areaSquares = 0;
private double areaCircle = 0;

public void setPixelDimOfSquare(int width) {squareLength = width;}

public void setCount(int n) {count = n++;}

public int getCount() {return count;}

@Override
public void paint(Graphics g) {

    Graphics2D g2 = (Graphics2D) g;

    //shapes
    //adds sphere (xcoord,ycoord,width of framing rect, height of framing rect)
    g2.draw(new Ellipse2D.Double(0, 0, 1000, 1000));

    //builds square grid and counts number of whole squares in the circle.
    for (int i = 0; squareLength*i <= 1000; i++){
        for (int j = 0; squareLength*j <= 1000; j++) {

         if(new Ellipse2D.Double(0,0,1000,1000).contains(new Rectangle2D.Double(squareLength*i,squareLength*j,squareLength,squareLength))){
             setCount(1);
             g2.setColor(Color.black);
             g2.fillRect(squareLength*i,squareLength*j,squareLength,squareLength);
         } else {
             g2.drawRect(squareLength*i,squareLength*j,squareLength,squareLength);
         }
        }
    } 
    System.out.println("Shape: There are " + getCount() + " squares in the circle.");
} 

public double areaSquares() {
    areaSquares = Math.pow(squareLength,2) * count;
    return areaSquares;
}

public double areaCircle() {

    areaCircle = Math.PI * Math.pow(1000, 2);
    return areaCircle;


}
}

现在是主要的

package circle;

import java.util.Scanner;
import javax.swing.JApplet;
import javax.swing.JFrame;
import javax.swing.WindowConstants;

public class Main {

public static void main(String[] args) {

    //Gets the desired number of boxes
    //Scanner sc = new Scanner(System.in);
    //System.out.print("Please enter number of boxes:");
    //double boxes = sc.nextDouble();

    // Builds frame for shapes.
    Shapes shape = new Shapes();
    shape.setPixelDimOfSquare(10);

    JFrame frame = new JFrame("Draw Shapes Demo");
    frame.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);

    frame.getContentPane().add(shape);
    frame.pack();
    frame.setSize(1000,1000);
    frame.setVisible(true);


    System.out.println("Main: There are " + shape.getCount() + " squares in the circle.");
}
}

Answer 1

将你的 setCount 修改为：

public void setCount(){
  count++;
}

Answer 2

这一行是你的问题：

public void setCount(int n) {count = n++;}

当你说count = n++;时，就相当于

count = n;
n = n + 1;

因为n++ 是后自增运算符。 这可能不是您想要的行为。如果你把

public void setCount(int n) {count+= n;}

每次调用该方法时，它都会将count 增加n。 += 运算符只是 count = count + n 的简写

---

此外，将方法命名为setCount 会有点误导，如果它实际上将计数增加了给定的数字。这意味着它将设置count = n 而不是count = count + n。我建议将其重命名为 incrementCount。

就个人而言，对于这么简单的事情，我什至不会为 getter 和 setter 烦恼。只需在 for 循环之前定义一个 int count 并使用 count++ 在每次 if 语句评估为 true 时递增它

Answer 3

尝试将您的 setCount 方法更改为：

    public void setCount() {count++;}

每次在 paint 方法中调用时，您的代码都会将 count 设置为 2。