java为什么我所有的形状都卡在我的JPanel的左上角？

Question

我已经创建了一个JPanel，其中充满了圆、线和矩形，它们应该在JPanel周围随机生成，但是圆和矩形只显示在JPanel的左上角，而不是在整个JPanel中随机出现，而线工作得很好。我想知道是否有人能帮我

import java.awt.Color;
import java.awt.Graphics;
import java.util.Random;
import javax.swing.JPanel;

/**
 *
 * 
 */
public class RandomShapesPanel extends JPanel
{
    private Color rColor;
    private Random rGen;
    private Random num;

    @Override
    protected void paintComponent(Graphics g)
    {
    super.paintComponent(g);
    int x = this.getWidth();
    int y = getHeight();
    int x1, y1, x2, y2;
    rGen = new Random();
    num = new Random();
    for(int i = 1; i <= 35; i++)
    {
        rColor = new Color(rGen.nextInt(256),rGen.nextInt(256),
                rGen.nextInt(256));
        g.setColor(rColor);
        x1 = rGen.nextInt(x - 1) + 1;
        x2 = rGen.nextInt(x - 1) + 1;
        y1 = rGen.nextInt(y - 1) + 1;
        y2 = rGen.nextInt(y - 1) + 1;
        g.drawLine(x1, y1, x2, y2);
    }
    for(int i = 1; i <= 35; i++)
    {
        rColor = new Color(rGen.nextInt(256),rGen.nextInt(256),
                rGen.nextInt(256));
        g.setColor(rColor);
        x1 = num.nextInt(50) + 10;
        x2 = num.nextInt(50) + 10;
        y1 = num.nextInt(50) + 10;
        y2 = num.nextInt(50) + 10;
        g.drawRect(x1, y1, x2, y2);
    }
    for(int i = 1; i <= 35; i++)
    {
        rColor = new Color(rGen.nextInt(256),rGen.nextInt(256),
                rGen.nextInt(256));
        g.setColor(rColor);
        x1 = num.nextInt(50) + 10;
        x2 = num.nextInt(50) + 10;
        y1 = num.nextInt(50) + 10;
        y2 = num.nextInt(50) + 10;
        g.fillRect(x1, y1, x2, y2);
    }
    for(int i = 1; i <= 35; i++)
    {
        rColor = new Color(rGen.nextInt(256),rGen.nextInt(256),
                rGen.nextInt(256));
        g.setColor(rColor);
        x1 = num.nextInt(50) + 10;
        x2 = num.nextInt(50) + 10;
        y1 = num.nextInt(50) + 10;
        y2 = num.nextInt(50) + 10;
        g.drawOval(x1, y1, x2, y2);
    }
    for(int i = 1; i <= 35; i++)
    {
        rColor = new Color(rGen.nextInt(256),rGen.nextInt(256),
                rGen.nextInt(256));
        g.setColor(rColor);
        x1 = num.nextInt(50) + 10;
        x2 = num.nextInt(50) + 10;
        y1 = num.nextInt(50) + 10;
        y2 = num.nextInt(50) + 10;
        g.fillOval(x1, y1, x2, y2);
    }
    }
}

Answer 1

您必须这样定义这些：

for(int i = 1; i <= 35; i++)
{
    rColor = new Color(rGen.nextInt(256),rGen.nextInt(256),
            rGen.nextInt(256));
    g.setColor(rColor);
    x1 = num.nextInt(x-50) + 10;
    x2 = num.nextInt(50) + 10;
    y1 = num.nextInt(y-50) + 10;
    y2 = num.nextInt(50) + 10;
    g.drawRect(x1, y1, x2, y2);
}