不能：将椭圆和矩形绘制在一起，只能单独绘制

Question

我在这里要做的是生成5个随机的椭圆和矩形。如果我删除

for(MyOval oval : ovals){
                    oval.draw(g);
 }

从第一类开始，它将显示5个随机矩形。如果我删除

for(MyRectangle rectangle : rectangles){       
                rectangle.draw(g);                         
            }  

它将显示5个随机的椭圆。如果我什么都不删除，它就不起作用。我做错了什么？

绘图面板类

import java.awt.Color;
import java.awt.Graphics;
import java.util.Random;
import javax.swing.JPanel;
public class DrawPanel extends JPanel{
    private Random randomNumbers = new Random();
    private MyOval[] ovals;
    private MyRectangle[] rectangles;
    public DrawPanel(){
        setBackground(Color.WHITE);
        ovals = new MyOval[ 5 + randomNumbers.nextInt(5)];
        rectangles = new MyRectangle [ 5 + randomNumbers.nextInt(5)];
        for (int count = 0; count <ovals.length; count++){
            int x1 = randomNumbers.nextInt(300);
            int y1 = randomNumbers.nextInt(300);
            int x2 = randomNumbers.nextInt(300);
            int y2 = randomNumbers.nextInt(300);
            Color color = new Color (randomNumbers.nextInt(256), randomNumbers.nextInt(256), randomNumbers.nextInt(256));
            ovals[count] = new MyOval(x1, y1, x2, y2, color);
            rectangles[count] = new MyRectangle(x1, y1, x2, y2, color);
        }
    }
    public void paintComponent(Graphics g){             
        super.paintComponent(g);                        
        for(MyRectangle rectangle : rectangles){       
            rectangle.draw(g);                         
        }                                              
        for(MyOval oval : ovals){
            oval.draw(g);                              
        }                                                      
    }                                                
}     

主要类别

import javax.swing.JFrame;
public class TestDraw {
    public static void main(String[] args) {
        DrawPanel panel = new DrawPanel();
        JFrame application = new JFrame();
        application.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        application.add(panel);
        application.setSize(300,300);
        application.setVisible(true);
    }
}     

MyOval类

import java.awt.Color;
import java.awt.Graphics;
public class MyOval {
    private int x1;
    private int y1;
    private int x2;
    private int y2;
    private Color myColor;
    public MyOval(int x1, int y1, int x2, int y2, Color color){
        this.x1 = x1;
        this.y1 = y1;
        this.x2 = x2;
        this.y2 = y2;
        myColor = color;
    }
    public void draw(Graphics g){
        g.setColor(myColor);
        g.drawOval(x1, y1, x2, y2);
    }
}

MyRectangle类

import java.awt.Color;
import java.awt.Graphics;
public class MyRectangle {
    private int x1;
    private int y1;
    private int x2;
    private int y2;
    private Color myColor;
    public MyRectangle(int x1, int y1, int x2, int y2, Color color){
        this.x1 = x1;
        this.y1 = y1;
        this.x2 = x2;
        this.y2 = y2;
        myColor = color;
    }
    public void draw(Graphics g){
        g.setColor(myColor);
        g.drawRect(x1, y1, x2, y2);
    }
}

Answer 1

问题是，您分配了两个具有随机长度的数组，但随后使用第一个数组的长度来遍历这两个数组。报价：

ovals = new MyOval[ 5 + randomNumbers.nextInt(5)];
rectangles = new MyRectangle [ 5 + randomNumbers.nextInt(5)];
for (int count = 0; count <ovals.length; count++){
    int x1 = randomNumbers.nextInt(300);
    int y1 = randomNumbers.nextInt(300);
    int x2 = randomNumbers.nextInt(300);
    int y2 = randomNumbers.nextInt(300);
    Color color = new Color (randomNumbers.nextInt(256), randomNumbers.nextInt(256), randomNumbers.nextInt(256));
    ovals[count] = new MyOval(x1, y1, x2, y2, color);
    rectangles[count] = new MyRectangle(x1, y1, x2, y2, color);
}

解决方案是分别初始化每个数组中的元素，直到它们的长度，或者如果您希望两个数组的长度相同，则可以在分配数组之前选择一个随机长度。后期修复如下所示：

int len = 5 + randomNumbers.nextInt(5);
ovals = new MyOval[ len ];
rectangles = new MyRectangle [ len ];

Answer 2

按照Farrukh所说的，我将得到使用相同变量的椭圆和矩形，这意味着它们将在彼此内部。谢谢你的帮助，我找到了另一种方法来解决我的问题，现在它生成了独立的椭圆和矩形

    ovals = new MyOval[ 5 + randomNumbers.nextInt(5)];
    rectangles = new MyRectangle [ 5 + randomNumbers.nextInt(5)];
for (int count = 0; count <ovals.length; count++){
    int x1 = randomNumbers.nextInt(300);
    int y1 = randomNumbers.nextInt(300);
    int x2 = randomNumbers.nextInt(300);
    int y2 = randomNumbers.nextInt(300);
    Color color = new Color (randomNumbers.nextInt(256), randomNumbers.nextInt(256), randomNumbers.nextInt(256));
    ovals[count] = new MyOval(x1, y1, x2, y2, color);           
}
for (int count = 0; count <rectangles.length; count++){
    int x1 = randomNumbers.nextInt(300);
    int y1 = randomNumbers.nextInt(300);
    int x2 = randomNumbers.nextInt(300);
    int y2 = randomNumbers.nextInt(300);
    Color color = new Color (randomNumbers.nextInt(256), randomNumbers.nextInt(256), randomNumbers.nextInt(256));
    rectangles[count] = new MyRectangle(x1, y1, x2, y2, color);
}