使用数组时如何在JPanel上隔开随机圆圈

Question

我正在尝试使用数组在 JPanel 上绘制 7 个随机圆圈。我设法让阵列工作，但现在我无法分隔圆圈。当我运行程序时，我看到绘制了多个圆圈，但它们都在同一个位置。所有的圆圈都有不同的大小和颜色。我遇到的另一个问题是让圆圈向屏幕底部移动。

public class keyExample extends JPanel implements ActionListener, KeyListener{

    private Circle[] circles = new Circle[7];

    Timer t = new Timer(5,this);
    //current x and y
    double x = 150, y = 200;
    double changeX = 0, changeY = 0;

    private int circlex = 0,circley = 0; // makes initial starting point of circles 0
    private javax.swing.Timer timer2;

    public keyExample(){
        t.start();
        addKeyListener(this);
        setFocusable(true);
        setFocusTraversalKeysEnabled(false);
        NewCircle();
        timer2 = new javax.swing.Timer(33,new MoveListener());
        timer2.start();
    }

    public void NewCircle(){
        Random colors = new Random();
        Color color = new Color(colors.nextInt(256),colors.nextInt(256),colors.nextInt(256));

        Random num= new Random();
        int radius = num.nextInt(45);

        for (int i = 0; i < circles.length; i++)
            circles[i] = new Circle(circlex,circley,radius,color);
        }
    }

    public void paintComponent(Graphics g){
        super.paintComponent(g);
        Graphics2D g2 = (Graphics2D) g;
        g2.setColor(Color.BLUE);
        g2.fill(new Rectangle2D.Double(x,y,40,40));
        for (int i = 0; i < circles.length; i++)
            circles[i].fill(g);
    }

    public void actionPerformed(ActionEvent e){
        repaint();
        x += changeX;
        y += changeY;
        changeX = 0;
        changeY = 0;
    }

    public void up() {
        if (y != 0){
            changeY = -3.5;
            changeX = 0;
        }
    }

    public void down() {
        if (y <= 350){
            changeY = 3.5;
            changeX = 0;
        }
    }

    public void left() {
        if (x >= 0) {
            changeX = -3.5;
            changeY = 0;
        }
    }

    public void right() {
        if (x <= 550) {
            changeX = 3.5;
            changeY = 0;
        }
    }

private class MoveListener implements ActionListener{

    public void actionPerformed(ActionEvent e){
        repaint();
        Random speed = new Random();
        int s = speed.nextInt(8);
        }
    }

    public void keyPressed(KeyEvent e){
        int code = e.getKeyCode();
        if (code == KeyEvent.VK_UP){
            up();
        }
        if (code == KeyEvent.VK_DOWN){
            down();
        }
        if (code == KeyEvent.VK_RIGHT){
            right();
        }
        if (code == KeyEvent.VK_LEFT){
            left();
        }
    }

    public void keyTyped(KeyEvent e) { }

    public void keyReleased(KeyEvent e) { }
}



Circle class


import java.awt.*;

public class Circle{

private int centerX, centerY, radius, coord;
private Color color;

public Circle(int x, int y, int r, Color c){
centerX = x;
centerY = y;
radius = r;
color = c;

}

public void draw(Graphics g){
Color oldColor = g.getColor();
g.setColor(color);
g.drawOval(centerX - radius, centerY - radius, radius * 2, radius * 2);
g.setColor(oldColor);

}

public void fill(Graphics g){
Color oldColor = g.getColor();
g.setColor(color);
g.fillOval(centerX - radius, centerY - radius, radius *2, radius * 2);
g.setColor(oldColor);
}

public boolean containsPoint(int x, int y){
int xSquared = (x - centerX) * (x - centerX);
int ySquared = (y - centerY) * (y - centerY);
int RadiusSquared = radius * radius;
return xSquared + ySquared - RadiusSquared <=0;
}



public void move(int xAmount, int yAmount){
centerX = centerX + xAmount;
centerY = centerY + yAmount;

}
}

Answer 1

这是依赖你不理解的借用代码的问题之一......

基本上，您需要做的就是更改圈子的创建，例如...

for (int i = 0; i < circles.length; i++) {
    circles[i] = new Circle(circlex, circley, radius, color);
    circlex += radius;
}

您可能希望重新考虑使用KeyListener，以支持Key Bindings，然后再发现KeyListener 无法按您预期的方式工作...

出于某种奇怪的原因，您从MoveListener 的actionPerfomed 方法中调用NewCirlces，这意味着这些圆圈只是在Timer 的每个触发器上重新创建...而不是, 在构造函数中先调用它

您还在 paintComponent 方法中调用...这应该意味着圆圈永远不会移动，而是随机更改大小...

更新了可运行的示例...

我稍微修改了你的绘画代码NewCircle 和MoveListener...

import java.awt.Color;
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.KeyEvent;
import java.awt.event.KeyListener;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import java.awt.geom.Rectangle2D;
import java.util.Random;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.Timer;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;

public class CircleExample extends JPanel implements ActionListener, KeyListener {

    public static void main(String[] args) {
        EventQueue.invokeLater(new Runnable() {
            @Override
            public void run() {
                try {
                    UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
                } catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
                    ex.printStackTrace();
                }

                JFrame frame = new JFrame("Testing");
                frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
                frame.add(new CircleExample());
                frame.pack();
                frame.setLocationRelativeTo(null);
                frame.setVisible(true);
            }
        });
    }

    private Circle[] circles = new Circle[7];

    Timer t = new Timer(5, this);
    //current x and y
    double x = 150, y = 200;
    double changeX = 0, changeY = 0;

    private int circlex = 0, circley = 0; // makes initial starting point of circles 0
    private javax.swing.Timer timer2;

    public CircleExample() {
        NewCircle();
        t.start();
        addKeyListener(this);
        setFocusable(true);
        setFocusTraversalKeysEnabled(false);
        timer2 = new javax.swing.Timer(33, new MoveListener());
        timer2.start();
    }

    @Override
    public Dimension getPreferredSize() {
        return new Dimension(400, 400);
    }

    public void NewCircle() {
        for (int i = 0; i < circles.length; i++) {
            Random colors = new Random();
            Color color = new Color(colors.nextInt(256), colors.nextInt(256), colors.nextInt(256));

            Random num = new Random();
            int radius = num.nextInt(90);
            circles[i] = new Circle(circlex, circley, radius, color);
            circlex += radius;
        }
    }

    @Override
    public void paintComponent(Graphics g) {
        super.paintComponent(g);
        Graphics2D g2 = (Graphics2D) g;
        g2.setColor(Color.BLUE);
        g2.fill(new Rectangle2D.Double(x, y, 40, 40));
        for (int i = 0; i < circles.length; i++) {
            circles[i].fill(g);
        }
    }

    @Override
    public void actionPerformed(ActionEvent e) {
        repaint();
        x += changeX;
        y += changeY;
        changeX = 0;
        changeY = 0;
    }

    public void up() {
        if (y != 0) {
            changeY = -3.5;
            changeX = 0;
        }
    }

    public void down() {
        if (y <= 350) {
            changeY = 3.5;
            changeX = 0;
        }
    }

    public void left() {
        if (x >= 0) {
            changeX = -3.5;
            changeY = 0;
        }
    }

    public void right() {
        if (x <= 550) {
            changeX = 3.5;
            changeY = 0;

        }
    }

    private class MoveListener implements ActionListener {

        @Override
        public void actionPerformed(ActionEvent e) {
            Random speed = new Random();

            for (Circle circle : circles) {
                int s = speed.nextInt(8);
                circle.move(0, s);
            }
            repaint();
        }
    }

    public void keyPressed(KeyEvent e) {
        int code = e.getKeyCode();
        if (code == KeyEvent.VK_UP) {
            up();
        }
        if (code == KeyEvent.VK_DOWN) {
            down();
        }
        if (code == KeyEvent.VK_RIGHT) {
            right();
        }
        if (code == KeyEvent.VK_LEFT) {
            left();
        }
    }

    public void keyTyped(KeyEvent e) {
    }

    public void keyReleased(KeyEvent e) {
    }

    public class Circle {

        private int centerX, centerY, radius, coord;
        private Color color;

        public Circle(int x, int y, int r, Color c) {
            centerX = x;
            centerY = y;
            radius = r;
            color = c;

        }

        public void draw(Graphics g) {
            Color oldColor = g.getColor();
            g.setColor(color);
            g.drawOval(centerX, centerY, radius, radius);
            g.setColor(oldColor);

        }

        public void fill(Graphics g) {
            Color oldColor = g.getColor();
            g.setColor(color);
            g.fillOval(centerX, centerY, radius, radius);
            g.setColor(oldColor);
        }

        public boolean containsPoint(int x, int y) {
            int xSquared = (x - centerX) * (x - centerX);
            int ySquared = (y - centerY) * (y - centerY);
            int RadiusSquared = radius * radius;
            return xSquared + ySquared - RadiusSquared <= 0;
        }

        public void move(int xAmount, int yAmount) {
            centerX = centerX + xAmount;
            centerY = centerY + yAmount;

        }

    }
}