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如何使一个圆在旋转一次后停止或在一个循环后停止

actionlistener jbutton jframe timer java

Johann Chu · 技术社区 · 2 年前

这就是我现在拥有的。在我点击按钮后,它应该会从中心向右然后向左反弹,然后回到原来的位置。然后我应该能够再次点击按钮,这样它就会开始另一个循环。

public class Bounce extends JFrame {

private static JButton btnMovement = new JButton("Click");
private Container container;
private Timer timer;
private int x = 290;
private int y = 350;
private int radius = 100;
private int moves = 2;

public Bounce() {
    container = getContentPane();
    container.setLayout(new FlowLayout());
    final MoveListener ml = new MoveListener();
    btnMovement.addActionListener(ml);
    timer = new Timer(5, ml);
}

private void Move() {
    x += moves;
    
    if (x + (radius * 2) > getWidth()) {
        x = getWidth() - (radius * 2);
        moves *= -1;
    } else if (x < 0) {
        x = 0;
        moves *= -1;
    }
    repaint();
}
    
class MoveListener implements ActionListener {
    public void actionPerformed(final ActionEvent event) {
        if (!timer.isRunning()){
            timer.start();
        } else if (timer.isRunning() && x == 290 && y == 350){ // I don't know what condition to put
            timer.stop(); 
        }
        Move();
    }
}

public void paint (Graphics g){
    super.paint(g);
    g.setColor(Color.black);
    g.fillOval(x - 5, y - radius - 5, radius + 110, radius + 110);
    g.setColor(Color.red);
    g.fillOval(x, y - radius, radius * 2, radius * 2);
}

public static void main(String args[]){
    final JFrame window = new Bounce();
    window.add(btnMovement);
    window.setSize(800, 800);
    window.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    window.setVisible(true);
}

}

1 回复 | 直到 2 年前

MadProgrammer 2 年前

这个 ActionListener 对于 Timer 应该是分开的——它充当伪循环。基本上,一旦球从左侧反弹,你可以改变一个标志,表明它到达或通过中点时应该停止,例如。。。

import java.awt.BorderLayout;
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 javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.Timer;

public class Main {
    public static void main(String[] args) {
        new Main();
    }

    public Main() {
        EventQueue.invokeLater(new Runnable() {
            @Override
            public void run() {
                JFrame frame = new JFrame();
                frame.add(new TestPane());
                frame.pack();
                frame.setLocationRelativeTo(null);
                frame.setVisible(true);
            }
        });
    }

    public class TestPane extends JPanel {

        private Timer timer;

        private int xPos;
        private int yPos;

        public TestPane() {
            JButton btn = new JButton("Start");

            xPos = 95;
            yPos = 95;

            timer = new Timer(5, new ActionListener() {
                private int xDelta = 1;
                private boolean hasBounced = false;
                @Override
                public void actionPerformed(ActionEvent e) {
                    xPos += xDelta;
                    int middleX = (getWidth() / 2) - 5;
                    if (xPos + 10 > getWidth()) {
                        xPos = getWidth() - 10;
                        xDelta *= -1;
                    } else if (xPos < 0) {
                        xPos = 0;
                        xDelta *= -1;
                        hasBounced = true;
                    } else if (hasBounced && xPos >= middleX) {
                        timer.stop();
                        btn.setEnabled(true);
                        hasBounced = false;
                    }
                    repaint();
                }
            });

            setLayout(new BorderLayout());
            btn.addActionListener(new ActionListener() {
                @Override
                public void actionPerformed(ActionEvent e) {
                    btn.setEnabled(false);
                    timer.start();
                }
            });

            add(btn, BorderLayout.SOUTH);
        }

        @Override
        public Dimension getPreferredSize() {
            return new Dimension(200, 200);
        }

        @Override
        protected void paintComponent(Graphics g) {
            super.paintComponent(g);
            Graphics2D g2d = (Graphics2D) g.create();
            g2d.drawOval(xPos, yPos, 10, 10);
            g2d.dispose();
        }        
    }
}

一个更复杂的解决方案是在计时器启动时记录当前位置,并将其用作“终点”,但我将留给您决定