如何在 Java 中聆听按键时使图像移动.

问题描述：

我开始学习 Java 编程，我认为通过游戏开发学习 Java 很酷.我知道如何绘制图像并聆听按键然后移动该图像.但是是否可以在窗口监听按键时使图像来回移动到窗口?例如，当图像或物体(如宇宙飞船)在窗口中从左到右移动时，如果我按空格键，激光将在屏幕底部发射(很酷吧:D).但基本上我只想知道如何在窗口监听按键时使图像从左向右移动.

I'm starting to learn java programming and I think it's cool to learn java through game development. I know how to draw image and listen to a keypress then move that image. But is it possible to make the image move back and forth to the window while the window is listening to a keypress? Like for example, while the image or object(like spaceship) is moving left to right in the window, then if I press space key, a laser will fire at the bottom of the screen( cool huh :D ). But basically I just want to know how to make the image move left to right while the window is listening to a keypress.

我想我会在我的窗口中添加一个键侦听器，然后触发一个无限循环来移动图像.或者我需要学习线程以便另一个线程移动对象吗?

I'm thinking that I will add a key listener to my window then fire an infinite loop to move the image. Or do I need to learn about threading so that another thread will move the object?

请指教.

非常感谢.

答

但基本上我只想知道如何在窗口监听按键时使图像从左向右移动

But basically I just want to know how to make the image move left to right while the window is listening to a keypress

您可以使用 Swing Timer 为图像设置动画:

You can use a Swing Timer to animate an image:

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;

public class TimerAnimation extends JLabel implements ActionListener
{
    int deltaX = 2;
    int deltaY = 3;
    int directionX = 1;
    int directionY = 1;

    public TimerAnimation(
        int startX, int startY,
        int deltaX, int deltaY,
        int directionX, int directionY,
        int delay)
    {
        this.deltaX = deltaX;
        this.deltaY = deltaY;
        this.directionX = directionX;
        this.directionY = directionY;

        setIcon( new ImageIcon("dukewavered.gif") );
//      setIcon( new ImageIcon("copy16.gif") );
        setSize( getPreferredSize() );
        setLocation(startX, startY);
        new javax.swing.Timer(delay, this).start();
    }

    public void actionPerformed(ActionEvent e)
    {
        Container parent = getParent();

        //  Determine next X position

        int nextX = getLocation().x + (deltaX * directionX);

        if (nextX < 0)
        {
            nextX = 0;
            directionX *= -1;
        }

        if ( nextX + getSize().width > parent.getSize().width)
        {
            nextX = parent.getSize().width - getSize().width;
            directionX *= -1;
        }

        //  Determine next Y position

        int nextY = getLocation().y + (deltaY * directionY);

        if (nextY < 0)
        {
            nextY = 0;
            directionY *= -1;
        }

        if ( nextY + getSize().height > parent.getSize().height)
        {
            nextY = parent.getSize().height - getSize().height;
            directionY *= -1;
        }

        //  Move the label

        setLocation(nextX, nextY);
    }

    public static void main(String[] args)
    {
        JPanel panel = new JPanel();
        JFrame frame = new JFrame();

        frame.setContentPane(panel);
        frame.setDefaultCloseOperation( JFrame.EXIT_ON_CLOSE );
        frame.getContentPane().setLayout(null);
//      frame.getContentPane().add( new TimerAnimation(10, 10, 2, 3, 1, 1, 10) );
        frame.getContentPane().add( new TimerAnimation(300, 100, 3, 2, -1, 1, 20) );
//      frame.getContentPane().add( new TimerAnimation(0, 000, 5, 0, 1, 1, 20) );
        frame.getContentPane().add( new TimerAnimation(0, 200, 5, 0, 1, 1, 80) );
        frame.setSize(400, 400);
        frame.setLocationRelativeTo( null );
        frame.setVisible(true);
//      frame.getContentPane().add( new TimerAnimation(10, 10, 2, 3, 1, 1, 10) );
//      frame.getContentPane().add( new TimerAnimation(10, 10, 3, 0, 1, 1, 10) );
    }
}

您可以向面板添加一个 KeyListener，它会独立于图像动画运行.

You can add a KeyListener to the panel and it will operate independently of the image animation.

如何在 Java 中聆听按键时使图像移动.

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