[英]Dr java keylistener help object move after key is released
我正在尝试创建一个程序,在该程序中,除非用户按下空格,否则对象会连续落在屏幕上,在这种情况下,对象会向上移动。 到目前为止,我已经有了运行该程序时该对象最初开始下降的功能。 当我按空格键时,对象会向上移动(应该如此)。 但是,当我释放钥匙时,对象停止移动。 我希望它在释放钥匙时继续下降。
我已经看过使用键绑定而不是keylistener,但是我遇到了麻烦。 我是一名高中生,希望攻读计算机科学专业,所以请原谅我不知道太多高级编码术语/方法。 但是,我是班上最好的学生之一,也是一个急于解决这个问题的快速学习者。 这是我的代码:
public class htestnew extends JPanel implements ActionListener, KeyListener {
Timer t = new Timer(5, this);
int x = 20, y = 20, vely = 1;
public htestnew() {
t.start();
addKeyListener(this);
setFocusable(true);
setFocusTraversalKeysEnabled(false);
}
public void paintComponent(Graphics g) {
super.paintComponent(g);
ImageIcon background = new ImageIcon("OBJECTEXAMPLE1");
background.paintIcon(this, g, 0, 0);
}
public void actionPerformed(ActionEvent e) {
if (y < 0)
{
vely = 0;
y = 0;
}
if (y > 305) //-70
{
vely = 0;
y = 305;
}
y += vely;
repaint();
}
public void keyPressed(KeyEvent e) {
int code = e.getKeyCode();
if (code == KeyEvent.VK_SPACE) {
vely = -1;
}
}
public void keyTyped(KeyEvent e) {
}
public void keyReleased(KeyEvent e) {
vely = 0;
//I have tried setting this value to 1 but it does not work
}
如果更容易使用键绑定,那么一个个人的,易于遵循的示例将是很棒的。 谢谢。
所以,改变...
public void keyReleased(KeyEvent e) {
vely=0;
//I have tried setting this value to 1 but it does not work
}
至...
public void keyReleased(KeyEvent e) {
vely=1;
//I have tried setting this value to 1 but it does not work
}
基本上使它工作(在我添加了一些实际绘制的东西之后)
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.Graphics;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.KeyEvent;
import java.awt.event.KeyListener;
import javax.swing.ImageIcon;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.Timer;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;
public class Test 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 Test());
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
});
}
Timer t = new Timer(5, this);
int x = 20, y = 20, vely = 1;
public Test() {
t.start();
addKeyListener(this);
setFocusable(true);
setFocusTraversalKeysEnabled(false);
}
@Override
public Dimension getPreferredSize() {
return new Dimension(300, 300);
}
@Override
public void paintComponent(Graphics g) {
super.paintComponent(g);
g.drawRect(x, y, 5, 5);
}
public void actionPerformed(ActionEvent e) {
if (y < 0) {
vely = 0;
y = 0;
}
if (y > 305) //-70
{
vely = 0;
y = 305;
}
y += vely;
repaint();
}
public void keyPressed(KeyEvent e) {
int code = e.getKeyCode();
if (code == KeyEvent.VK_SPACE) {
vely = -1;
}
}
public void keyTyped(KeyEvent e) {
}
public void keyReleased(KeyEvent e) {
vely = 1;
//I have tried setting this value to 1 but it does not work
}
}
我强烈建议您看看如何使用键绑定而不是使用KeyListener
,它将解决KeyListener
的核心问题
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.Graphics;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.KeyEvent;
import java.awt.event.KeyListener;
import javax.swing.AbstractAction;
import javax.swing.Action;
import javax.swing.ActionMap;
import javax.swing.InputMap;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.KeyStroke;
import javax.swing.Timer;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;
public class Test extends JPanel implements ActionListener {
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 Test());
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
});
}
Timer t = new Timer(5, this);
int x = 20, y = 20, vely = 1;
public Test() {
t.start();
addKeyBinding("space.pressed", KeyEvent.VK_SPACE, true, new ChangeYAction(-1));
addKeyBinding("space.released", KeyEvent.VK_SPACE, false, new ChangeYAction(1));
}
protected void addKeyBinding(String name, int virtualKey, boolean pressed, Action action) {
addKeyBinding(name, KeyStroke.getKeyStroke(virtualKey, 0, !pressed), action);
}
protected void addKeyBinding(String name, KeyStroke keyStroke, Action action) {
InputMap im = getInputMap(WHEN_IN_FOCUSED_WINDOW);
ActionMap am = getActionMap();
im.put(keyStroke, name);
am.put(name, action);
}
@Override
public Dimension getPreferredSize() {
return new Dimension(300, 300);
}
@Override
public void paintComponent(Graphics g) {
super.paintComponent(g);
g.drawRect(x, y, 5, 5);
}
public void actionPerformed(ActionEvent e) {
if (y < 0) {
vely = 0;
y = 0;
}
if (y > 305) //-70
{
vely = 0;
y = 305;
}
y += vely;
repaint();
}
public class ChangeYAction extends AbstractAction {
private int changeYTo;
public ChangeYAction(int changeYTo) {
this.changeYTo = changeYTo;
}
@Override
public void actionPerformed(ActionEvent e) {
vely = changeYTo;
}
}
}
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