我有没有正确地构建这个关键监听器？ [英] Did I structure this key listener properly?
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问题描述
我这么问是因为我想在我的的GamePanel 类的<code> addShot（）方法被调用时，用户点击<大骨节病>输入，这个初始化一个镜头对象重新presenting从船上发射了一枚导弹，但它不会做任何事情。是否有知名度的问题在这里，还是我只是在结构关键事件和监听的关系错了吗？我只张贴相关code，但如果需要，我可以张贴的其余部分。
这里的code：
公共静态类的GameTest扩展的JFrame { 私有静态最终诠释WINDOW_WIDTH = 800;
私有静态最终诠释WINDOW_HEIGHT = 500;
公众的GamePanel的GamePanel;
公众的GameTest（）抛出IOException
超（炸自由）;
的setResizable（假）;
setDefaultCloseOperation（JFrame.EXIT_ON_CLOSE）;
的setSize（WINDOW_WIDTH，WINDOW_HEIGHT）;
的setLayout（新的BorderLayout（））;
的GamePanel =新的GamePanel（）;
添加（的GamePanel）;
中心（本）;
调用setVisible（真）;
this.addKeyListener（新aKeyListener（））;
this.setFocusable（真）; } //结束构造 公共无效中心（JFrame的帧）{
GraphicsEnvironment中GE = GraphicsEnvironment.getLocalGraphicsEnvironment（）;
点中心= ge.getCenterPoint（）; INT W = frame.getWidth（）;
INT H = frame.getHeight（）; INT X = center.x - 瓦特/ 2，Y = center.y - H / 2;
frame.setBounds（X，Y，W，H）;
frame.validate（）;
中心的方法} //结束 公共类aKeyListener实现的KeyListener { @覆盖
公共无效的keyTyped（KeyEvent的E）{
} //结束时清空法的keyTyped @覆盖
公共无效键pressed（KeyEvent的E）{
开关（e.getKey code（））{
案例KeyEvent.VK_A：
Launcher.lRun = -20;
gamePanel.move（的GamePanel）;
打破;
案例KeyEvent.VK_D：
Launcher.lRun = 20;
gamePanel.move（的GamePanel）;
打破;
案例KeyEvent.VK_ENTER：
gamePanel.addShot（）;
打破;
默认：
Launcher.lRun = 0;
} } //结束键pressed方法 @覆盖
公共无效调用keyReleased（KeyEvent的E）{
} //结束时清空的keyReleased方法 } //结束aKeyListener类} //结束的GameTest类
解决方案
- 此致可能是一个焦点问题 - 这是在的GamePanel偷焦点也许，一个非常常见的有KeyListeners问题 。
- 一般的建议：用按键绑定，而不是这种类型的需求的KeyListener的青睐
相关链接：
修改结果
例如：
进口java.awt.Dimension中;
进口java.awt.event.ActionEvent中;
进口java.awt.event.KeyEvent中;进口的javax.swing *。公共类的GameTest扩展的JFrame { 私有静态最终诠释WINDOW_WIDTH = 800;
私有静态最终诠释WINDOW_HEIGHT = 500;
公众的GamePanel的GamePanel; 公众的GameTest（）{
超（炸自由）;
的setResizable（假）;
// setDefaultCloseOperation（JFrame.EXIT_ON_CLOSE）;
setDefaultCloseOperation（JFrame.DISPOSE_ON_CLOSE）;
//的setSize（WINDOW_WIDTH，WINDOW_HEIGHT）; //永远不要这样做
的GamePanel =新的GamePanel（）;
setUpKeyBinding（的GamePanel）;
添加（的GamePanel）;
包（）;
setLocationRelativeTo（NULL）; //为中心！
调用setVisible（真）;
} @覆盖
公共尺寸的get preferredSize（）{
返回新的Dimension（WINDOW_WIDTH，WINDOW_HEIGHT）;
} 私人无效setUpKeyBinding（的GamePanel gamePanel2）{ //只需要窗口具有焦点
INT条件= JComponent.WHEN_IN_FOCUSED_WINDOW; //获取的GamePanel的的InputMap和ActionMap中，因为这些将被用来设置
//我们的键绑定
InputMap中的InputMap = gamePanel2.getInputMap（条件）;
ActionMap中的ActionMap = gamePanel2.getActionMap（）; //绑定一个重要回迁20个像素
的KeyStroke keyStroke的= KeyStroke.getKeyStroke（KeyEvent.VK_A，0）;
inputMap.put（击键keyStroke.toString（））;
actionMap.put（keyStroke.toString（），新MoveAction（gamePanel2，-20））; //绑定D键向前移动20个像素
keyStroke的= KeyStroke.getKeyStroke（KeyEvent.VK_D，0）;
inputMap.put（击键keyStroke.toString（））;
actionMap.put（keyStroke.toString（），新MoveAction（gamePanel2，20））; //绑定ENTER键
keyStroke的= KeyStroke.getKeyStroke（KeyEvent.VK_ENTER，0）;
inputMap.put（击键keyStroke.toString（））;
actionMap.put（keyStroke.toString（），新EnterAction（gamePanel2））; } 公共静态无效的主要（字串[] args）{
新的GameTest（）;
} 这将势必击键//我们的Action类
私有类MoveAction扩展AbstractAction {
私人的GamePanel gamePanel2;
私人诠释距离; 公共MoveAction（的GamePanel gamePanel2，诠释距离）{
this.gamePanel2 = gamePanel2;
this.distance =距离;
} @覆盖
公共无效的actionPerformed（ActionEvent的五）{
gamePanel2.moveItem（距离）;
}
} 私有类EnterAction扩展AbstractAction {
私人的GamePanel gamePanel2; 公共EnterAction（的GamePanel gamePanel2）{
this.gamePanel2 = gamePanel2;
} @覆盖
公共无效的actionPerformed（ActionEvent的五）{
gamePanel2.addShot（）;
}
}}//一个简单的GamePanel类只表示一切正在按预期
一流的GamePanel继承JPanel { 公共无效移动选项（int i）以{
//你的移动选项的方法，而不是将实际移动的东西，我的距离
的System.out.println（移动项目方法的距离：+ I）;
} 公共无效addShot（）{
//你的addShot方法将实际拍摄
的System.out.println（添加拍摄法）;
}}
I'm asking because I want the addShot() method in my GamePanel class to be called when the user hits enter," this initializes a shot object representing a missile fired from a ship, but it doesn't do anything. Is there a visibility issue here, or did I just structure the key event and listener relationship wrong? I'm only posting relevant code, but I can post the rest if necessary.
Here's the code:
public static class GameTest extends JFrame {
private static final int WINDOW_WIDTH = 800;
private static final int WINDOW_HEIGHT = 500;
public GamePanel gamePanel;
public GameTest() throws IOException {
super("Deep Fried Freedom");
setResizable(false);
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
setSize(WINDOW_WIDTH, WINDOW_HEIGHT);
setLayout(new BorderLayout());
gamePanel = new GamePanel();
add(gamePanel);
center(this);
setVisible(true);
this.addKeyListener(new aKeyListener());
this.setFocusable(true);
} // end constructor
public void center(JFrame frame) {
GraphicsEnvironment ge = GraphicsEnvironment.getLocalGraphicsEnvironment();
Point center = ge.getCenterPoint();
int w = frame.getWidth();
int h = frame.getHeight();
int x = center.x - w / 2, y = center.y - h / 2;
frame.setBounds(x, y, w, h);
frame.validate();
}//end of center method
public class aKeyListener implements KeyListener {
@Override
public void keyTyped(KeyEvent e) {
}//end empty keyTyped method
@Override
public void keyPressed(KeyEvent e) {
switch (e.getKeyCode()) {
case KeyEvent.VK_A:
Launcher.lRun = -20;
gamePanel.move(gamePanel);
break;
case KeyEvent.VK_D:
Launcher.lRun = 20;
gamePanel.move(gamePanel);
break;
case KeyEvent.VK_ENTER:
gamePanel.addShot();
break;
default:
Launcher.lRun = 0;
}
}//end keyPressed method
@Override
public void keyReleased(KeyEvent e) {
}//end empty keyReleased method
}//end aKeyListener class
}//end GameTest class
解决方案
- Yours is likely a focus issue -- something in the GamePanel stealing focus perhaps, a very common problem with KeyListeners.
- General advice: favor using Key Bindings, not a KeyListener for this type of need.
Useful links:
- Swing Resources
- Please check my second example program in my answer to a StackOverflow question here.
- Overall Swing Tutorials
- Key Bindings
- Swing Timer
- Concurrency in Swing
Edit
For example:
import java.awt.Dimension;
import java.awt.event.ActionEvent;
import java.awt.event.KeyEvent;
import javax.swing.*;
public class GameTest extends JFrame {
private static final int WINDOW_WIDTH = 800;
private static final int WINDOW_HEIGHT = 500;
public GamePanel gamePanel;
public GameTest() {
super("Deep Fried Freedom");
setResizable(false);
// setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
// setSize(WINDOW_WIDTH, WINDOW_HEIGHT); // never do this
gamePanel = new GamePanel();
setUpKeyBinding(gamePanel);
add(gamePanel);
pack();
setLocationRelativeTo(null); // to center!
setVisible(true);
}
@Override
public Dimension getPreferredSize() {
return new Dimension(WINDOW_WIDTH, WINDOW_HEIGHT);
}
private void setUpKeyBinding(GamePanel gamePanel2) {
// only need window to have focus
int condition = JComponent.WHEN_IN_FOCUSED_WINDOW;
// get the GamePanel's InputMap and ActionMap as these will be used to set
// up our Key Bindings
InputMap inputMap = gamePanel2.getInputMap(condition);
ActionMap actionMap = gamePanel2.getActionMap();
// bind the A key to move back 20 pixels
KeyStroke keyStroke = KeyStroke.getKeyStroke(KeyEvent.VK_A, 0);
inputMap.put(keyStroke, keyStroke.toString());
actionMap.put(keyStroke.toString(), new MoveAction(gamePanel2, -20));
// bind the D key to move forward 20 pixels
keyStroke = KeyStroke.getKeyStroke(KeyEvent.VK_D, 0);
inputMap.put(keyStroke, keyStroke.toString());
actionMap.put(keyStroke.toString(), new MoveAction(gamePanel2, 20));
// bind the ENTER key
keyStroke = KeyStroke.getKeyStroke(KeyEvent.VK_ENTER, 0);
inputMap.put(keyStroke, keyStroke.toString());
actionMap.put(keyStroke.toString(), new EnterAction(gamePanel2));
}
public static void main(String[] args) {
new GameTest();
}
// our Action classes that will bound to key strokes
private class MoveAction extends AbstractAction {
private GamePanel gamePanel2;
private int distance;
public MoveAction(GamePanel gamePanel2, int distance) {
this.gamePanel2 = gamePanel2;
this.distance = distance;
}
@Override
public void actionPerformed(ActionEvent e) {
gamePanel2.moveItem(distance);
}
}
private class EnterAction extends AbstractAction {
private GamePanel gamePanel2;
public EnterAction(GamePanel gamePanel2) {
this.gamePanel2 = gamePanel2;
}
@Override
public void actionPerformed(ActionEvent e) {
gamePanel2.addShot();
}
}
}
// a trivial GamePanel class to just show that everything is working as expected
class GamePanel extends JPanel {
public void moveItem(int i) {
// your moveItem method will instead actually move something, a distance of i
System.out.println("Move Item Method distance: " + i);
}
public void addShot() {
// your addShot method will actually shoot
System.out.println("Add Shot Method");
}
}
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