Java KeyBindings在几秒钟后停止工作。
Java KeyBindings在几秒钟后停止工作。
提问于 2018-05-30 14:59:45
我正试着从Java KeyListeners转到KeyBindings来做动画，但它们只工作了几秒钟，然后就完全停止了。当操作触发时，我会将消息打印到控制台，而这些消息会停止，所以不只是绘图不起作用，而是在按下按键时触发了操作。
我的类扩展了JFrame，我只是向它添加了一个JPanel，并向JPanel添加了一个JLabel。我使用由操作切换的标志来指示JLabel应该如何移动，并使用JFrame的actionPerformed方法来检查标志的状态并调整JLabel的位置。
我尝试过在getInputMap方法中添加JComponent.WHEN_IN_FOCUSED_WINDOW，但没有什么不同。
代码如下：
import java.awt.Color;
import java.awt.EventQueue;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.AbstractAction;
import javax.swing.Action;
import javax.swing.JComponent;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.KeyStroke;
import javax.swing.Timer;
public class KeyBindingTest extends JFrame implements ActionListener {
long counter = 0;
int speed = 5;
boolean isUp = false, isDown = false, isLeft = false, isRight = false;
JLabel j = new JLabel();
JPanel p = new JPanel();
Timer t;
Action upPressed = new AbstractAction() {
@Override
public void actionPerformed(ActionEvent e) {
System.out.println("up on");
isUp = true;
}
};
Action upReleased = new AbstractAction() {
@Override
public void actionPerformed(ActionEvent e) {
isUp = false;
System.out.println("up off");
}
};
Action downPressed = new AbstractAction() {
@Override
public void actionPerformed(ActionEvent e) {
System.out.println("down on");
isDown = true;
}
};
Action downReleased = new AbstractAction() {
@Override
public void actionPerformed(ActionEvent e) {
System.out.println("down off");
isDown = false;
}
};
Action leftPressed = new AbstractAction() {
@Override
public void actionPerformed(ActionEvent e) {
System.out.println("left on");
isLeft = true;
}
};
Action leftReleased = new AbstractAction() {
@Override
public void actionPerformed(ActionEvent e) {
System.out.println("left off");
isLeft = false;
}
};
Action rightPressed = new AbstractAction() {
@Override
public void actionPerformed(ActionEvent e) {
System.out.println("right on");
isRight = true;
}
};
Action rightReleased = new AbstractAction() {
@Override
public void actionPerformed(ActionEvent e) {
System.out.println("right off");
isRight = false;
}
};
public static void main(String[] args) {
EventQueue.invokeLater(new Runnable() {
public void run() {
// The try/catch block prevents errors from crashing the program
try {
KeyBindingTest window = new KeyBindingTest(); // Create and setup the main game window
window.run(); // show the new window
} catch (Exception e) {
e.printStackTrace();
}
}
});
}
private void run() {
this.setBounds(640, 400, 640, 400);
this.setVisible(true);
this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
p.setBounds(0, 0, this.getWidth(), this.getHeight());
p.setVisible(true);
p.setBackground(Color.blue);
p.setOpaque(true);
p.setFocusable(true);
p.setLayout(null);
j.setBounds(320, 200, 10, 10);
j.setVisible(true);
j.setBackground(Color.red);
j.setOpaque(true);
this.add(p);
p.add(j);
p.requestFocusInWindow();
setupKeyBindings();
t = new Timer(1000 / 40, this);
t.start();
}
private void setupKeyBindings() {
p.getInputMap().put(KeyStroke.getKeyStroke("W"), "moveUp");
p.getActionMap().put("moveUp", upPressed);
p.getInputMap().put(KeyStroke.getKeyStroke("released W"), "stopUp");
p.getActionMap().put("stopUp", upReleased);
p.getInputMap().put(KeyStroke.getKeyStroke("S"), "moveDown");
p.getActionMap().put("moveDown", downPressed);
p.getInputMap().put(KeyStroke.getKeyStroke("released S"), "stopDown");
p.getActionMap().put("stopDown", downReleased);
p.getInputMap().put(KeyStroke.getKeyStroke("A"), "moveLeft");
p.getActionMap().put("moveLeft", leftPressed);
p.getInputMap().put(KeyStroke.getKeyStroke("released A"), "stopLeft");
p.getActionMap().put("stopLeft", leftReleased);
p.getInputMap().put(KeyStroke.getKeyStroke("D"), "moveRight");
p.getActionMap().put("moveRight", rightPressed);
p.getInputMap().put(KeyStroke.getKeyStroke("released D"), "stopRight");
p.getActionMap().put("stopRight", rightReleased);
}
@Override
public void actionPerformed(ActionEvent e) {
counter++;
System.out.println(counter);
if (isUp) {
j.setLocation(j.getX(), j.getY() - speed);
}
if (isDown) {
j.setLocation(j.getX(), j.getY() + speed);
}
if (isLeft) {
j.setLocation(j.getX() - speed, j.getY());
}
if (isRight) {
j.setLocation(j.getX() + speed, j.getY());
}
repaint();
}
}回答 1
Stack Overflow用户
发布于 2018-05-30 15:02:38
这是个人的事情，但是，如果您在KeyStroke.getKeyStroke("W")上使用诸如KeyStroke.getKeyStroke(KeyEvent.VK_W, 0, false)之类的东西，您通常会遇到较少的问题
KeyStroke.getKeyStroke("released W")的等价物是KeyStroke.getKeyStroke(KeyEvent.VK_W, 0, true)我已经在您的示例中反复尝试，我已经尝试用KeyStroke.getKeyStroke(KeyEvent.VK_W, 0, false)和它的等价物替换KeyStroke.getKeyStroke("W")；我已经尝试用Set替换boolean标志，但仍然存在相同的问题
然后我扔掉了你的代码，开始了一个新的项目。首先，我尝试了一种自定义的绘画路线，效果很好。然后我尝试了一种基于组件的路由，它起作用了…
所以，虽然我仍然不知道为什么它不能工作，但我有一个例子可以做到……
示例
因为我已经测试过我的建议了。
import com.sun.glass.events.KeyEvent;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.util.HashSet;
import java.util.Set;
import javax.swing.AbstractAction;
import javax.swing.ActionMap;
import javax.swing.InputMap;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.KeyStroke;
import javax.swing.Timer;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;
public class Test {
public static void main(String[] args) {
new Test();
}
public Test() {
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 TestPane());
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
});
}
public enum Input {
UP, DOWN, LEFT, RIGHT
}
public class TestPane extends JPanel {
private Set<Input> inputs = new HashSet<>();
private int delta = 4;
private JLabel label;
public TestPane() {
InputMap inputMap = getInputMap(WHEN_IN_FOCUSED_WINDOW);
ActionMap actionMap = getActionMap();
inputMap.put(KeyStroke.getKeyStroke(KeyEvent.VK_W, 0, false), "Up.pressed");
inputMap.put(KeyStroke.getKeyStroke(KeyEvent.VK_W, 0, true), "Up.relesed");
inputMap.put(KeyStroke.getKeyStroke(KeyEvent.VK_S, 0, false), "Down.pressed");
inputMap.put(KeyStroke.getKeyStroke(KeyEvent.VK_S, 0, true), "Down.relesed");
inputMap.put(KeyStroke.getKeyStroke(KeyEvent.VK_A, 0, false), "Left.pressed");
inputMap.put(KeyStroke.getKeyStroke(KeyEvent.VK_A, 0, true), "Left.relesed");
inputMap.put(KeyStroke.getKeyStroke(KeyEvent.VK_D, 0, false), "Right.pressed");
inputMap.put(KeyStroke.getKeyStroke(KeyEvent.VK_D, 0, true), "Right.relesed");
actionMap.put("Up.pressed", new InputAction(Input.UP, true));
actionMap.put("Up.relesed", new InputAction(Input.UP, false));
actionMap.put("Down.pressed", new InputAction(Input.DOWN, true));
actionMap.put("Down.relesed", new InputAction(Input.DOWN, false));
actionMap.put("Left.pressed", new InputAction(Input.LEFT, true));
actionMap.put("Left.relesed", new InputAction(Input.LEFT, false));
actionMap.put("Right.pressed", new InputAction(Input.RIGHT, true));
actionMap.put("Right.relesed", new InputAction(Input.RIGHT, false));
setLayout(null);
label = new JLabel();
label.setBackground(Color.RED);
label.setOpaque(true);
label.setBounds(0, 0, 10, 10);
add(label);
Timer timer = new Timer(5, new ActionListener() {
@Override
public void actionPerformed(ActionEvent e) {
int xPos = label.getX();
int yPos = label.getY();
if (inputs.contains(Input.UP)) {
yPos -= delta;
}
if (inputs.contains(Input.DOWN)) {
yPos += delta;
}
if (inputs.contains(Input.LEFT)) {
xPos -= delta;
}
if (inputs.contains(Input.RIGHT)) {
xPos += delta;
}
if (xPos < 0) {
xPos = 0;
} else if (xPos + 10 > getWidth()) {
xPos = getWidth() - 10;
}
if (yPos < 0) {
yPos = 0;
} else if (yPos + 10 > getHeight()) {
yPos = getHeight() - 10;
}
label.setLocation(xPos, yPos);
repaint();
}
});
timer.start();
}
@Override
public Dimension getPreferredSize() {
return new Dimension(200, 200);
}
// protected void paintComponent(Graphics g) {
// super.paintComponent(g);
// Graphics2D g2d = (Graphics2D) g.create();
// g2d.setColor(Color.RED);
// g2d.drawRect(xPos, yPos, 10, 10);
// g2d.dispose();
// }
public class InputAction extends AbstractAction {
private Input input;
private boolean pressed;
public InputAction(Input input, boolean pressed) {
this.input = input;
this.pressed = pressed;
}
@Override
public void actionPerformed(ActionEvent e) {
if (pressed) {
inputs.add(input);
} else {
inputs.remove(input);
}
}
}
}
}附注：
这种“类型”的问题最近被问得很多，我认为这是某种类型的类分配，因为我们已经看到了这种代码风格的许多变体。正如我们反复建议的那样，以这种方式使用组件是不明智的，它们实际上不是为这种事情而设计的。您将使用自定义绘制路线获得更好(也更容易)的结果，如Make an JLabel move with Key Bidings中所示
页面原文内容由Stack Overflow提供。腾讯云小微IT领域专用引擎提供翻译支持
原文链接：
https://stackoverflow.com/questions/50598222
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