Java 如何检查用户是否按下了某个键？
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How do I check if the user is pressing a key?
提问by Saucymeatman
In java I have a program that needs to check continuously if a user is pressing a key. So In psuedocode, somthing like
在 Java 中，我有一个程序需要不断检查用户是否按下了某个键。所以在伪代码中，有点像
if (isPressing("w"))
{
//do somthing
}
Thanks in advance!
提前致谢！
采纳答案by Elist
In java you don't check if a key is pressed, instead you listento KeyEvents.
The right way to achieve your goal is to register a KeyEventDispatcher, and implement it to maintain the state of the desired key:
在Java中，你不检查是否有键被按下，而不是你听到KeyEvent秒。实现目标的正确方法是注册一个KeyEventDispatcher，并实施它以维护所需密钥的状态：
import java.awt.KeyEventDispatcher;
import java.awt.KeyboardFocusManager;
import java.awt.event.KeyEvent;
public class IsKeyPressed {
private static volatile boolean wPressed = false;
public static boolean isWPressed() {
synchronized (IsKeyPressed.class) {
return wPressed;
}
}
public static void main(String[] args) {
KeyboardFocusManager.getCurrentKeyboardFocusManager().addKeyEventDispatcher(new KeyEventDispatcher() {
@Override
public boolean dispatchKeyEvent(KeyEvent ke) {
synchronized (IsKeyPressed.class) {
switch (ke.getID()) {
case KeyEvent.KEY_PRESSED:
if (ke.getKeyCode() == KeyEvent.VK_W) {
wPressed = true;
}
break;
case KeyEvent.KEY_RELEASED:
if (ke.getKeyCode() == KeyEvent.VK_W) {
wPressed = false;
}
break;
}
return false;
}
}
});
}
}
Then you can always use:
然后你可以随时使用：
if (IsKeyPressed.isWPressed()) {
// do your thing.
}
You can, of course, use same method to implement isPressing("<some key>")with a map of keys and their state wrapped inside IsKeyPressed.
当然，您可以使用相同的方法来实现isPressing("<some key>")包含在IsKeyPressed.
回答by Java Panter
You have to implement KeyListener,take a look here:
http://docs.oracle.com/javase/7/docs/api/java/awt/event/KeyListener.html
你必须实现KeyListener，看看这里：http:
//docs.oracle.com/javase/7/docs/api/java/awt/event/KeyListener.html
More details on how to use it: http://docs.oracle.com/javase/tutorial/uiswing/events/keylistener.html
有关如何使用它的更多详细信息：http: //docs.oracle.com/javase/tutorial/uiswing/events/keylistener.html
回答by Simmant
Try this:
尝试这个：
import java.awt.event.KeyAdapter;
import java.awt.event.KeyEvent;
import javax.swing.JFrame;
import javax.swing.JTextField;
public class Main {
public static void main(String[] argv) throws Exception {
JTextField textField = new JTextField();
textField.addKeyListener(new Keychecker());
JFrame jframe = new JFrame();
jframe.add(textField);
jframe.setSize(400, 350);
jframe.setVisible(true);
}
class Keychecker extends KeyAdapter {
@Override
public void keyPressed(KeyEvent event) {
char ch = event.getKeyChar();
System.out.println(event.getKeyChar());
}
}
