问题
I have some code that I need to modify. In the code, the original author uses KeyStroke.getKeyStroke
to take user input. In this code, for example, he uses a
instead of left arrow.
I want to change this, but I don't know how.
Here is the original code:
registerKeyboardAction(
new ActionListener() {
public void actionPerformed(ActionEvent e) {
tick(RIGHT);
}
}, "right", KeyStroke.getKeyStroke('d'), WHEN_IN_FOCUSED_WINDOW
);
I have to change it to something like this, but when run, it doesn't work:
KeyStroke.getKeyStroke(KeyEvent.VK_RIGHT);
KeyStroke.getKeyStroke("RIGHT");
回答1:
Do start the program by pressing the DOWN ARROW KEY
, to watch the string first. Here have a look at this example program :
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
public class KeyBindingExample
{
private void createAndDisplayGUI()
{
JFrame frame = new JFrame("Key Binding Example");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
DrawingPanel contentPane = new DrawingPanel();
frame.setContentPane(contentPane);
frame.pack();
frame.setLocationByPlatform(true);
frame.setVisible(true);
contentPane.requestFocusInWindow();
}
public static void main(String... args)
{
SwingUtilities.invokeLater(new Runnable()
{
public void run()
{
new KeyBindingExample().createAndDisplayGUI();
}
});
}
}
class DrawingPanel extends JPanel
{
private int x;
private int y;
private String[] commands = {
"UP",
"DOWN",
"LEFT",
"RIGHT"
};
private ActionListener panelAction = new ActionListener()
{
@Override
public void actionPerformed(ActionEvent ae)
{
String command = (String) ae.getActionCommand();
if (command.equals(commands[0]))
y -= 1;
else if (command.equals(commands[1]))
y += 1;
else if (command.equals(commands[2]))
x -= 1;
else if (command.equals(commands[3]))
x += 1;
repaint();
}
};
public DrawingPanel()
{
x = 0;
y = 0;
for (int i = 0; i < commands.length; i++)
registerKeyboardAction(panelAction,
commands[i],
KeyStroke.getKeyStroke(commands[i]),
JComponent.WHEN_IN_FOCUSED_WINDOW);
}
@Override
public Dimension getPreferredSize()
{
return (new Dimension(500, 300));
}
@Override
public void paintComponent(Graphics g)
{
super.paintComponent(g);
String displayText = "X : " + x + " and Y : " + y;
System.out.println(displayText);
g.drawString(displayText, x, y);
}
}
回答2:
You should be able to use KeyStroke.getKeyStroke("DOWN");
, "UP"
, "LEFT"
, "RIGHT"
, to do what you want.
See the javadoc for more detail.
来源:https://stackoverflow.com/questions/11171021/java-use-keystroke-with-arrow-key