如何从另一个类更改Java框架的背景色?
我有以下资料:如何从另一个类更改Java框架的背景色?,java,swing,jpanel,keyevent,Java,Swing,Jpanel,Keyevent,我有以下资料: import javax.swing.JFrame; public class Directions { public Directions(){ JFrame frame = new JFrame("Direction"); frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); frame.getContentPane().add(new DirectionPane
import javax.swing.JFrame;
public class Directions {
public Directions(){
JFrame frame = new JFrame("Direction");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.getContentPane().add(new DirectionPanel());
frame.pack();
frame.setVisible(true);
}
public static void main(String[] args) {
Directions myTest = new Directions();
}
}
二等舱:
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
public class DirectionPanel extends JPanel{
public DirectionPanel(){
addKeyListener(new DirectionListener());
setBackground(Color.yellow);
}
private class DirectionListener implements KeyListener{
@Override
public void keyPressed(KeyEvent e) {
//JOptionPane.showMessageDialog(null, "Hello Johnny");
int keyCode = e.getKeyCode();
if (keyCode == KeyEvent.VK_LEFT){
setBackground(Color.red);
}
repaint();
}
@Override
public void keyReleased(KeyEvent e) {
// TODO Auto-generated method stub
}
@Override
public void keyTyped(KeyEvent e) {
// TODO Auto-generated method stub
}
}
}
为什么当我按左箭头时边框没有变红?我也有没有键代码测试的想法,无论是关键,它会工作,但它没有。多谢各位
public DirectionPanel(){
addKeyListener(new DirectionListener());
setFocusable(true);// INSERT THIS
setBackground(Color.yellow);
}
JPanel需要聚焦以接收KeyEvents
JPanel需要可聚焦以接收KeyEvents当使用键盘时,Swing组件应使用not KeyListener来调用操作。这样做的一个附带好处是,您不必担心焦点问题
Action left = new AbstractAction()
{
public void actionPerformed(ActionEvent e)
{
System.out.println( "Left" );
}
};
Object key1 = "left";
KeyStroke ks1 = KeyStroke.getKeyStroke(KeyEvent.VK_LEFT, 0);
panel.getInputMap(JPanel.WHEN_ANCESTOR_OF_FOCUSED_COMPONENT).put(ks1, key1);
panel.getActionMap().put(key1, left);
当使用键盘时,Swing组件应该使用not键侦听器来调用操作。这样做的一个附带好处是,您不必担心焦点问题
Action left = new AbstractAction()
{
public void actionPerformed(ActionEvent e)
{
System.out.println( "Left" );
}
};
Object key1 = "left";
KeyStroke ks1 = KeyStroke.getKeyStroke(KeyEvent.VK_LEFT, 0);
panel.getInputMap(JPanel.WHEN_ANCESTOR_OF_FOCUSED_COMPONENT).put(ks1, key1);
panel.getActionMap().put(key1, left);
弹出消息在未注释时是否出现?否。弹出失败。我想这是一个弹出窗口,所以我选择了一些更简单的方法,比如颜色更改,但也失败了。弹出消息在未注释时出现了吗?没有。弹出窗口失败了。我想这是一个弹出窗口,所以我选择了一些更简单的方法,比如颜色更改,但也失败了。参考:。我正要回答同样的问题。参考文献:。我正要回答同样的问题。