我有一个JPanel,它使用KeyListener作为内容窗格作为窗口;但是,JPanel顶部的网格布局中有按钮和文本字段。
如何在编辑文本或单击按钮后保留焦点的JPanel焦点的优先级,以便我可以读取键输入?
答案 0 :(得分:0)
您只需在FocusListener
事件上添加focusLost
,然后再次请求重点关注。像这样:
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
public class JPanelFocus {
public static void main(String... argv) throws Exception {
EventQueue.invokeLater(new Runnable() {
public void run() {
JFrame f = new JFrame("FocusTest");
JButton b = new JButton("Button");
final JPanel p = new JPanel();
p.add(b);
// Here is the KeyListener installed on our JPanel
p.addKeyListener(new KeyAdapter() {
public void keyTyped(KeyEvent ev) {
System.out.println(ev.getKeyChar());
}
});
// This is the bit that does the magic - make sure
// that our JPanel is always focussed
p.addFocusListener(new FocusAdapter() {
public void focusLost(FocusEvent ev) {
p.requestFocus();
}
});
f.getContentPane().add(p);
f.pack();
f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
f.setVisible(true);
// Make sure JPanel starts with the focus
p.requestFocus();
}
});
}
}
如果你有需要保持焦点的字段(你提到了一个可编辑的文本字段),这将不起作用。关键事件应何时转到文本字段,何时应转到JPanel?
答案 1 :(得分:0)
作为替代方案,您也可以使子组件不可聚焦。
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
class MyPanel extends JPanel implements KeyListener {
public MyPanel() {
this.setFocusable(true);
this.addKeyListener(this);
// for each component
JComboBox<String> comboBox = new JComboBox<String>();
comboBox.addItem("Item1");
this.add(comboBox);
// this is what keeps each child from intercepting KeyEvents
comboBox.setFocusable(false);
}
public void keyPressed(KeyEvent e) { ... }
public void keyTyped(KeyEvent e) { ... }
public void keyReleased(KeyEvent e) { ... }
public static void main(String[] args) {
// create a frame
JFrame frame = new JFrame();
frame.setSize(640, 480);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
// add MyPanel to frame
MyPanel panel = new MyPanel();
frame.add(panel);
frame.setVisible(true);
}
}