问题描述
我有一个带有搜索栏的菜单栏,该菜单栏是通过JTextField
实现的,如下所示:
public class Ui_Frame {
private static JFrame f;
private static DrawPanel drawPanel;
public static void main(String[] args) {
SwingUtilities.invokelater(Ui_Frame::createAndShowGUI);
}
private static void createAndShowGUI() {
f = new JFrame("Frame");
drawPanel = new DrawPanel(); //A class that extends JPanel where I draw
JMenuBar menubar = new JMenuBar();
JMenu j_menu_data = new JMenu("Data");
JTextField j_menu_searchfield = new JTextField();
j_menu_searchfield.setSize(new Dimension(100,20));
menubar.add(j_menu_data);
menubar.add(j_menu_searchfield);
f.setJMenuBar(menubar);
f.setDefaultCloSEOperation(JFrame.EXIT_ON_CLOSE);
f.add(drawPanel);
f.pack();
f.setVisible(true);
}
}
我有KeyListener
类的DrawPanel
,这些都很好。问题是,当我如上所述将搜索栏JTextField
添加到菜单栏时,我编写的所有内容均被写入文本字段,并且不会触发我的键侦听器。我无法“退出”文本字段,因此,如果我在绘制图形的区域内单击,则所按的所有键仍会保留在文本字段中。
我为getFocus()
尝试过DrawPanel
,但无济于事。
如何解决这个问题?
编辑: DrawPanel类,因此您具有运行它所需的所有类:
public class DrawPanel extends JPanel {
public DrawPanel() {
addKeyListener(new CustomKeyListener());
this.setBackground(new Color(220,220,220));
setBorder(BorderFactory.createLineBorder(Color.black));
setFocusable(true);
setVisible(true);
}
public Dimension getPreferredSize() {
return new Dimension(500,500);
}
protected void paintComponent(Graphics g) {
Graphics2D g2D = (Graphics2D) g;
super.paintComponent(g2D);
}
class CustomKeyListener implements KeyListener {
@Override
public void keyTyped(KeyEvent e) {
if (e.getKeyChar() == KeyEvent.VK_SPACE) {
System.out.println("pressed SPACE");
}
}
@Override
public void keypressed(KeyEvent e) { }
@Override
public void keyreleased(KeyEvent e) { }
}
}
解决方法
启动 Swing 应用程序时,JTextField
最初具有键盘焦点。知道这一点是因为您看到光标在JTextField
内部闪烁。
用鼠标单击DrawPanel
不会将键盘焦点转移到DrawPanel
。您知道这一点是因为在DrawPanel
内单击鼠标后,光标仍在JTextField
内闪烁。
您可以通过点击键盘上的TAB键将键盘焦点从JTextField
转移到DrawPanel
,因为这是默认的焦点遍历键。您知道JTextField
不再具有键盘焦点,因为其中没有闪烁的光标。
如果您确实希望DrawPanel
通过单击鼠标来获得键盘焦点,则可以在MouseListener
上添加DrawPanel
,如下面的代码所示,它实际上是您的代码(用于类DrawPanel
)并添加了MouseListener
。
请注意,我没有更改课程Ui_Frame
。
import java.awt.Color;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.event.KeyEvent;
import java.awt.event.KeyListener;
import java.awt.event.MouseEvent;
import java.awt.event.MouseListener;
import javax.swing.BorderFactory;
import javax.swing.JPanel;
public class DrawPanel extends JPanel implements MouseListener {
public DrawPanel() {
addKeyListener(new CustomKeyListener());
addMouseListener(this);
this.setBackground(new Color(220,220,220));
setBorder(BorderFactory.createLineBorder(Color.black));
setFocusable(true);
setVisible(true);
}
public Dimension getPreferredSize() {
return new Dimension(500,500);
}
protected void paintComponent(Graphics g) {
Graphics2D g2D = (Graphics2D) g;
super.paintComponent(g2D);
}
class CustomKeyListener implements KeyListener {
@Override
public void keyTyped(KeyEvent e) {
if (e.getKeyChar() == KeyEvent.VK_SPACE) {
System.out.println("Pressed SPACE");
}
}
@Override
public void keyPressed(KeyEvent e) { }
@Override
public void keyReleased(KeyEvent e) { }
}
@Override
public void mouseClicked(MouseEvent mouseEvent) {
System.out.println(this.requestFocusInWindow());
}
@Override
public void mousePressed(MouseEvent mouseEvent) {
}
@Override
public void mouseReleased(MouseEvent mouseEvent) {
}
@Override
public void mouseEntered(MouseEvent mouseEvent) {
}
@Override
public void mouseExited(MouseEvent mouseEvent) {
}
}
请注意,方法requestFocusInWindow()
成功返回true
。