在关注JpopupMenu（Java）的同时检测键盘输入

Question

我想知道在关注JpopupMenu时是否有任何方法可以检测键盘输入。这是为了在键盘输入检测时删除对JPopupMenu的关注。这可能吗？

谢谢。

以下是我编写的简化代码。

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.event.CaretEvent;
import javax.swing.event.CaretListener;
import javax.swing.event.ChangeListener;
import javax.swing.event.ChangeEvent;
import java.net.*;

import java.io.*;


public class testClass {
   static JPopupMenu textPopupMenu = new JPopupMenu("MENU");
  final static JTextArea textInput = new JTextArea(50,80);

    final static JPanel overallPanel = new JPanel();
  final static JFrame overallFrame = new JFrame("Test");
    public static void main(String[] args)
    {
                SwingUtilities.invokeLater(new Runnable()
                {
                    @Override
                    public void run()
                    {
                        final ActionListener actionListener1 = new ActionListener() {
                            public void actionPerformed(ActionEvent actionEvent) {
                                textPopupMenu.setFocusable(false);
                            }
                          };
                        KeyListener textInputListener = new KeyAdapter()
                        {
                            @Override
                            public void keyPressed(KeyEvent e)
                            {
                              //Get the suggested words from the function and populate them to the JMenuItem
                              textPopupMenu = new JPopupMenu("MENU");
                              for(int i=0;i<5;i++)
                              {
                                switch(i)
                                {
                                    case 0:
                                      JMenuItem item1 = new JMenuItem("A");
                                      textPopupMenu.add(item1);
                                      break;

                                    case 1:
                                      JMenuItem item2 = new JMenuItem("B");
                                      textPopupMenu.add(item2);
                                      break;

                                    case 2:
                                      JMenuItem item3 = new JMenuItem("C");
                                      textPopupMenu.add(item3);
                                      break;

                                    case 3:
                                      JMenuItem item4 = new JMenuItem("D");
                                      textPopupMenu.add(item4);
                                      break;

                                    case 4:
                                      JMenuItem item5 = new JMenuItem("E");
                                      textPopupMenu.add(item5);
                                      break;
                                };
                              }
                                textPopupMenu.setFocusable(true);
                                if (textPopupMenu.isVisible())
                                {
                                    textPopupMenu.setLocation(0, 0 + 20);
                                }
                                else
                                {
                                    textPopupMenu.show(textInput,0, 0 + 20);
                                }
                            }
                        };

                        textInput.addKeyListener(textInputListener);
                        overallPanel.add(textInput);

                        overallFrame.getContentPane().add(overallPanel);
                        overallFrame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);`enter code here`
                        overallFrame.setSize(1000, 900);
                        overallFrame.setLocationRelativeTo(null);
                        overallFrame.setVisible(true);
                    }
                });
    }

}

Answer 1

我不太确定他们为什么会这样做，但你必须使用JPopupMenu.addMenuKeyListener()。

当我测试这个时，事件被传递了两次，所以我必须存储从event.getWhen()获得的最后一个事件的时间，并且只处理比上次存储时间更新的事件。

Answer 2

是的，可以使用registerKeyboardAction

  KeyStroke keystroke = KeyStroke.getKeyStroke(KeyEvent.VK_PERIOD, 0, false);
  jpopMenu.registerKeyboardAction(actionListener, keystroke, JComponent.WHEN_FOCUSED);

JComponent.WHEN_FOCUSED将允许您在JPopMenu聚焦时从键盘输入检测。