java - 是否可以使用按键监听器显示以前隐藏的 JFrame

Question

这是我的代码，我基本上只是为最常见的监听器做了一个测试器，我稍后可能会在未来的项目中使用它，主要问题是在底部的关键监听器中，我正在尝试重新显示框架，但是我认为不能那样做，请帮忙ps:不知道为什么导入没有正确显示。

package newpackage;

import java.awt.Color;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JTextField;
import javax.swing.JSeparator;
import java.awt.event.ActionListener;
import java.awt.event.ActionEvent;
import java.awt.event.KeyEvent;
import java.awt.event.KeyListener;
import java.awt.event.MouseEvent;
import java.awt.event.MouseListener;
import javax.swing.JTextArea;
import javax.swing.SwingUtilities;
import javax.swing.UIManager;

public class NewClass1 extends JFrame {


private JLabel item1,infomouse,infoclicks,infoKeys,writehere;
private JButton button1,button2,button3;
private JTextArea text1,status,KeyStatus;
private JTextField text2,text3,mouse,clicks,test;
private JSeparator sep1;
private int clicknumber;

public NewClass1() {
    super("Listener Tests");
    setLayout(null);
    sep1 = new JSeparator();

    button1 = new JButton("Button1");
    button2 = new JButton("Button2");
    button3 = new JButton("Button3");
    item1 = new JLabel("Button Status :");
    infomouse = new JLabel("Mouse Status :");
    infoclicks = new JLabel("Nº of clicks :");
    infoKeys = new JLabel("Keyboard status:");
    writehere = new JLabel("Write here: ");


    text1 = new JTextArea();
    text2 = new JTextField(20);
    text3 = new JTextField(20);
    status = new JTextArea();
    mouse  = new JTextField(20);
    clicks = new JTextField(4);
    KeyStatus = new JTextArea();
    test = new JTextField(3);
    clicks.setText(String.valueOf(clicknumber));

    text1.setEditable(true);
    text2.setEditable(false);
    text3.setEditable(false);
    status.setEditable(false);
    mouse.setEditable(false);
    clicks.setEditable(false);
    KeyStatus.setEditable(false);

    text1.setBounds(135, 310, 150, 20);
    text2.setBounds(135, 330, 150, 20);
    text3.setBounds(135, 350, 150, 20);
    status.setBounds(15, 20, 240, 20);
    infomouse.setBounds(5,45,120,20);
    infoKeys.setBounds(5,90,120,20);
    KeyStatus.setBounds(15,115,240,85);
    test.setBounds(15,225,240,20);
    mouse.setBounds(15,70,100,20);
    infoclicks.setBounds(195, 45, 140, 20);
    clicks.setBounds(195, 70, 60, 20);

    item1.setBounds(5, 0, 120, 20);
    button1.setBounds(10, 310, 115, 20);
    button2.setBounds(10, 330, 115, 20);
    button3.setBounds(10, 350, 115, 20);
    sep1.setBounds(5, 305, 285, 10);

    sep1.setBackground(Color.BLACK);
    status.setBackground(Color.LIGHT_GRAY);

    button1.addActionListener(new button1list());
    button2.addActionListener(new button1list());
    button3.addActionListener(new button1list());

    button1.addMouseListener(new MouseList());
    button2.addMouseListener(new MouseList());
    button3.addMouseListener(new MouseList());
    getContentPane().addMouseListener(new MouseList());
    test.addKeyListener(new KeyList());
    this.addKeyListener(new KeyList());
    test.requestFocus();

    add(item1);
    add(button1);
    add(button2);
    add(button3);
    add(text1);
    add(text2);
    add(text3);
    add(status);
    add(infomouse);
    add(mouse);
    add(infoclicks);
    add(clicks);
    add(infoKeys);
    add(KeyStatus);
    add(test);
    add(sep1);

    setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    try{
    UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
    }catch (Exception e){System.out.println("Error");}
    SwingUtilities.updateComponentTreeUI(this);
    setSize(300, 400);
    setResizable(false);
    setVisible(true);
    test.setFocusable(true);
    test.setFocusTraversalKeysEnabled(false);
    setLocationRelativeTo(null);
}

public class button1list implements ActionListener {

    public void actionPerformed(ActionEvent e) {
        String buttonpressed = e.getActionCommand();
        if (buttonpressed.equals("Button1")) {
            text1.setText("just");
        } else if (buttonpressed.equals("Button2")) {
            text2.setText(text2.getText()+"testing ");
        } else if (buttonpressed.equals("Button3")) {
            text3.setText("this");
        } 
    }
}
    public class MouseList implements MouseListener{
        public void mouseEntered(MouseEvent e){
        if(e.getSource()==button1){
                status.setText("button 1 hovered");
            }
        else if(e.getSource()==button2){
                status.setText("button 2 hovered");
            }
        else if(e.getSource()==button3){
                status.setText("button 3 hovered");
            }
        }
        public void mouseExited(MouseEvent e){
                status.setText("");
        }
        public void mouseReleased(MouseEvent e){
            if(!status.getText().equals("")){
                status.replaceRange("", 0, 22);
            }
        }
        public void mousePressed(MouseEvent e){
            if(e.getSource()==button1){
                status.setText("button 1 being pressed");
            }
        else if(e.getSource()==button2){
                status.setText("button 2 being pressed");
            }
        else if(e.getSource()==button3){
                status.setText("button 3 being pressed");

            }
        }
        public void mouseClicked(MouseEvent e){
            clicknumber++;
            mouse.setText("mouse working");
            clicks.setText(String.valueOf(clicknumber));
      }
 }
    public class KeyList implements KeyListener{
        public void keyReleased(KeyEvent e){}
        public void keyPressed(KeyEvent e){
            KeyStatus.setText("");
            test.setText("");
            String full = e.paramString();
            String [] temp = null;
            temp = full.split(",");
            for(int i=0; i<7 ;i++){
            KeyStatus.append(temp[i] + "\n");
            }
            if(e.getKeyChar()=='h'){setVisible(false);
                test.requestFocus();
            }
            if(e.getKeyChar()=='s'){setVisible(true);}
        }
        public void keyTyped(KeyEvent e){}
    }

}

Answer 1

可见组件可以拥有键盘焦点，并接收键盘和其他输入事件，但不可见组件不能拥有焦点，也不能接收输入事件。当您使框架不可见时，它会停止接收输入事件，它的所有子组件也会停止接收输入事件，包括您要添加 KeyListener 的 test 组件。

要实现此功能，您必须有一个可见组件，并将键盘事件从该组件转发到不可见框架。或者更好的是，从已经可见的组件中调用 invisibelFrame.setVisible(true)。

或者，您也许可以找到其他方式来触发显示框架。例如，带有上下文菜单的系统托盘组件是隐藏和显示应用程序框架的常见模式(对于某些用户来说，在此过程中会引起很多烦恼!)

参见

• Sun Tutorial, how to use the System Tray