java - 该程序的 KeyAdapter 部分出错

Question

该程序编译执行成功。但是当我输入一些字符时，框架不会显示其中的这些字符。为什么 ？错误是什么？

import java.awt.*;
import java.awt.event.*;
import java.applet.*;

class frameadapter extends WindowAdapter
{
    newframe newthis;

    public frameadapter(newframe n)
    {
        newthis=n;
    }
    public void windowClosing(WindowEvent we)
    {
        newthis.setVisible(false);
        System.exit(0);
    }

}


class keyadapter extends KeyAdapter
{
    newframe keythis;
    public keyadapter(newframe n1)
    {
        keythis=n1;
    }

    public void KeyTyped(KeyEvent ke)
    {
        keythis.keymsg+=ke.getKeyChar();
        System.out.println(keythis.keymsg);
        keythis.repaint();
    }   
}




public class newframe extends Frame implements MouseListener
{
    int mouseX;
    int mouseY;
    String keymsg="This is a Test";
    String msg="";
    public newframe()
    {
        addKeyListener(new keyadapter(this));
        addWindowListener(new frameadapter(this));
        addMouseListener(this);
        this.setSize(600,600);
        this.setVisible(true);
    }

    public void paint(Graphics g)
    {
        g.drawString(keymsg,100,100);
        g.drawString(msg, 500, 200);
    }


    public void mouseClicked(MouseEvent e) {
        mouseX=this.getX();
        mouseY=this.getY();
        msg="MOUSE CLICKED AT";
        repaint();
    }


    public void mousePressed(MouseEvent e) {
        mouseX=this.getX();
        mouseY=this.getY();
        msg="MOUSE PRESSED AT";
        repaint();
    }

    public void mouseReleased(MouseEvent e) {
        mouseX=this.getX();
        mouseY=this.getY();
        msg="MOUSE RELEASED AT";
        this.setForeground(Color.WHITE);
        this.setBackground(Color.BLACK);
        repaint();
    }

    public void mouseEntered(MouseEvent e) {
        mouseX=this.getX();
        mouseY=this.getY();
        msg="MOUSE ENTERED AT";
        repaint();
    }


    public void mouseExited(MouseEvent e) {
        mouseX=this.getX();
        mouseY=this.getY();
        msg="MOUSE EXITED AT";
        repaint();
    }

    public static void main(String args[])    
    {
        newframe n=new newframe();
    }
}

我认为错误出现在 Keyadapter 类中。但无法找到解决方案。

Answer 1

1. KeyListener 仅当其注册的组件可聚焦且具有键盘焦点时才响应按键事件
2. Frame 不可聚焦，从关键事件的角度来看，这使得它无法(但默认)接收关键事件通知...

除非您迫切需要这样做，否则我建议不要使用 Frame，而是使用 JFrame 作为您的窗口，因为 AWT 已经有 15 年以上的历史了已过时，一般不再使用。看看Creating a GUI With JFC/Swing了解更多详情

相反，从 JPanel 开始，重写它的 paintComponent 方法，以便在那里执行自定义绘制。看看Performing Custom Painting了解更多详情。

使用key bindings API登记针对专家组的关键行动。这将允许您定义面板接收关键事件通知所需的焦点级别