为什么不在框架上绘制字符串？

Question

我已经尝试使用KeyListener interface在我的框架上绘制一个字符串，这样每当我在键盘上点击一个可键入的键时，它应该出现在帧上，但即使没有错误它也不起作用。

有人能说出这是什么错误吗？

以下是我的代码：

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;

class KeyevntFrame2 extends Frame {
    Button b = new Button("ok");
    Button b1 = new Button("hey");
    char ch;
    String s = "";

    public KeyevntFrame2() {
        setTitle("understand key events");
        setSize(800, 600);
        addKeyListener(new KeyHandler());
        setFont(new Font("Arial", Font.PLAIN, 35));
        setForeground(Color.BLACK);
        add(b);
        add(b1);

        b.setBounds(200, 200, 100, 100);
        b1.setBounds(200, 700, 100, 100);
        setLayout(null);

        b.addActionListener(new KeyHandler());
        b1.addActionListener(new KeyHandler());
    }

    class KeyHandler implements KeyListener, ActionListener {
        public void keyPressed(KeyEvent e) {
            ch = e.getKeyChar();
            s = s + ch;
            repaint();
        }

        public void keyReleased(KeyEvent e) {
        }

        public void keyTyped(KeyEvent e) {

        }

        public void paint(Graphics g) {
            g.drawString(s, 300, 200);
            g.setFont(new Font("Arial", Font.PLAIN, 35));
        }

        public void actionPerformed(ActionEvent e) {
            JOptionPane.showMessageDialog(b1, "thank you for using java");
        }
    }

    public static void main(String a[]) {
        KeyevntFrame2 f = new KeyevntFrame2();
        f.setVisible(true);
    }
}