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

public class Applet1 extends Applet implements ActionListener
{
    Label s;
    TextField input;
    Button btn;
    
    public void init()
    {
        s = new Label("pls input an alphabet:");
        input = new TextField(4);
        btn = new Button("confirm");
        add(s);
        add(input);
        add(btn);
        btn.addActionListener(this);
    }

    public void paint(Graphics g)
    {
        int n = 0;
        char c = ' ';

        String s = input.getText(); // read a String, not character

        if (!"".equals(s))
        {
            c = s.charAt(0); // take the first character
            n = (int) c;
        }

        if (n >= 97 && n <= 122)
        {
            n = 122 - (n - 97);
            c = (char) n;
            g.drawString("response alphabet：" + c, 200, 200);
        }
        else if (c >= 65 && c <= 90)
        {
            n = 90 - (n - 65);
            c = (char) n;
            g.drawString("response alphabet：" + c, 200, 200);
        }
    }

    public void actionPerformed(ActionEvent e)
    {
        if (e.getSource() == btn)
        {
            repaint();
        }
    }
}