Ejemplo JAVA : ActionListener Button actionPerformed ActionEvent

import java.applet.Applet;
import java.awt.*;
import java.awt.event.*;
/*
<APPLET
    CODE=areadetexto.class
    WIDTH=200
    HEIGHT=200 >
</APPLET>
*/
public class areadetexto extends Applet implements ActionListener {
    TextArea textarea1;
    Button button1;
    public void init(){
        textarea1 = new TextArea("", 10, 20, TextArea.SCROLLBARS_BOTH);
        add(textarea1);
        button1 = new Button("¡Haga clic aquí!");
        add(button1);
        button1.addActionListener(this);
    }
    public void actionPerformed (ActionEvent e)
    {
        String msg = "¡Hola desde Java!";
        if(e.getSource() == button1){
            textarea1.insert(msg, 0);
        }
    }
}