Ecco il codice giusto:
codice:
 
package Applet;
import java.awt.*; 
import java.applet.*; 
import java.awt.event.*; 

public class Prova extends Applet implements ActionListener { 
public TextField t;   

public void init() {    
Panel b=new Panel(); 
b.setSize(50,50); 
Button click=new Button("Cliccami");
t=new TextField("Cancellami"); 
add(click); 
add(t); 
click.addActionListener(this); 
repaint(); 
} 

public void actionPerformed(ActionEvent e) { 
t.setText("Mi hai cancellato"); 
repaint();} 

public void paint(Graphics g) { 
}