import java.awt.BorderLayout;
import java.awt.event.ActionListener;
import java.awt.event.ActionEvent;
import java.awt.Color;
import javax.swing.JPanel;
import javax.swing.JFrame;
import javax.swing.JButton;
import javax.swing.JLabel;

public class Ajout extends JFrame {
    
    Ajout() {  
	super("ajout");
	final JButton bouton = new JButton("Ajouter");
	setLayout(new BorderLayout(5, 5));
	add(bouton, BorderLayout.NORTH);
	bouton.addActionListener(new ActionListener() {
		public void actionPerformed(ActionEvent e) {
		    JLabel texte = new JLabel("bonjour");
		    texte.setBackground(Color.YELLOW);
		    texte.setOpaque(true);
		    add(texte, BorderLayout.SOUTH);
		    validate();
		}
	    });
	setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
	setLocation(300, 400);
	setSize(200, 100);
	setVisible(true);
    }
}

class EssaiAjout {    
    public static void main(String[] arg) {
	new Ajout();
    }
}