Gestion des evenements JAva

import java.awt.BorderLayout;
import java.awt.GridLayout;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JTextArea;

public class Test1
{
public static void main(String...args)
{                
    JFrame frame = new JFrame();
    
    JTextArea resultat = new JTextArea("-1234.56789");
    resultat.setEditable(false);
    frame.add(resultat,BorderLayout.NORTH);
    
    JPanel chiffres = new JPanel();
    chiffres.setLayout(new GridLayout(4,3));
    for (char c : "7894561230".toCharArray())
        chiffres.add(new JButton(String.valueOf(c)));
    frame.add(chiffres,BorderLayout.WEST);

    JPanel operateurs = new JPanel();
    operateurs.setLayout(new GridLayout(3,2));
    for (char c : "x/+-.=".toCharArray())
        operateurs.add(new JButton(String.valueOf(c)));
    frame.add(operateurs,BorderLayout.EAST);
    
    JPanel operateurs2 = new JPanel();
    operateurs2.setLayout(new GridLayout(1,4));
    for (char c : "%^\u221a\u03c0".toCharArray())
        operateurs2.add(new JButton(String.valueOf(c)));
    frame.add(operateurs2,BorderLayout.SOUTH);
        
    frame.pack();
    frame.setVisible(true);
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
}
}