OÙ EN SUIS JE? NUMÉROTATION DES LIGNES D'UN JTEXTAREA!

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;


public class Console extends JFrame implements ActionListener{
	
    JTextField input;
    JTextArea console;
    JTextArea nbr_ligne;
    JPanel main_txt;
    JScrollPane scrollPane;
    
	public Console(){
		setTitle("Console");
		setBounds(0,0,500,300);
		getContentPane().setLayout(new BorderLayout());
		setDefaultCloseOperation(EXIT_ON_CLOSE);
			{
			input = new JTextField();
			input.addActionListener(this);
			}
			{ 
			console = new JTextArea();
			console.setEditable(false);
			}
			{
			nbr_ligne = new JTextArea();
			nbr_ligne.setEditable(false);
			nbr_ligne .setBackground(new Color(0, 128, 128));
    		nbr_ligne.setForeground(Color.white);
			}	
			{
			main_txt = new JPanel();
			main_txt.setLayout(new BorderLayout());
			main_txt.add("West", nbr_ligne);
			main_txt.add("Center", console);
			scrollPane = new JScrollPane(main_txt, JScrollPane.VERTICAL_SCROLLBAR_ALWAYS, JScrollPane.HORIZONTAL_SCROLLBAR_AS_NEEDED);
			}
		getContentPane().add("North",input);	
		getContentPane().add("Center",scrollPane);
	}
	
	public void actionPerformed(ActionEvent evt) {
        String text = input.getText();
	        {
	    	int j = nbr_ligne.getLineCount();
	    	nbr_ligne.append(j+"\n");
	    	}
	    	{
	    	console.append(" > "+text+"\n");
	    	}
	        {
	        input.selectAll();
	    	}
    }
	
	public static void main(String[] args){
		try{UIManager.setLookAndFeel("com.sun.java.swing.plaf.windows.WindowsLookAndFeel");}catch (Exception e){}
		Console index = new Console();
		index.setVisible(true);	
	}
}