Ocultar TextFields

import java.awt.Container;

import java.awt.GridLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;


import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JTextField;

public class Tela extends JFrame 
{
	private JTextField fields[];
	private JButton button;
	private GridLayout layout;
	
	public Tela()
	{
		super( " Tela " );
		
		layout = new GridLayout( 5 ,2 ,4 ,4);
		
		Container container = getContentPane();
		container.setLayout( layout );
		
		
		fields = new JTextField[10];
		
		for (int i = 0; i < fields.length; i++) 
		{
			fields[ i ] = new JTextField( 10 );
			container.add( fields [ i ] );
		}
		
		for (int i = 1; i < fields.length; i++) 
		{
			fields[ i ].setVisible( false );
		}
		
		TrataEvento evento = new TrataEvento();
		
		fields[0].addActionListener( evento );
		
		setVisible( true );
		setSize( 400,200 );
	}
	
	private class TrataEvento implements ActionListener
	{
		public void actionPerformed( ActionEvent event )
		{
			if( event.getSource() == fields[ 0 ])
			{
				int numFieds = Integer.parseInt( fields[0].getText());
				
				for (int i = 1; i < numFieds; i++) 
				{
					fields[ i ].setVisible( true );
				}
			}
		}
	}
	
}

import javax.swing.JFrame;

public class Testa 
{
	public static void main(String[] args) 
	{
		Tela tela = new Tela();
		tela.setDefaultCloseOperation( JFrame.EXIT_ON_CLOSE );
	}
}