Spiegazioni su JRadioButton

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

import javax.swing.ButtonGroup;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JRadioButton;

public class ProvaJRadioButton extends JFrame
{
	public ProvaJRadioButton() 
	{
		super("Prova");
		setSize(150, 150);
		setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
		
		JPanel panel = new JPanel();
		add(panel);
		
		final JRadioButton bott1 = new JRadioButton("prova 1 ");
		final JRadioButton bott2 = new JRadioButton("prova 2");
		
		ButtonGroup gruppo = new ButtonGroup();
		gruppo.add(bott1);
		gruppo.add(bott2);
		
		panel.add(bott1);
		panel.add(bott2);
		
		final JButton bottone = new JButton("Prova");
		panel.add(bottone);
		
		class ActionListenerBotton implements ActionListener
		{
			public void actionPerformed(ActionEvent event)
			{
				ActionListener scelta = null;
				if(bott1.isSelected())
					scelta = new ActionLister1();
				else if(bott2.isSelected())
					scelta = new ActionLister2();
				bottone.addActionListener(scelta);
			}
		}
		
		bottone.addActionListener(new ActionListenerBotton());

		setVisible(true);
	}
	
	class ActionLister1 implements ActionListener
	{
		public void actionPerformed(ActionEvent event)
		{
			JFrame frame = new JFrame("Prova 1");
			frame.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
			frame.setSize(150, 100);
			frame.setVisible(true);
		}
	}
	
	class ActionLister2 implements ActionListener
	{
		public void actionPerformed(ActionEvent event)
		{
			JFrame frame = new JFrame("Prova 2");
			frame.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
			frame.setSize(150, 100);
			frame.setVisible(true);
		}
	}
}

class test
{
	public static void main(String arg[])
	{
		ProvaJRadioButton prova = new ProvaJRadioButton();
	}
}