Java removeActionListener怎么用

[呆维]

ActionListener closeListener;
JButton closeButton=new JButton();

closeListener = new
ActionListener()
{
public void actionPerformed(ActionEvent event)
{
closeButton.removeActionListener(closeListener); /////
dispose(); ///////
}
};
closeButton.addActionListener(closeListener);
这段代码实现功能是关闭所有窗口,谁能解释一下.
我把带////的两行注释掉之后仍旧能够实现该功能,这又怎么解释