Creating a Text Field
When the user hits RETURN, the text field fires an action event. 

 
 JTextField textfield = 
   new JTextField("Initial Text");
 textfield.addActionListener(new MyActionListener());
     
 class MyActionListener implements ActionListener {
     public void actionPerformed(ActionEvent evt) {
         JTextField textfield = 
           (JTextField)evt.getSource();
         process(textfield.getText());
     }
 }