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

/* ListDemo illustrates the use of JLabels, JTextFields,
 * JScrollPanes and JLists.
 * 
 * Written by: Stuart Hansen
 * September 8, 2008
 */
public class ListDemo extends JFrame
{
   // These elements form the GUI of the application
   private JLabel enterLabel;    
   private JTextField enterField;
   private JScrollPane listPane;
   private JList list;     
   
   // The constructor 
   public ListDemo () {
      super ("List Demo");
      enterLabel = new JLabel();    
      enterField = new JTextField();
      
      // The DefaultListModel on the next line gives us the
      // ability to add to the list
      list = new JList(new DefaultListModel()); 

      // The list is added to a JScrollPane, so that we may
      // view lists larger than the display
      listPane = new JScrollPane(list);
      
      // setup the contentPane to use absolute coordinates
      Container contentPane = getContentPane();
      contentPane.setLayout(null);
      
      // initialize and add the components to the GUI
      enterLabel.setText("Enter some text");
      enterLabel.setSize(100, 30);
      enterLabel.setLocation(20, 20);
      contentPane.add(enterLabel);
      
      enterField.setSize(100, 20);
      enterField.setLocation(120 ,25);
      contentPane.add(enterField);
      enterField.addActionListener(new InputListener());
      
      listPane.setSize(100, 200);
      listPane.setLocation(20, 60);
      contentPane.add(listPane);
     
      // Set the windows size and close operation
      setSize(300, 300);
      setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
     
      // display the application window
      setVisible(true);
   }
   
   // The ActionListener for the JTextField
   // The event if fired when enter is pressed
   // The text is added to the list
   private class InputListener implements ActionListener
   {
      public void actionPerformed(ActionEvent e)
      {
         String text = enterField.getText();
         DefaultListModel model = ((DefaultListModel)(list.getModel()));
         if (!text.equals(""))
         {
            model.addElement(text) ;
            enterField.setText("");
         }
      }
   }
   
   // a very simple main program
   public static void main (String args[]) {
      new ListDemo();
   }
}