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

public class FlowLayoutTest extends JFrame
{
   private JButton leftBut, centerBut, rightBut;
   private Container c;
   private FlowLayout layout;
   
   public FlowLayoutTest()
   {
      super ("Flow Layout");
      layout = new FlowLayout(); // Make a new FlowLayout object
      c = getContentPane();      // Easy way to get space within the JFrame that won't overlap the title bar   
      c.setLayout(layout);       // Set the container's layout
   
      leftBut = new JButton ("Left");
      centerBut = new JButton ("Center");
      rightBut = new JButton ("Right");
   
      c.add(leftBut);   // Add the three buttons in left to right order...
      c.add(centerBut);
      c.add(rightBut);
   }
   
   public static void main (String args[])
   {
     FlowLayoutTest app = new FlowLayoutTest();
   
     app.addWindowListener( new WindowAdapter(){ public void windowClosing(WindowEvent e) { System.exit(0); } } );
     app.setSize (300,75);
     app.setVisible(true);
   }
}

Here's the result. Type the code in yourselves and see what it does when you manually shrink the window.

Note that the buttons don't do anything yet because we haven't written any event handlers for them. This is discussed in the section below, Handling Events.

import [...]

public class BorderLayoutTest extends JFrame implements ActionListener
{
   private JButton buttons[];
   private String names[] = {"Hide North", "Hide South", "Hide East", "Hide West", "Hide Center"};
   
   private Container c;
   private BorderLayout layout;
   
   public BorderLayoutTest()
   {
      super ("Border Layout");

      // Variables to specify the amount of space between the layout's regions
      int horizGapWidth=5, vertGapWidth=5;
   
      layout = new BorderLayout(horizGapWidth, vertGapWidth);
   
      c = getContentPane();
      c.setLayout(layout);
   
      buttons = new JButton[names.length];
   
      for (int b=0; b<names.length; b++)
      {
         buttons[b] = new JButton (names[b]);
         buttons[b].addActionListener(this);
      }
      // The order we add the buttons doesn;t matter for a border layout
      // because we explicitly specify the lcoation in which each is added.
      c.add(buttons[0], BorderLayout.NORTH);
      c.add(buttons[1], BorderLayout.SOUTH);
      c.add(buttons[2], BorderLayout.EAST);
      c.add(buttons[3], BorderLayout.WEST);
      c.add(buttons[4], BorderLayout.CENTER);
   }
   
   public void actionPerformed (ActionEvent e)
   {
      for (int b=0; b<buttons.length; b++)
      {
      if (e.getSource() == buttons[b]) { buttons[b].setVisible(false); }
      else { buttons[b].setVisible(true); }
   
      layout.layoutContainer( getContentPane() );
      }
   }
   
   public static void main (String args[])
   {
      BorderLayoutTest app = new BorderLayoutTest();
   
      app.addWindowListener( new WindowAdapter() { public void windowClosing(WindowEvent e) { System.exit(0); } } );
      app.setSize (300,200);
      app.setVisible(true);
   }
}

Here's the result. Type the code in yourselves. See what it does when you manually shrink the window or click on the buttons.

Now the buttons do something because we have attached an event handler to them. In this case we hide the button that has been clicked and show all the other buttons in our button array. Of course your program can do something much more interesting.

Note that our class implements the ActionListener interface. It provides a method actionPerformed() that catches the events of the buttons and does something in response.

import [...]

public class ComplexLayoutTest extends JFrame
{
   private JButton buttons[];
   private JPanel buttonPanel;
   
   public ComplexLayoutTest()
   {
      super ("Complex Layout with Panels");
   
      Container c;
      BorderLayout layout;
      int horizGapWidth=5, vertGapWidth=5;
   
      buttons = new JButton[3];
      buttonPanel = new JPanel();
   
      layout = new BorderLayout(horizGapWidth, vertGapWidth);
   
      c = getContentPane();
      c.setLayout(layout);
      c.setBackground(Color.blue);            // Set the background colour of this container
      buttonPanel.setLayout( new FlowLayout() );
   
      for (int b=0; b<3; b++)
      {
         buttons[b] = new JButton ("button " + (b+1));
         buttonPanel.add(buttons[b]);
      }
   
      c.add(buttonPanel, BorderLayout.SOUTH); // Add the JPanel to the South region of the container
   }
   
   public static void main (String args[])
   {
      ComplexLayoutTest app = new ComplexLayoutTest();
   
      app.addWindowListener( new WindowAdapter() { public void windowClosing(WindowEvent e) { System.exit(0); } } );
   
      app.setSize (300,200);
      app.setVisible(true);
   }
}

Here's the result. Type the code in yourselves and play around with the possibilities.

The JPanel sits within the South region of the BorderLayout that we have created. Its buttons are arranged using a FlowLayout. In this way we can create all kinds of useful layouts.

Note that the main container has been coloured blue.

import [...]

public class LabelTest extends JFrame
{
   private JLabel labelI, labelN, labelO;
   private JTextField text;
   private JPasswordField pass;
   private Container c;

   public LabelTest()
   {
      super ("Events, Labels and Text Entry");

      c = getContentPane();
      c.setLayout(new FlowLayout());
      c.setBackground(Color.white);
   
   // You can make labels with text and icons...
      Icon tent = new ImageIcon("Tent.GIF");
      labelI = new JLabel("A tent label with icon", tent, SwingConstants.LEFT);
      labelI.setToolTipText("A tent tool tip");
   
   // You can make labels with just text...
      labelN = new JLabel("A house label with no icon");
      labelN.setToolTipText("A house tool tip");
   
   // You make labels without passing parameters to the constructor...
      labelO = new JLabel();
      Icon tree = new ImageIcon("Tree.GIF");
      labelO.setIcon(tree);
      labelO.setText("A tree label with icon and text beneath");
      labelO.setToolTipText("A tree tool tip");
      labelO.setHorizontalTextPosition(SwingConstants.CENTER);
      labelO.setVerticalTextPosition(SwingConstants.BOTTOM);
   
   // You can build text and password fields with default text and of a specific size...
   text = new JTextField("Default text", 10);
   pass = new JPasswordField("Hidden", 5);
   
   // Set up an event handler to deal with the text entry boxes (see code below)
      TextFieldEventHandler handler = new TextFieldEventHandler();
   // Register the event handler for the text and pass GUI elements
      text.addActionListener(handler);
      pass.addActionListener(handler);
   
   // Add all of these to the JFrame...
      c.add(labelI); c.add(labelN); c.add(labelO);
      c.add(text); c.add(pass);
   }
   
   public static void main (String args[])
   {
      LabelTest app = new LabelTest();
      app.addWindowListener( new WindowAdapter() { public void windowClosing(WindowEvent e) { System.exit(0); } } );
      app.setSize (300,200);
      app.setVisible(true);
   }
   
   // The (inner) class for handling the events
   private class TextFieldEventHandler implements ActionListener
   {
      public void actionPerformed (ActionEvent e)
      {
         String s = "";
         // Determine what caused this event (returns a Component reference)
         if (e.getSource() == text)
         {
           s = "text entry box contents: " + e.getActionCommand();
         }
   
         else // if (e.getSource() == pass)
         {
           // Cast the Component ref. to a JPasswordField so that...
           JPasswordField pwd = (JPasswordField) e.getSource();
           // ...we can use its getPassword() method to extract the password
           s = "password entry box contents: " + new String( pwd.getPassword() );
         }
   
         JOptionPane.showMessageDialog(null, s);
      }
   }
}

Here's the result. Type it in and run it to see the event handler in action when you enter text into a box and hit <Return>

The first label has both an icon and text. The second just text. The third has an icon and the text is beneath it.

Note the tool tip that becomes visible when you move the mouse over the label.