GridLayout Demo

// Fig. 14.44: GridLayoutDemo.java
// Testing GridLayoutFrame.

import java.awt.GridLayout;
import java.awt.Container;
import java.awt.event.ActionListener;
import java.awt.event.ActionEvent;
import javax.swing.JFrame;
import javax.swing.JButton;

class GridLayoutFrame extends JFrame implements ActionListener 
{
   private JButton[] buttons; // array of buttons
   private static final String[] names = 
      { "one", "two", "three", "four", "five", "six" };
   private boolean toggle = true; // toggle between two layouts
   private Container container; // frame container
   private GridLayout gridLayout1; // first gridlayout
   private GridLayout gridLayout2; // second gridlayout

   // no-argument constructor
   public GridLayoutFrame()
   {
      super( "GridLayout Demo" );
      gridLayout1 = new GridLayout( 2, 3, 5, 5 ); // 2 by 3; gaps of 5
      gridLayout2 = new GridLayout( 3, 2 ); // 3 by 2; no gaps
      container = getContentPane(); // get content pane
      setLayout( gridLayout1 ); // set JFrame layout
      buttons = new JButton[ names.length ]; // create array of JButtons

      for ( int count = 0; count < names.length; count++ )
      {
         buttons[ count ] = new JButton( names[ count ] );
         buttons[ count ].addActionListener( this ); // register listener
         add( buttons[ count ] ); // add button to JFrame
      } // end for
   } // end GridLayoutFrame constructor

   // handle button events by toggling between layouts
   public void actionPerformed( ActionEvent event )
   { 
      if ( toggle )
         container.setLayout( gridLayout2 ); // set layout to second
      else
         container.setLayout( gridLayout1 ); // set layout to first

      toggle = !toggle; // set toggle to opposite value
      container.validate(); // re-lay out container
   } // end method actionPerformed
} // end class GridLayoutFrame


public class GridLayoutDemo 
{
   public static void main( String[] args )
   { 
      GridLayoutFrame gridLayoutFrame = new GridLayoutFrame(); 
      gridLayoutFrame.setDefaultCloseOperation( JFrame.EXIT_ON_CLOSE );
      gridLayoutFrame.setSize( 300, 200 ); // set frame size
      gridLayoutFrame.setVisible( true ); // display frame
   } // end main
} // end class GridLayoutDemo