gridlayoutdemo.java

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// Fig. 13.26: GridLayoutDemo.java
// Demonstrating GridLayout.
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;

public class GridLayoutDemo extends JFrame implements ActionListener {
   private JButton buttons[];
   private final String names[] = 
      { "one", "two", "three", "four", "five", "six" };
   private boolean toggle = true;
   private Container container;
   private GridLayout grid1, grid2;

   // set up GUI
   public GridLayoutDemo()
   {
      super( "GridLayout Demo" );

      // set up layouts
      grid1 = new GridLayout( 2, 3, 5, 5 );
      grid2 = new GridLayout( 3, 2 );

      // get content pane and set its layout
      container = getContentPane();
      container.setLayout( grid1 );

      // create and add buttons
      buttons = new JButton[ names.length ];

      for ( int count = 0; count < names.length; count++ ) {
         buttons[ count ] = new JButton( names[ count ] );
         buttons[ count ].addActionListener( this );
         container.add( buttons[ count ] );
      }

      setSize( 300, 150 );
      setVisible( true );

   } // end constructor GridLayoutDemo

   // handle button events by toggling between layouts
   public void actionPerformed( ActionEvent event )
   { 
      if ( toggle )
         container.setLayout( grid2 );
      else
         container.setLayout( grid1 );

      toggle = !toggle;   // set toggle to opposite value
      container.validate();
   }

   public static void main( String args[] )
   {
      GridLayoutDemo application = new GridLayoutDemo();
      application.setDefaultCloseOperation( JFrame.EXIT_ON_CLOSE );
   } 

} // end class GridLayoutDemo