jcombox.txt

组合框(JComboBox)应用实例

import java.awt.*;	 // Java core packages
import java.awt.event.*;	 // Java core packages
import javax.swing.*;	 // Java extension packages

public class ComboBoxTest extends JFrame
{
    private JComboBox comboBox;
    private JLabel label;
    private String names[] ={ "bug1.gif", "bug2.gif",  
                                                "travelbug.gif", "buganim.gif" };
    private Icon icons[] = new ImageIcon[4];
    
    public ComboBoxTest()  // set up GUI
    {
        super( "Testing JComboBox" );
        for (int i= 0; i< 4; i++)
            icons[i]= new ImageIcon( names[ i ] );

       Container container = getContentPane();
        container.setLayout( new FlowLayout() );      
// set up JComboBox and register its event handler
        comboBox = new JComboBox( names );
        comboBox.setMaximumRowCount( 3 );
        container.add( comboBox );
        comboBox.addItemListener(new ItemListener() 
            {// anonymous inner class to handle JComboBox events
                // handle JComboBox event
                public void itemStateChanged( ItemEvent event )
                {
                    // determine whether check box selected
                    if ( event.getStateChange() == ItemEvent.SELECTED )
                        label.setIcon( icons[ comboBox.getSelectedIndex() ] );
                }
            }  // end anonymous inner class
        ); // end call to addItemListener
        
        // set up JLabel to display ImageIcons
        label = new JLabel( icons[ 0 ] );
        container.add( label );
setSize( 250, 100 );
        setVisible( true );
    } // End of constructor: ComboBoxTest()
    
    public static void main( String args[] )
    { 
        ComboBoxTest app = new ComboBoxTest();
        app.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE );
    }
}  // end class ComboBoxTest