Name: krT82822 Date: 10/22/99


There is a flaw in the logic determining the preferred or minimum layout size when using FlowLayout.
If the first component is hidden, the logic adds an extra HGAP
to the returned width.

Sample code ------------------------------------------------
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;

public class FlowButtonTest extends JButton implements ActionListener
{
    static JButton button1;
    static JButton button2;
    static JFrame fr;
    static int mode = 0;

    public static void main( String[] args )
    {
        fr = new JFrame( "Flow" );
        Container c = fr.getContentPane();
        // Specify an extra large HGAP to highlight the problem
        c.setLayout( new FlowLayout( FlowLayout.LEFT , 50 , 5 ) );

        button1 = new FlowButtonTest( "Button 1" );
        c.add( button1 );
        button2 = new FlowButtonTest( "Button 2" );
        c.add( button2 );

        fr.pack();
        fr.setDefaultCloseOperation( JFrame.EXIT_ON_CLOSE );
        fr.setVisible( true );
    }

    public Flow( String text )
    {
        super( text );
        addActionListener( this );
    }

    public void actionPerformed( ActionEvent evt )
    {
        mode = ( mode + 1 ) % 3;

        switch( mode ){
          case 0:
            button1.setVisible( true );
            button2.setVisible( true );
            break;
          case 1:
            button1.setVisible( true );
            button2.setVisible( false );
            break;
          case 2:
            button1.setVisible( false );
            button2.setVisible( true );
            break;
        }

        fr.pack();
    }
}
End of Sample code -----------------------------------------

When run the program will show a frame with two buttons. When either button is pressed the program will cycle through (a)showing both buttons, (b)showing button 1 and (c)showing button 2.
When button 1 is hidden there is an extra HGAP visibly added to the width.

This produces no errors or exceptions.

java -version =>
java version "1.3beta"
Java(TM) 2 Runtime Environment, Standard Edition (build 1.3beta-O)
Java(TM) HotSpot Client VM (build 1.3beta-O, mixed mode)

java -fullversion =>
java full version "1.3beta-O"

This also occurs with JDK 1.2.2
(Review ID: 96871)
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