Name: clC74495 Date: 06/18/98


In JDK1.2 beta4 i&J on Windows NT,
GridBagLayout doesn't respect the preferred height of a JScrollPane if
the enclosing panel has a width less thant the preferred width of the JScrollPane.
If the JScrollPane happens to contain a JTable, this sizing problem
causes the JTable to throw exceptions.

Run the test code below and follow the instructions in the comment.
---------
import java.awt.*;
import java.awt.event.*;
import com.sun.java.swing.*;

/**
 * BugTest is a little program to demonstrate the incorrect sizing
 * behavior of JScrollPane controls inside GridBagLayout in JDK1.2beta4i & 4j.
 * The preferred size of the scrollable component is 400, 200, however,
 * when using GridBagLayout the preferred height is ignored if the actual
 * width is less than the preferred width. To compound the problem, if
 * a JTable is being displayed it throws exceptions due to the incorrect
 * sizing.
 *
 * To see the sizing but:
 * o run "java BugTest" - JTextArea using GridBagLayout.
 * o size window so width gets smaller than initial width. Do
 * it several times. Height gets really small.
 * o size window bigger than initial width. Things return to normal.
 *
 * To see the JTable throw exceptions:
 * o run "java BugTest -table"
 * o size window so width gets smaller than initial width. Do
 * it several times if needed.
 *
 * To see what SHOULD happen, run test with BorderLayout instead of
 * GridBagLayout:
 * o run "java BugTest -border" or "java BugTest -border -table"
 *
 * Email me questions if needed at ###@###.###
 */
public class BugTest
{
    public static void main( String[] args )
    {
        boolean useBorderLayout = false;
        boolean useTable = false;
        for ( int i = 0; i < args.length; i++ )
        {
            if ( args[i].equals( "-border" ) ) useBorderLayout = true;
            else if ( args[i].equals( "-table" ) ) useTable = true;
        }

        JFrame frame = new JFrame( "size me smaller to see sizing bug" );
        JComponent scrollableComponent = null;

        if ( useTable )
        {
            System.out.print("Using JTable");
            // try it with JTable, it throws exceptions when sizing
            scrollableComponent = new JTable(
                new Object[][] {
                    { "1", "2", "3", "4", "5", "6" },
                    { "1", "2", "3", "4", "5", "6" },
                    { "1", "2", "3", "4", "5", "6" },
                    { "1", "2", "3", "4", "5", "6" },
                    { "1", "2", "3", "4", "5", "6" },
                    { "1", "2", "3", "4", "5", "6" },
                    { "1", "2", "3", "4", "5", "6" },
                    { "1", "2", "3", "4", "5", "6" },
                    { "1", "2", "3", "4", "5", "6" },
                    { "1", "2", "3", "4", "5", "6" },
                    { "1", "2", "3", "4", "5", "6" }
                },
                new Object[] { "1", "2", "3", "4", "5", "6" }
            );
            ((JTable)scrollableComponent).setPreferredScrollableViewportSize( new
Dimension( 400, 200 ) );
        }
        else
        {
            System.out.print("Using JTextArea");
            // try it with JTextArea to just see sizing problem
            scrollableComponent = new JTextArea( "Should be 200 pixels in height" ) {
                public Dimension getPreferredScrollableViewportSize()
                {
                    return new Dimension( 400, 200 );
                }
            };
        }

        if ( useBorderLayout )
        {
            System.out.println(" in BorderLayout");
            // border layout test
            frame.getContentPane().setLayout( new BorderLayout() );
            frame.getContentPane().add( new JScrollPane( scrollableComponent ),
BorderLayout.NORTH );
        }
        else
        {
            System.out.println(" in GridBagLayout");
            // gridbag test
            frame.getContentPane().setLayout( new GridBagLayout() );
            GridBagConstraints gbc = new GridBagConstraints();
            gbc.gridx = 0;
            gbc.gridy = 0;
            gbc.weightx = 1;
            gbc.fill = gbc.HORIZONTAL;

            frame.getContentPane().add( new JScrollPane( scrollableComponent ), gbc );

            JPanel panel = new JPanel( new BorderLayout( 0, 5 ) );
            gbc.gridy++;
            gbc.weighty = 1;
            gbc.fill = gbc.BOTH;
            frame.getContentPane().add( panel, gbc );
        }

        // all tests
        frame.pack();
        frame.setVisible( true );
    }
}
(Review ID: 33835)
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