JScrollPane : Java Glossary

Tips

• Add the contents to be scrolled in the JScrollPane constructor. Don’t add it later the way you do with ScrollPane. For some reason, if you add it later, all you see then is a blank panel, even though all the code appears to paint normally. You can however add/change it later with setViewportView.
• You can freeze a non-vertically-scrolling header with setColumnHeader or setColumnHeaderView just like a spreadsheet. There are analogous features for non-horizontally-scrolling row headers.
• You can control what is visible with by getting the horizontal or vertical JScrollBar and using setValue.
• JScrollPane lets you independently control whether there are vertical or horizontal scroll bars, unlike AWT ScrollPane which requires both to be set the same way.

Making Visible

// Make sure most recent material visible, at the bottom.
// G O T C H A !
// Use invokeLater to give time for text to render
// after a JTextArea.setText before we process the setValue,
// otherwise the setValue will be effectively ignored.
// Must run on Swing thread.
jTextAreaBeingScrolled.setText( newText );
final JScrollBar v = scroller.getVerticalScrollBar();
v.setValue( v.getMaximum() );  /* Use setMinimum for making top visible */

// make part of a JTable visible in the scroll region.
// Must run on Swing thread.
final Rectangle r = jTable.getCellRect( rowIndex, colIndex, true );
if ( r != null )
   {
   jTable.scrollRectToVisible( r );
   }

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