Custom JTable colum renderer eat up CPU resources

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Michael - 23 Mar 2004 01:43 GMT

My following codes causes the CPU usage to 100% all the time:

CustomTableHeaderRenderer renderer = new CustomTableHeaderRenderer();

TableColumn col1 = this.getColumnModel().getColumn( 0 );
TableColumn col2 = this.getColumnModel().getColumn( 1 );
col1.setHeaderRenderer( renderer );
col2.setHeaderRenderer( renderer );
this.setDefaultRenderer( this.getClass(), renderer );

What could be the reason for that? And how do I go about solving it?

TIA.

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Christian Kaufhold - 23 Mar 2004 13:37 GMT

> My following codes causes the CPU usage to 100% all the time:
>
[quoted text clipped - 7 lines]
>
> What could be the reason for that? And how do I go about solving it?

What is CustomTableHeaderRenderer (code)? Why is it used for normal
cells as well? Why does your TableModel contain (presumably) JTables?

Christian

Signature

And in short, I was afraid.

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Michael - 31 Mar 2004 05:52 GMT

> > My following codes causes the CPU usage to 100% all the time:
> >
[quoted text clipped - 12 lines]
>
> Christian

Hi Christian,

My CustomTableHeaderRenderer() does the following:

public class CustomTableHeaderRenderer extends JLabel implements
TableCellRenderer {
public Component getTableCellRendererComponent( JTable table,
Object value,
boolean isSelected, boolean hasFocus, int rowIndex, int
vColIndex ) {
// 'value' is column header value of column 'vColIndex'
// rowIndex is always -1
// isSelected is always false
// hasFocus is always false

// Configure the component with the specified value
setText( value.toString() );

// Set tool tip if desired
// setToolTipText( ( String ) value );

JTableHeader header = table.getTableHeader();
// header.setBackground( HEADER_COLOR );

// Disable the column-swapping feature
header.setReorderingAllowed( false );
header.setFont( new Font( "Tahoma", Font.BOLD, 12 ) );
// header.setResizingAllowed( false );

// This somehow removed the border lines
// setBorder( UIManager.getBorder(
"Table.focusCellHighlightBorder" ) );

if ( table.isCellEditable( rowIndex, vColIndex ) ) {
setForeground( UIManager.getColor(
"Table.focusCellForeground" ) );
setBackground( UIManager.getColor(
"Table.focusCellBackground" ) );
}

// this.revalidate();

// Since the renderer is a component, return itself
return this;
}

Yes, my TableModel contains JTable.

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Christian Kaufhold - 31 Mar 2004 15:02 GMT

> public class CustomTableHeaderRenderer extends JLabel implements
> TableCellRenderer {

> public Component getTableCellRendererComponent( JTable table,
> Object value,
[quoted text clipped - 17 lines]
> header.setReorderingAllowed( false );
> header.setFont( new Font( "Tahoma", Font.BOLD, 12 ) );

These lines have no business here. Move them to where the table/header
is created. In the renderer code, pick up the settings of the header, or
it won't have any effect:

setFont(header.getFont());

(and also,

setEnabled(header.isEnabled());
setComponentOrientation(header.getComponentOrientation());
)

> if ( table.isCellEditable( rowIndex, vColIndex ) ) {

> setForeground( UIManager.getColor(
> "Table.focusCellForeground" ) );
> setBackground( UIManager.getColor(
> "Table.focusCellBackground" ) );
> }

This is pointless and wrong for a header renderer.
Header cells are never editable.

Christian

Signature

http://www.chka.de/swing/table/faq.html

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Michael - 01 Apr 2004 02:28 GMT

>
> > public class CustomTableHeaderRenderer extends JLabel implements
[quoted text clipped - 45 lines]
>
> Christian

Thanks, but how do I disable column swapping?

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Christian Kaufhold - 01 Apr 2004 12:11 GMT

> Thanks, but how do I disable column swapping?

JTable t = new JTable(...);

t.getTableHeader().setReorderingAllowed(false);

Christian

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Custom JTable colum renderer eat up CPU resources

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