Question

I have a JTable component in my GUI which displays psuedocode of an algorithm. I want to highlight the current line of execution by changing the background of a particular cell and then changing the cell beneath and so on.

Right now my code changes the backgrounds on all cells in my JTable as pictured below:

The code I am using to archive this current state is as below:

class CustomRenderer extends DefaultTableCellRenderer 
{
    @Override
    public Component getTableCellRendererComponent(JTable table, Object value, boolean isSelected, boolean hasFocus, int row, int column)
    {
            JLabel d = (JLabel) super.getTableCellRendererComponent(table, value, isSelected, hasFocus, row, column);
            if((row == 0) && (column == 0))
                d.setBackground(new java.awt.Color(255, 72, 72));
            return d;
        }
    }

I then call jTable2.setDefaultRenderer(String.class, new CustomRenderer()); in my constructor.

I assume that:

• This method is being called on every String type table cell.
• That this would only change the colour of the cell at position (0,0)

How do I fix my code so that only cell (0,0) is coloured?

Answer 1

Add an else clause to your if:

if ((row == 0) && (column == 0)) {
    d.setBackground(new java.awt.Color(255, 72, 72));
}
else {
    d.setBackground(Color.WHITE);
}

Remember that the same renderer instance is used to paint all the cells.