How to handle duplicate columnheaders in tablecellrenderer?

Question

Hi guys i have the following issue in my program. I have several tablecellrenderers which are applied by column. The problem is if a column appears two times in my table the cellrenderer won't work, and leaves both columns unformatted. I am also not able to change the column names because my customer has a specific idea of how this table should look like

I asked google, the stackoverflow search but i can't find any solution for this.

Do you know a workaround for this?

Thanks in advance

The Lines where i apply the cellrenderer

for(int i=0;i<(columnnames.length-anz_col);i++){
   //Berechnung einmalig durchführen
   actcol=i+anz_col;
   //CellFormater
   tbl_patchstand.getColumn(columnnames[actcol]).setCellRenderer(new PatchstandCellRenderer(tbl_patchstand.getDefaultRenderer(Object.class), actcol, maxfpatches[i]));
   tbl_patchstand.getColumn(columnnames[actcol]).setCellRenderer(new PatchstandCellRenderer(tbl_patchstand.getDefaultRenderer(Double.class), actcol, maxfpatches[i]));
   tbl_patchstand.getColumn(columnnames[actcol]).setCellRenderer(new PatchstandCellRenderer(tbl_patchstand.getDefaultRenderer(Integer.class), actcol, maxfpatches[i]));
}

The Cellrenderer itself:

public class PatchstandCellRenderer extends DefaultTableCellRenderer {
 /**
   * 
      */
    private int maxval,col;
    private double oldval,newval;

    public PatchstandCellRenderer(TableCellRenderer cellRenderer, int col, int maxval) {
        super();
        this.maxval=maxval;
    this.col=col;
}

    public Component getTableCellRendererComponent(JTable table, Object value, boolean isSelected, boolean hasFocus, int row, int column){  
        Component c = super.getTableCellRendererComponent(table, value, isSelected, hasFocus, row, column);
        if((column==col) && value!=null && (!((String)value).trim().equals("-")) && (!((String)value).trim().equals(""))){
            //Umrechnen Wert auf Range
            oldval=Double.parseDouble((String) value);
            newval=(oldval)/(maxval);
            c.setBackground(GetColor.getColor(newval));
        }
        else
            c.setBackground(Color.WHITE);
        return c;  
    }  
}

The Cellrenderer gets a maxvalue of this column which is calculated before the cellrenderer will be applied. This maxvalue is used to get an color range from o to max in java hue color scheme.

Answer 1

Use column model to set a renderer for your column.

Instead of

tbl_patchstand.getColumn(columnnames[actcol])

use

tbl_patchstand.getColumnModel().getColumn(actcol)

Index must be unique for each column.
This should solve your problems.