Question

I have a JTable where i enter some values. This is the listener function to know if it has been made any change at the values, so i can update them. Values must have the format indicated (#.###), so I’m doing this fix to round the float to 3 decimal places if the client enter more than 3.

    private class CambioTablaPretratamientoListener implements TableModelListener{
    public void tableChanged(TableModelEvent e){
        try{
            if(enviarDatosADispositivo){
                TableModel model = (TableModel)e.getSource();
                float value = Float.parseFloat((String)model.getValueAt(e.getLastRow(), 1));
                DecimalFormat dec = new DecimalFormat("#.###");
                String aux = dec.format(value);
                if(model.getValueAt(e.getLastRow(), 1).equals(aux))
                    return;
                else
                    model.setValueAt(aux, e.getLastRow(), 1);
                value = Float.parseFloat(aux);

                String nombreAtributo = (String)model.getValueAt(e.getLastRow(), 0);

                nodoAModificar.setPretratamientUserParameter(nombreAtributo, value);     
            }
        }catch(BusinessException ex){
            ex.printStackTrace();
        }
    }
}

Code seems to work at first, because it rounds and the number appears in the table, but the value is not getting updated. I guess I’m doing something wrong with the DecimalFormat, because if I leave the function like this one, it works:

    private class CambioTablaPretratamientoListener implements TableModelListener{
    public void tableChanged(TableModelEvent e){
        try{
            if(enviarDatosADispositivo){
                TableModel model = (TableModel)e.getSource();
                float value = Float.parseFloat((String)model.getValueAt(e.getLastRow(), 1));
                String nombreAtributo = (String)model.getValueAt(e.getLastRow(), 0);

                nodoAModificar.setPretratamientUserParameter(nombreAtributo, value);     
            }
        }catch(BusinessException ex){
            ex.printStackTrace();
        }
    }
}

And finall

Answer 1

If you use BigDecimal, you could actually truncate the numbers, instead of trying to use Float’s (lack of) precision.