for (int row = 0; row < rowCount; row++) {
for (int column = 0; column < columnCount; column++) {
Number lvalue;
Number uvalue;
if (interval) {
final IntervalCategoryDataset icd = (IntervalCategoryDataset) dataset;
lvalue = icd.getStartValue(row, column);
uvalue = icd.getEndValue(row, column);
} else {
lvalue = dataset.getValue(row, column);
uvalue = lvalue;
}
if (lvalue != null) {