int displayNum = (j - firstDay + 1);
if (j < firstDay || displayNum > numOfDays) {
grid.getCellFormatter().setStyleName(i, k, "empty");
grid.setHTML(i, k, " ");
} else {
HTML html = new CellHTML(
"<span>" + String.valueOf(displayNum) + "</span>",
displayNum);
html.addClickListener(this);
grid.getCellFormatter().setStyleName(i, k, "cell");
if (displayNum == today) {
grid.getCellFormatter().addStyleName(i, k, "today");
} else if (displayNum == sameDay) {
grid.getCellFormatter().addStyleName(i, k, "day");