import org.apache.poi.hssf.usermodel.HSSFCell;
import org.apache.poi.hssf.usermodel.HSSFCellStyle;
import org.apache.poi.hssf.usermodel.HSSFDataFormat;
import org.apache.poi.hssf.usermodel.HSSFFont;
import org.apache.poi.hssf.usermodel.HSSFRichTextString;
import org.apache.poi.hssf.usermodel.HSSFRow;
import org.apache.poi.hssf.usermodel.HSSFSheet;
import org.apache.poi.hssf.usermodel.HSSFWorkbook;
import org.apache.poi.ss.util.CellRangeAddress;

public static void main(String[] args) {
HSSFWorkbook wb = HSSFReadWrite.readFile(fileName);

				for (int k = 0; k < wb.getNumberOfSheets(); k++) {
					HSSFSheet sheet = wb.getSheetAt(k);
					int rows = sheet.getPhysicalNumberOfRows();
					//System.out.println("Sheet " + k + " \"" + wb.getSheetName(k) + "\" has " + rows + " row(s).");
					for (int r = 0; r < rows; r++) {
						HSSFRow row = sheet.getRow(r);
						
                                                if (row == null) { continue; }

						int cells = row.getPhysicalNumberOfCells();

как то так......