尝试解析Excel文件

Question

I'm trying to parse excel file in such a way that when I find an empty cell I add to the value of string. Sample code:

for (int e = 0; e < wb.getNumberOfSheets(); e++) {
    sheet = wb.getSheetAt(e);
    for (int i = sheet.getFirstRowNum(); i < sheet.getLastRowNum(); i++) {
        System.out.println(sheet.getSheetName());
        row = sheet.getRow(i);
        if(row != null) {
            cell = row.getCell(0, Row.RETURN_BLANK_AS_NULL);
            if(cell.getCellType() != Cell.CELL_TYPE_BLANK) {
                cell = row.createCell(i);
                cell.setCellValue("foo");
            }
            cell = row.getCell(1, Row.RETURN_BLANK_AS_NULL);
            if(cell == null) {
                cell = row.createCell(i);
                cell.setCellValue("bar");
            }
            cell = row.getCell(2, Row.RETURN_BLANK_AS_NULL);
            if(cell == null) {
                cell = row.createCell(i);
                cell.setCellValue(0.0);
            }
        }
}

I tried many solutions, and I always get an exception NullPointerException.

Answer 1

Could be useful to know which line gives you the exception, but I bet it's this one:

cell = row.getCell(0, Row.RETURN_BLANK_AS_NULL);
if(cell.getCellType() != Cell.CELL_TYPE_BLANK) {

As far as I know, the policy RETURN_BLANK_AS_NULL returns a null value if the cell is empty. So, if you get a blank cell there, the cell.getCellType() in the if statement raises a NullPointerException.

Answer 2

You have NPE in first check, the cell is null:

cell = row.getCell(0, Row.RETURN_BLANK_AS_NULL);
if(cell.getCellType() != Cell.CELL_TYPE_BLANK) {

later you check correctly:

cell = row.getCell(2, Row.RETURN_BLANK_AS_NULL);
if(cell == null) {

to create new cell use

Row.CREATE_NULL_AS_BLANK