Removing a row from an Excel sheet with Apache POI HSSF

Question

I'm using the Apache POi HSSF library to import info into my application. The problem is that the files have some extra/empty rows that need to be removed first before parsing.

There's not a HSSFSheet.removeRow( int rowNum ) method. Only removeRow( HSSFRow row ). The problem with this it that empty rows can't be removed. For example:

sheet.removeRow( sheet.getRow(rowNum) );

gives a NullPointerException on empty rows because getRow() returns null. Also, as I read on forums, removeRow() only erases the cell contents but the row is still there as an empty row.

Is there a way of removing rows (empty or not) without creating a whole new sheet without the rows that I want to remove?

Answer 1

I'm trying to reach back into the depths of my brain for my POI-related experience from a year or two ago, but my first question would be: why do the rows need to be removed before parsing? Why don't you just catch the null result from the sheet.getRow(rowNum) call and move on?

Answer 2

The HSSFRow has a method called setRowNum(int rowIndex).

When you have to "delete" a row, you put that index in a List. Then, when you get to the next row non-empty, you take an index from that list and set it calling setRowNum(), and remove the index from that list. (Or you can use a queue)

Answer 3

Something along the lines of

int newrownum=0;
for (int i=0; i<=sheet.sheet.getLastRowNum(); i++) {
  HSSFRow row=sheet.getRow(i);
  if (row) row.setRowNum(newrownum++);
}

should do the trick.

Answer 4

 /**
 * Remove a row by its index
 * @param sheet a Excel sheet
 * @param rowIndex a 0 based index of removing row
 */
public static void removeRow(HSSFSheet sheet, int rowIndex) {
    int lastRowNum=sheet.getLastRowNum();
    if(rowIndex>=0&&rowIndex<lastRowNum){
        sheet.shiftRows(rowIndex+1,lastRowNum, -1);
    }
    if(rowIndex==lastRowNum){
        HSSFRow removingRow=sheet.getRow(rowIndex);
        if(removingRow!=null){
            sheet.removeRow(removingRow);
        }
    }
}