BC

https://stackoverflow.com/questions/2645566/finding-the-last-row-in-an-excel-spreadsheet

The only way to know for sure is to test the rows. Here's the solution I'm using for the same problem:

int lastRowIndex = -1;
if( sheet.getPhysicalNumberOfRows() > 0 )
{
    // getLastRowNum() actually returns an index, not a row number
    lastRowIndex = sheet.getLastRowNum();

    // now, start at end of spreadsheet and work our way backwards until we find a row having data
    for( ; lastRowIndex >= 0; lastRowIndex-- ){
        Row row = sheet.getRow( lastRowIndex );
        if( row != null ){
            break;
        }
    }
}

Note: this doesn't check for rows that appear to be empty but aren't, such as cells that have an empty string in them. For that, you need a more complete solution like:

private int determineRowCount()
{
    this.evaluator = workbook.getCreationHelper().createFormulaEvaluator();
    this.formatter = new DataFormatter( true );

    int lastRowIndex = -1;
    if( sheet.getPhysicalNumberOfRows() > 0 )
    {
        // getLastRowNum() actually returns an index, not a row number
        lastRowIndex = sheet.getLastRowNum();

        // now, start at end of spreadsheet and work our way backwards until we find a row having data
        for( ; lastRowIndex >= 0; lastRowIndex-- )
        {
            Row row = sheet.getRow( lastRowIndex );
            if( !isRowEmpty( row ) )
            {
                break;
            }
        }
    }
    return lastRowIndex;
}

/**
 * Determine whether a row is effectively completely empty - i.e. all cells either contain an empty string or nothing.
 */
private boolean isRowEmpty( Row row )
{
    if( row == null ){
        return true;
    }

    int cellCount = row.getLastCellNum() + 1;
    for( int i = 0; i < cellCount; i++ ){
        String cellValue = getCellValue( row, i );
        if( cellValue != null && cellValue.length() > 0 ){
            return false;
        }
    }
    return true;
}

/**
 * Get the effective value of a cell, formatted according to the formatting of the cell.
 * If the cell contains a formula, it is evaluated first, then the result is formatted.
 * 
 * @param row the row
 * @param columnIndex the cell's column index
 * @return the cell's value
 */
private String getCellValue( Row row, int columnIndex )
{
    String cellValue;
    Cell cell = row.getCell( columnIndex );
    if( cell == null ){
        // no data in this cell
        cellValue = null;
    }
    else{
        if( cell.getCellType() != Cell.CELL_TYPE_FORMULA ){
            // cell has a value, so format it into a string
            cellValue = this.formatter.formatCellValue( cell );
        }
        else {
            // cell has a formula, so evaluate it
            cellValue = this.formatter.formatCellValue( cell, this.evaluator );
        }
    }
    return cellValue;
}