Apache-POI sorting rows in excel

Question

I'd like to sort rows in a sheet by one of string column. I tried to achive that using Sheet.shiftRows method, but I cannot manage with that. It doesn't switch positions of rows in my method. What's wrong in my code? Or maybe there is better way to sort rows by any String column in excel?

/**
 * Sorts (A-Z) rows by String column
 * @param sheet - sheet to sort
 * @param column - String column to sort by
 * @param rowStart - sorting from this row down
 */
private void sortSheet(Sheet sheet, int column, int rowStart) {
    boolean sorting = true;
    int lastRow = sheet.getLastRowNum();
    while (sorting == true) {
        sorting = false;
        for (Row row : sheet) {
            // skip if this row is before first to sort
            if (row.getRowNum()<rowStart) continue;
            // end if this is last row
            if (lastRow==row.getRowNum()) break;
            Row row2 = sheet.getRow(row.getRowNum()+1);
            if (row2 == null) continue;
            String firstValue = (row.getCell(column) != null) ? row.getCell(column).getStringCellValue() : "";
            String secondValue = (row2.getCell(column) != null) ? row2.getCell(column).getStringCellValue() : "";
            //compare cell from current row and next row - and switch if secondValue should be before first
            if (secondValue.compareToIgnoreCase(firstValue)<0) {                    
                sheet.shiftRows(row2.getRowNum(), row2.getRowNum(), -1);
                sheet.shiftRows(row.getRowNum(), row.getRowNum(), 1);
                sorting = true;
            }
        }
    }
}

Any idea how to manage row sorting in a sheet?

UPDATE The method above works since Apache-POI 3.9 version.

EDIT: Added missing bracket -helvio

Answer 1

Poi has no built in sorting mechanism, though of course you are far from the first one with that need.

I think you are getting in trouble because you are moving rows that you are iterating over. I have run the code above and it seems what is happening is rows are disappearing from the sheet by the end of the code execution.

The question attempts to do an in-place modification of a read-in sheet. I believe that creating a second output sheet would be more appropriate.

So the basic approach would be read the sheet, sort in java just as you would treat any other sort problem, write to output sheet. If you did a map of the row number which is unique to the string value of the column you are interested in then you could sort the map by value. This sort of approach would work if you only foresaw the need to sort on a single column. In any event, it is not as simple as just choosing the sort menu option from within excel.

Answer 2

Now I now why it's not working. There is a bug in shiftRows method. When third argument (number of rows to shift) is negative, it causes troubles.

This is described here: https://issues.apache.org/bugzilla/show_bug.cgi?id=53798

UPDATE This bug has been fixed from version 3.9

Answer 3

To sort rows you need to:

• copy all rows to temp
• sort rows in the temp
• remove all rows from sheet
• create new rows with values of sorted rows from temp

Code:

import org.apache.commons.compress.utils.Lists;
import org.apache.poi.hssf.usermodel.HSSFOptimiser;
import org.apache.poi.hssf.usermodel.HSSFWorkbook;
import org.apache.poi.ss.usermodel.Cell;
import org.apache.poi.ss.usermodel.CellStyle;
import org.apache.poi.ss.usermodel.Row;
import org.apache.poi.ss.usermodel.Sheet;
import org.apache.poi.ss.usermodel.Workbook;
import org.apache.poi.ss.util.CellRangeAddress;

import java.util.List;

public static void sortSheet(Workbook workbook, Sheet sheet) {
        //copy all rows to temp
        List<Row> rows = Lists.newArrayList(sheet.rowIterator());
        //sort rows in the temp
        rows.sort(Comparator.comparing(cells -> cells.getCell(0).getStringCellValue()));
        //remove all rows from sheet
        removeAllRows(sheet);
        //create new rows with values of sorted rows from temp
        for (int i = 0; i < rows.size(); i++) {
            Row newRow = sheet.createRow(i);
            Row sourceRow = rows.get(i);
            // Loop through source columns to add to new row
            for (int j = 0; j < sourceRow.getLastCellNum(); j++) {
                // Grab a copy of the old/new cell
                Cell oldCell = sourceRow.getCell(j);
                Cell newCell = newRow.createCell(j);

                // If the old cell is null jump to next cell
                if (oldCell == null) {
                    newCell = null;
                    continue;
                }

                // Copy style from old cell and apply to new cell
                CellStyle newCellStyle = workbook.createCellStyle();
                newCellStyle.cloneStyleFrom(oldCell.getCellStyle());
                newCell.setCellStyle(newCellStyle);

                // If there is a cell comment, copy
                if (oldCell.getCellComment() != null) {
                    newCell.setCellComment(oldCell.getCellComment());
                }

                // If there is a cell hyperlink, copy
                if (oldCell.getHyperlink() != null) {
                    newCell.setHyperlink(oldCell.getHyperlink());
                }

                // Set the cell data type
                newCell.setCellType(oldCell.getCellType());

                // Set the cell data value
                switch (oldCell.getCellType()) {
                    case BLANK:
                        newCell.setCellValue(oldCell.getStringCellValue());
                        break;
                    case BOOLEAN:
                        newCell.setCellValue(oldCell.getBooleanCellValue());
                        break;
                    case ERROR:
                        newCell.setCellErrorValue(oldCell.getErrorCellValue());
                        break;
                    case FORMULA:
                        newCell.setCellFormula(oldCell.getCellFormula());
                        break;
                    case NUMERIC:
                        newCell.setCellValue(oldCell.getNumericCellValue());
                        break;
                    case STRING:
                        newCell.setCellValue(oldCell.getRichStringCellValue());
                        break;
                }
            }

            // If there are are any merged regions in the source row, copy to new row
            for (int j = 0; j < sheet.getNumMergedRegions(); j++) {
                CellRangeAddress cellRangeAddress = sheet.getMergedRegion(j);
                if (cellRangeAddress.getFirstRow() == sourceRow.getRowNum()) {
                    CellRangeAddress newCellRangeAddress = new CellRangeAddress(newRow.getRowNum(),
                            (newRow.getRowNum() +
                                    (cellRangeAddress.getLastRow() - cellRangeAddress.getFirstRow()
                                    )),
                            cellRangeAddress.getFirstColumn(),
                            cellRangeAddress.getLastColumn());
                    sheet.addMergedRegion(newCellRangeAddress);
                }
            }
        }

    }

    private static void removeAllRows(Sheet sheet) {
            for (int i = 0; i < sheet.getLastRowNum(); i++) {
                sheet.removeRow(sheet.getRow(i));
            }
        }

Answer 4

Write a program to read the xlsx file and perform the below listed operations:-

Item, Quantity and Price is mandatory fields. Call out if any records doesn't have these. Sort the records based on “Group code” . Separate out the date from the “Header Description” and add another column as “Delivery Date”. Save the processed data in the new xlsx file.