java - Changing cell color using apache poi

Question

I'm using Apache POI to read data in a spreadsheet of part numbers. I look up the part number in our database, if we have a CAD drawing of the part I color the part number cell green, if we don't I color it red. After the processing is done the spreadsheet is saved. The problem I'm having is that every cell in that column comes out green. I've stepped through the code, the logic to look up the part number is working fine and the logic to determine what color the cell should be and setting the color and fill appears to work as well. Any ideas what I'm doing wrong here?

Thanks.

//Check the parts
for(int r=1;r<sheet.getPhysicalNumberOfRows();r++) {
    String partNumber = null;
    switch(cell.getCellType()) {
        case HSSFCell.CELL_TYPE_NUMERIC:
            long pNum = (long) cell.getNumericCellValue();
            partNumber = String.valueOf(pNum);
            break;
        case HSSFCell.CELL_TYPE_STRING:
            partNumber = cell.getStringCellValue();
            break;
        default:
            logger.info("Part Number at row " + r + " on sheet " + partList.getSheetName(s) + "is of an unsupported type");
    }

    try {
        List<String> oldMaterialNumbers = getOldMaterialNumbers(partNumber);

        boolean gotDrawing = checkPartNumber(oldMaterialNumbers, partNumber);
        //If there's a drawing then color the row green, if not red.
        short bgColorIndex = gotDrawing
                                ?HSSFColor.LIGHT_GREEN.index //42
                                :HSSFColor.RED.index; //10

        HSSFCell curCell = row.getCell(partNumberColumn);
        HSSFCellStyle curStyle = curCell.getCellStyle();

        curStyle.setFillPattern(HSSFCellStyle.SOLID_FOREGROUND);
        curStyle.setFillForegroundColor(bgColorIndex);

        curCell.setCellStyle(curStyle);

    }catch(Exception e) {
        throw e;
    }
}

Answer 1

Short version: Create styles only once, use them everywhere.

Long version: use a method to create the styles you need (beware of the limit on the amount of styles).

private static Map<String, CellStyle> styles;

private static Map<String, CellStyle> createStyles(Workbook wb){
        Map<String, CellStyle> styles = new HashMap<String, CellStyle>();
        DataFormat df = wb.createDataFormat();

        CellStyle style;
        Font headerFont = wb.createFont();
        headerFont.setBoldweight(Font.BOLDWEIGHT_BOLD);
        headerFont.setFontHeightInPoints((short) 12);
        style = createBorderedStyle(wb);
        style.setAlignment(CellStyle.ALIGN_CENTER);
        style.setFont(headerFont);
        styles.put("style1", style);

        style = createBorderedStyle(wb);
        style.setAlignment(CellStyle.ALIGN_CENTER);
        style.setFillForegroundColor(IndexedColors.LIGHT_CORNFLOWER_BLUE.getIndex());
        style.setFillPattern(CellStyle.SOLID_FOREGROUND);
        style.setFont(headerFont);
        style.setDataFormat(df.getFormat("d-mmm"));
        styles.put("date_style", style);
        ...
        return styles;
    }

you can also use methods to do repetitive tasks while creating styles hashmap

private static CellStyle createBorderedStyle(Workbook wb) {
        CellStyle style = wb.createCellStyle();
        style.setBorderRight(CellStyle.BORDER_THIN);
        style.setRightBorderColor(IndexedColors.BLACK.getIndex());
        style.setBorderBottom(CellStyle.BORDER_THIN);
        style.setBottomBorderColor(IndexedColors.BLACK.getIndex());
        style.setBorderLeft(CellStyle.BORDER_THIN);
        style.setLeftBorderColor(IndexedColors.BLACK.getIndex());
        style.setBorderTop(CellStyle.BORDER_THIN);
        style.setTopBorderColor(IndexedColors.BLACK.getIndex());
        return style;
    }

then, in your "main" code, set the style from the styles map you have.

Cell cell = xssfCurrentRow.createCell( intCellPosition );       
cell.setCellValue( blah );
cell.setCellStyle( (CellStyle) styles.get("style1") );