Merge and align center cell using apache poi

Question

I want to export data to excel using Apache poi.
Now the problem that I am facing is that I am unable to merge rows and align them in the center.

Code for export data is:

List<LinkedHashMap<String,Object>> lstReportHeader = null;
HSSFWorkbook wb = new HSSFWorkbook();
HSSFSheet sheet = wb.createSheet();

//Set Header Font
HSSFFont headerFont = wb.createFont();
headerFont.setBoldweight(headerFont.BOLDWEIGHT_BOLD);
headerFont.setFontHeightInPoints((short) 12);

//Set Header Style
CellStyle headerStyle = wb.createCellStyle();
headerStyle.setFillBackgroundColor(IndexedColors.BLACK.getIndex());
headerStyle.setAlignment(headerStyle.ALIGN_CENTER);
headerStyle.setFont(headerFont);
headerStyle.setBorderBottom(HSSFCellStyle.BORDER_MEDIUM);
int rowCount= 0;
Row header;
header = sheet.createRow(0);//its for header 
Cell cell ;//= header.createCell(0);
for(int j = 0;j < 4; j++) {
    cell = header.createCell(j);
    if(j == 0) {
        cell.setCellValue("ItemWise List");
    }
    cell.setCellStyle(headerStyle);
}
sheet.addMergedRegion(new CellRangeAddress(rowCount, rowCount, 0, lstReportFormHeader.size()-1));
header = sheet.createRow(0);
        cell = header.createCell(0);
cell.setCellValue("Sr. No");
        cell = header.createCell(1);
cell.setCellValue("Item Name");
        cell = header.createCell(2);
cell.setCellValue("Qty");
        cell = header.createCell(3);
cell.setCellValue("Rate");

Now I want to ItemWise List merge and make it align center.

Answer 1

My solution was to merge the cells by their positions, then created a cell (reference to the first block of the merged cells) to assign a value and then set the alignment throught the CellUtil

// Merges the cells
CellRangeAddress cellRangeAddress = new CellRangeAddress(start, start, j, j + 1);
sheet.addMergedRegion(cellRangeAddress);

// Creates the cell
Cell cell = CellUtil.createCell(row, j, entry.getKey());

// Sets the allignment to the created cell
CellUtil.setAlignment(cell, workbook, CellStyle.ALIGN_CENTER);

Answer 2

Merge like:::

 Workbook wb = new HSSFWorkbook();
Sheet sheet = wb.createSheet("new sheet");

Row row = sheet.createRow((short) 1);
Cell cell = row.createCell((short) 1);
cell.setCellValue("This is a test of merging");

sheet.addMergedRegion(new CellRangeAddress(
        1, //first row (0-based)
        1, //last row  (0-based)
        1, //first column (0-based)
        2  //last column  (0-based)
));

// Write the output to a file
FileOutputStream fileOut = new FileOutputStream("workbook.xls");
wb.write(fileOut);
fileOut.close();

For aligning also check the below official link of Apache poi:::

http://poi.apache.org/spreadsheet/quick-guide.html#Alignment

Answer 3

After study I found that after merging 7 cells, merged cell id will be 0 so I applied following style to cell id 0 using following style.

headerStyle.setAlignment(headerStyle.ALIGN_CENTER);

Answer 4

As per my understanding, you have start and end cells for merging and you want to merge the cell ranges and align the cell content. If I am right, you can use the following method:

/**
 * @param startCell: first cell of merging area
 * @param endCell: last cell of merging area
 */

public static void mergeAndAlignCenter(HSSFCell startCell, HSSFCell endCell){
    //finding reference of start and end cell; will result like $A$1
    CellReference startCellRef= new CellReference(startCell.getRowIndex(),startCell.getColumnIndex());
    CellReference endCellRef = new CellReference(endCell.getRowIndex(),endCell.getColumnIndex());
    // forming string of references; will result like $A$1:$B$5 
    String cellRefernce = startCellRef.formatAsString()+":"+endCellRef.formatAsString();
    //removing $ to make cellRefernce like A1:B5
    cellRefernce = cellRefernce.replace("$","");
    //passing cellRefernce to make a region 
    CellRangeAddress region = CellRangeAddress.valueOf(cellRefernce);
    //use region to merge; though other method like sheet.addMergedRegion(new CellRangeAddress(1,1,4,1));
    // is also available, but facing some problem right now.
    startCell.getRow().getSheet().addMergedRegion( region );
    //setting alignment to center
    CellUtil.setAlignment(startCell, wb, CellStyle.ALIGN_CENTER);
}

Answer 5

Well what worked for me is to set all the merged cells' Cellstyle to CENTER ALIGN. Whether you put the XSSFSheet.addMergedRegion() method before or after setting the cellstyle values to center don't matter.

    private void insertXlsHeader(XSSFSheet sheet){
    ....
    //first cell for row1       
    cell = row1.createCell(colstart);
    cell.setCellType(org.apache.poi.ss.usermodel.Cell.CELL_TYPE_STRING);
    cell.setCellValue("COURSES");
    setHeaderCellStyle(sheet,cell);

    //first cell for row2
    cell = row2.createCell(colstart);
    setHeaderCellStyle(sheet,cell);

    //first cell for row3
    cell = row3.createCell(colstart);
    setHeaderCellStyle(sheet,cell);

    //merged the first cells of rows 1 to 3
    sheet.addMergedRegion(new CellRangeAddress(ROW1, ROW3, colstart, colstart));
    ...
    }

private void setHeaderCellStyle(XSSFSheet sheet,org.apache.poi.ss.usermodel.Cell cell) {
    CellStyle s = null;

        s = sheet.getWorkbook().createCellStyle();
        cell.setCellStyle(s);

    Font f = sheet.getWorkbook().createFont();

    f.setBoldweight(Font.BOLDWEIGHT_BOLD);


    s.setBorderBottom(CellStyle.BORDER_THIN);
    s.setBorderLeft(CellStyle.BORDER_THIN);
    s.setBorderRight(CellStyle.BORDER_THIN);
    s.setBorderTop(CellStyle.BORDER_THIN);
    s.setVerticalAlignment(CellStyle.VERTICAL_CENTER);
    s.setAlignment(CellStyle.ALIGN_CENTER);
    s.setFont(f);

}

Answer 6

This worked for me and I think it's cleaner:

/**
 * Merge and center the cells specified by range
 * @param startCell the first cell in the cells to be merged
 * @param range the range of the cells to be merged
 */
private static void mergeAndCenter(Cell startCell, CellRangeAddress range) {
    startCell.getSheet().addMergedRegion(range);
    CellStyle style = startCell.getSheet().getWorkbook().createCellStyle();
    style.setAlignment(CellStyle.ALIGN_CENTER);
    style.setVerticalAlignment(CellStyle.VERTICAL_CENTER);
    startCell.setCellStyle(style);
}

Answer 7

As answered above, merging cells can be achieved using

sheet.addMergedRegion(new CellRangeAddress(frstRow, lastRow, firstColumnIndex, lastColumnIndex));

But for aligning cells vertically,recently I faced similar issue and I tried above answer, but using

CellUtil.setAlignment(dataCell, workbook, CellStyle.VERTICAL_CENTER);

aligned Date formatted cells to Horizontal Left aligned. So I used following method to set only Vertical Alignment of Cell content.

CellUtil.setCellStyleProperty(dataCell, workbook,CellUtil.VERTICAL_ALIGNMENT,CellStyle.VERTICAL_CENTER);

I hope this helps!!

Happy Coding

Answer 8

Use

style.setVerticalAlignment()

to set the vertical alignments instead of

style.setAlignment().