Using Apache POI to write excel file, but FileOutput only contains one column

Question

I've written a code that takes in data from one input excel file and writes a new output file with the desired organization. The problem I'm encountering is that it when I open the Java file only the column that was the latest within the for loop has data. I have tested to see if my for loop is wrong by breaking the for loop at different times. The tests show that it does write the correct data in the correct column. I have no idea why it chooses to erase the previous column. Is there a line I am missing to save the cell values I had just made to keep the data on the sheet I am working on?

import org.apache.poi.hssf.usermodel.HSSFWorkbook;
import org.apache.poi.ss.usermodel.Workbook;
import org.apache.poi.ss.usermodel.Sheet;
import org.apache.poi.ss.usermodel.Row;

import org.apache.poi.ss.usermodel.SheetConditionalFormatting;
import org.apache.poi.ss.usermodel.ConditionalFormattingRule;
import org.apache.poi.ss.util.CellRangeAddress;
import org.apache.poi.ss.usermodel.Cell;
import org.apache.poi.ss.usermodel.ComparisonOperator;//compare two different values
import org.apache.poi.ss.usermodel.PatternFormatting;
import org.apache.poi.ss.usermodel.IndexedColors;


 import java.util.Iterator;
import java.io.*;
import javax.swing.JFileChooser;

public class Reorganizer 
{
public static void main(String[] args)
{
    /*File Chooser*/
    JFileChooser fileChooser = new JFileChooser();//lets user choose file
    int returnValue = fileChooser.showOpenDialog(null);//null bc we don't have parent classes, lets user choose through an open window

    if(returnValue == JFileChooser.APPROVE_OPTION)
    {
        try 
        {
            Workbook wb= new HSSFWorkbook(new FileInputStream(fileChooser.getSelectedFile()));//setting the input file as a workbook
            Sheet inputSheet = wb.getSheetAt(0);//the sheet from the input file

            Workbook wb1 = new HSSFWorkbook();//creating a new workbook to later be put into the output file
            Sheet outputSheet = wb1.createSheet("Sheet 1");//creates new sheet on the output excel file

            //first need something to find cell# of the file
            Row idRow = inputSheet.getRow(0);
            int cellCounter=0;
            for(Iterator<Cell> cit = idRow.cellIterator(); cit.hasNext();)//goes down the row, until there is nothing
            {                   
                Cell cell = cit.next();
                cellCounter++;
            }
            //finds the number of rows
            int rowCounter=0;
            for(Iterator<Row> rit = inputSheet.rowIterator();rit.hasNext();)//goes down the column, until there is nothing
            {                   
                Row row = rit.next();
                rowCounter++;
            }


            //The first row of the document should be the labeling process
            //Set the row(0) and the cells(9)
            Row labelRow = outputSheet.createRow(0);
            //for loop to make 9 cells with labels
            String[] cellValues = new String[]{"Chr","Pos","Olfr","Subfamily","Cluster","OP6u","OP6d","OP27u","OP27d"};
            for(int i=0; i<=9;i++)
            {
                Cell labelCells = labelRow.createCell(i);
                if(i<=8)
                {
                     labelCells.setCellValue(cellValues[i]);
                     for(Iterator<Cell> cit = idRow.cellIterator(); cit.hasNext(); )
                        {
                            Cell cell = cit.next();
                            cell.setCellType(Cell.CELL_TYPE_STRING);
                            if(cellValues[i].equals(cell.getStringCellValue()))
                            {
                                for(int j=1;j<rowCounter;j++)
                                {
                                    int cellnum = cell.getColumnIndex();
                                    Cell inputCell = inputSheet.getRow(j).getCell(cellnum);
                                    inputCell.setCellType(Cell.CELL_TYPE_STRING);
                                    String data = inputCell.getStringCellValue();
                                    Cell outputCell = outputSheet.createRow(j).createCell(i);
                                    outputCell.setCellValue(data);
                                    System.out.println(cellnum);//tells me where the input column was from
                                    System.out.println(i);////tells me what row cell I'm writing on
                                    System.out.println(j);//tells me what row number 
                                    System.out.println(data);//tells me the data being inputed into file
//used the above prints to find out what it was doing, 
//this is the code used to write the data


                                }
                            }

                        }
                } 
                else 
                {
                     labelCells.setCellValue("");
                }

            }

        FileOutputStream output = new FileOutputStream("Reorganized.xls");
        wb1.write(output);
        output.flush();
        output.close();
        }
        catch (FileNotFoundException e) 
        {
            // TODO Auto-generated catch block
            e.printStackTrace();
        } 
        catch (IOException e) 
        {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        catch(Exception e)
        {
            e.printStackTrace();
        }


    }

}

}   

Answer 1

Seem like your problem is here. When you call createRow(), it will erase existing data.

Cell outputCell = outputSheet.createRow(j).createCell(i);

You can either pre-create all the rows before you populate data or you can call getRow() to test if the row already exists. You need something like this:

Row row = outputSheet.getRow(j);
if (row == null) {
    row = outputSheet.createRow(j);
}
Cell outputCell = row.createCell(i);