How to clone an excel sheet from one workbook to another workbook using Apache POI and Java?

Question

I am trying to copy a formatted excel sheet from one workbook to another which contains merged cells, font size, font color, font face.

I am able to copy all the sheets from multiple excel workbook to a single workbook but I am unable to get the formatting. Please help

import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;

import org.apache.poi.hssf.usermodel.HSSFSheet;
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.CellType;
import org.apache.poi.ss.usermodel.DateUtil;
import org.apache.poi.ss.usermodel.Row;
import org.apache.poi.ss.usermodel.Workbook;

public class CopyExcelSheets {
    public static void main(String args[]) throws IOException {

        //Excel sheet names to read from
        String [] excelSheets = {"Crystal1.xls","Crystal2.xls","Crystal3.xls","Crystal4.xls","Crystal5Complex.xls"};
        //Root folder from where the excel files are read
        final String ROOT_FOLDER = "C:\\demo\\shaji\\";
        //Output file name for merged excel file (consolidated file)
        final String OUTPUT_FILE = "C:\\demo\\shaji\\mergedOutput.xls";

        Workbook [] workbook = new Workbook[excelSheets.length];

        for(int i = 0; i < excelSheets.length; i++) {
            workbook[i] = new HSSFWorkbook(new FileInputStream(ROOT_FOLDER + excelSheets[i]));
        }

        Workbook newWorkbook = new HSSFWorkbook();

        for(int i = 0; i < excelSheets.length; i++) {
            newWorkbook = CopyExcelSheets.copy(workbook[i], newWorkbook, "Book-" + i);
        }       

        //Write over to the new file
        FileOutputStream fileOut;
        fileOut = new FileOutputStream(OUTPUT_FILE);            
        newWorkbook.write(fileOut);

        for(int i = 0; i < excelSheets.length; i++) {
            workbook[i].close();
        }        

        newWorkbook.close();
        fileOut.close();
    }

    /*
     * Based on the implementation by Faraz Durrani on Stackoveflow
     * http://stackoverflow.com/questions/3333021/how-to-copy-one-workbook-sheet-to-another-workbook-sheet-using-apache-poi-and-ja
     */

    public static Workbook copy(Workbook oldWorkbook, Workbook newWorkbook, String bookName) throws IOException {
        // Need this to copy over styles from old sheet to new sheet. Next step will be processed below
        CellStyle newStyle = newWorkbook.createCellStyle(); 
        Row row;
        Cell cell;
        for (int i = 0; i < oldWorkbook.getNumberOfSheets(); i++) {
            HSSFSheet sheetFromOldWorkbook = (HSSFSheet) oldWorkbook.getSheetAt(i);
            HSSFSheet sheetForNewWorkbook = (HSSFSheet) newWorkbook.createSheet(bookName + "-" + sheetFromOldWorkbook.getSheetName());
            for (int rowIndex = 0; rowIndex < sheetFromOldWorkbook.getPhysicalNumberOfRows(); rowIndex++) {
                row = sheetForNewWorkbook.createRow(rowIndex); //create row in this new sheet
                for (int colIndex = 0; colIndex < sheetFromOldWorkbook.getRow(rowIndex).getPhysicalNumberOfCells(); colIndex++) {
                    cell = row.createCell(colIndex); //create cell in this row of this new sheet
                    //get cell from old/original Workbook's sheet and when cell is null, return it as blank cells. 
                    //And Blank cell will be returned as Blank cells. That will not change.
                    Cell c = sheetFromOldWorkbook.getRow(rowIndex).getCell(colIndex, Row.MissingCellPolicy.CREATE_NULL_AS_BLANK ); 
                        if (c.getCellTypeEnum() == CellType.BLANK){
                            //System.out.println("This is BLANK " +  ((XSSFCell) c).getReference());                            
                        }
                        else {  
                        //Below is where all the copying is happening. 
                        //First it copies the styles of each cell and then it copies the content.              
                        CellStyle origStyle = c.getCellStyle();
                        newStyle.cloneStyleFrom(origStyle);
                        cell.setCellStyle(newStyle);            

                         switch (c.getCellTypeEnum()) {
                            case STRING:                            
                                cell.setCellValue(c.getRichStringCellValue().getString());
                                break;
                            case NUMERIC:
                                if (DateUtil.isCellDateFormatted(cell)) {                             
                                    cell.setCellValue(c.getDateCellValue());
                                } else {                              
                                    cell.setCellValue(c.getNumericCellValue());
                                }
                                break;
                            case BOOLEAN:
                                cell.setCellValue(c.getBooleanCellValue());
                                break;
                            case FORMULA:
                                cell.setCellValue(c.getCellFormula());
                                break;
                            case BLANK:
                                cell.setCellValue("");
                                break;
                            default:
                                System.out.println();
                            }
                        }
                    }
                }

            }    

        return newWorkbook;   
    }
}