package jexcel.jxl.nimit;

    import java.awt.Label;  
    import java.io.File;  
    import java.io.IOException;

    import jxl.Cell;   
    import jxl.CellType;  
    import jxl.LabelCell;  
    import jxl.NumberCell;  
    import jxl.Sheet;  
    import jxl.Workbook;  
    import jxl.read.biff.BiffException;  
    import jxl.write.WritableCell;  
    import jxl.write.WritableSheet;  
    import jxl.write.WritableWorkbook;  
    import jxl.write.WriteException;  
    import jxl.write.biff.RowsExceededException;  

    public class ExcelJxl {

    /**
     * @param args
     * @throws IOException 
     * @throws BiffException 
     * @throws WriteException 
     * @throws RowsExceededException 
     */
    public static void main(String[] args) throws BiffException, IOException, RowsExceededException, WriteException {
        // TODO Auto-generated method stub
             ExcelJxl.WriteFile("D:\nimit.xls");
    }

    public static void WriteFile(String path) throws BiffException, IOException, RowsExceededException, WriteException{

    Workbook wb=Workbook.getWorkbook(new File(path));

    WritableWorkbook copy=Workbook.createWorkbook(new File("D:\temp.xls"),wb);
    WritableSheet sheet = copy.getSheet(1); 
    WritableCell cell = sheet.getWritableCell(0,0); 
    String S="nimit";
    if (cell.getType() == CellType.LABEL) 
    { 
      LabelCell l = (LabelCell) cell; 
      l.setString(S); 
    }
    copy.write(); 
    copy.close();
    wb.close();

    }
   }

He editado mi programa, y ​​ahora dice que setString ()El método setString (String) no está definido para el tipo LabelCell Leí la Documentación, hay un método setString en el tipo LabelCell.