JTable экспорт в excel - Java

Формулировка задачи:

Здравствуйте, подскажите кто знает как экспортировать пустые ячейки JTable в Excel, т.е. у меня есть таблица в которой заполнены не все ячейки, при экспорте такой таблицы появляется ошибка

java.lang.NullPointerException
    at javaapplication120.ExcelExporterProduction.exportTable(ExcelExporterProduction.java:63)
    at javaapplication120.DIpp.jMenuItem1ActionPerformed(DIpp .java:3044)
    at javaapplication120.DIpp.access$3000(DIpp .java:44)
    at javaapplication120.DIpp$39.actionPerformed(DIpp .java:1212)
    at javax.swing.AbstractButton.fireActionPerformed(AbstractButton.java:2022)
    at javax.swing.AbstractButton$Handler.actionPerformed(AbstractButton.java:2348)
    at javax.swing.DefaultButtonModel.fireActionPerformed(DefaultButtonModel.java:402)
    at javax.swing.DefaultButtonModel.setPressed(DefaultButtonModel.java:259)
    at javax.swing.AbstractButton.doClick(AbstractButton.java:376)
    at javax.swing.plaf.basic.BasicMenuItemUI.doClick(BasicMenuItemUI.java:833)
    at javax.swing.plaf.basic.BasicMenuItemUI$Handler.mouseReleased(BasicMenuItemUI.java:877)
    at java.awt.Component.processMouseEvent(Component.java:6533)
    at javax.swing.JComponent.processMouseEvent(JComponent.java:3324)
    at java.awt.Component.processEvent(Component.java:6298)
    at java.awt.Container.processEvent(Container.java:2236)
    at java.awt.Component.dispatchEventImpl(Component.java:4889)
    at java.awt.Container.dispatchEventImpl(Container.java:2294)
    at java.awt.Component.dispatchEvent(Component.java:4711)
    at java.awt.LightweightDispatcher.retargetMouseEvent(Container.java:4888)
    at java.awt.LightweightDispatcher.processMouseEvent(Container.java:4525)
    at java.awt.LightweightDispatcher.dispatchEvent(Container.java:4466)
    at java.awt.Container.dispatchEventImpl(Container.java:2280)
    at java.awt.Window.dispatchEventImpl(Window.java:2746)
    at java.awt.Component.dispatchEvent(Component.java:4711)
    at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:758)
    at java.awt.EventQueue.access$500(EventQueue.java:97)
    at java.awt.EventQueue$3.run(EventQueue.java:709)
    at java.awt.EventQueue$3.run(EventQueue.java:703)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:76)
    at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:86)
    at java.awt.EventQueue$4.run(EventQueue.java:731)
    at java.awt.EventQueue$4.run(EventQueue.java:729)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:76)
    at java.awt.EventQueue.dispatchEvent(EventQueue.java:728)
    at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:201)
    at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:116)
    at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:105)
    at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:101)
    at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:93)
    at java.awt.EventDispatchThread.run(EventDispatchThread.java:82)

соответственно ругается на то что не вся таблица заполнена. А добавлять в каждую ячейку нули и потом их удалять в excel не очень то и охота. вот сам код экспорта

/*
 * To change this template, choose Tools | Templates
 * and open the template in the editor.
 */
package javaapplication120;
 
import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import javax.swing.JTable;
import javax.swing.table.TableModel;
import org.apache.poi.hssf.usermodel.HSSFWorkbook;
import org.apache.poi.ss.util.CellRangeAddress;
import org.apache.poi.ss.usermodel.Cell;
import org.apache.poi.ss.usermodel.CellStyle;
import org.apache.poi.ss.usermodel.Row;
import org.apache.poi.ss.usermodel.Sheet;
import org.apache.poi.ss.usermodel.Workbook;
import org.apache.poi.ss.util.RegionUtil;
 
/**
 *
 * @author admin
 */
class ExcelExporterProduction {
 
    ExcelExporterProduction() {
    }
 
    public void exportTable(JTable jTable1, File file) throws IOException {
        FileOutputStream out = null;
        Workbook wb = new HSSFWorkbook();
        Sheet sheet = wb.createSheet("new sheet");
        int colCount = jTable1.getColumnCount();
        int colRow = jTable1.getRowCount();
        Row row = null;
        Cell cell = null;
        TableModel model = jTable1.getModel();
        out = new FileOutputStream(file);
        String a[] = {"Наименование", "ед.изм"};
        //экспорт заголовка таблицы
        sheet.shiftRows(0, jTable1.getColumnCount(), 1);
        sheet.addMergedRegion(new CellRangeAddress(0, 1, 0, 0));
        sheet.addMergedRegion(new CellRangeAddress(0, 1, 1, 1));
 
        for (int j = 0; j <= jTable1.getRowCount(); j++) {
            row = sheet.createRow(j);
            for (int i = 0; i < model.getColumnCount(); i++) {
                cell = row.createCell(i);
                cell.setCellValue(model.getColumnName(i).toString());
            }
        }
        sheet.addMergedRegion(new CellRangeAddress(0, 0, 2, 3));
        sheet.addMergedRegion(new CellRangeAddress(0, 0, 4, 5));
        sheet.addMergedRegion(new CellRangeAddress(0, 0, 6, 7));
        sheet.addMergedRegion(new CellRangeAddress(0, 0, 8, 9));
        //экспорт данных из таблицы в ексель     
        for (int i = 0; i < jTable1.getRowCount(); i++) {
            row = sheet.createRow(i + 2);
            int f = jTable1.getColumnCount();
            for (int j = 0; j < jTable1.getColumnCount(); j++) {
                cell = row.createCell(j);
                cell.setCellValue(jTable1.getValueAt(i, j).toString());
 
            }
        }
        for (int k = 0; k < 1; k++) {
            row = sheet.createRow(k);
            for (int j = 0; j < 12; j++) {
                if (j < 2) {
                    cell = row.createCell(j);
                    cell.setCellValue(a[j].toString());
                } else {
                    cell = row.createCell(j);
                    switch (j) {
                        case 2:
                            cell.setCellValue("Остаток");
                            break;
                        case 4:
                            cell.setCellValue("Приход(ДТ)");
                            break;
                        case 6:
                            cell.setCellValue("Расход(КТ)");
                            break;
                        case 8:
                            cell.setCellValue("Остаток");
                            break;
                        default:
                            break;
                    }
                }
            }
        }
        //прорисовка границ в ексель
        for (int y = 0; y <= colRow + 1; y++) {
            for (int x = 0; x < colCount; x++) {
                CellRangeAddress range = new CellRangeAddress(y, y, x, x);
                RegionUtil.setBorderTop(CellStyle.BORDER_THIN, range, sheet, wb);
                RegionUtil.setBorderRight(CellStyle.BORDER_THIN, range, sheet, wb);
                RegionUtil.setBorderBottom(CellStyle.BORDER_THIN, range, sheet, wb);
                RegionUtil.setBorderLeft(CellStyle.BORDER_THIN, range, sheet, wb);
            }
        }
        for (int i = 0; i < colCount - 1; i++) {
            setBorder(colRow, colCount);
            sheet.autoSizeColumn(i);
        }
        sheet.setColumnWidth(0, 4000);
        sheet.setVerticallyCenter(Boolean.TRUE);
        wb.write(out);
        out.close();
    }
 
    private void setBorder(int i, int j) {
        Workbook wb = new HSSFWorkbook();
        Sheet sheet = wb.createSheet("new sheet");
        for (int y = 0; y <= i; y++) {
            for (int x = 0; x < j; x++) {
                CellRangeAddress range = new CellRangeAddress(y, y, x, x);
                RegionUtil.setBorderTop(CellStyle.BORDER_THIN, range, sheet,
                        wb);
                RegionUtil.setBorderRight(CellStyle.BORDER_THIN, range, sheet,
                        wb);
                RegionUtil.setBorderBottom(CellStyle.BORDER_THIN, range, sheet,
                        wb);
                RegionUtil.setBorderLeft(CellStyle.BORDER_THIN, range, sheet,
                        wb);
            }
        }
    }
}

и метод который вызывает этот класс

  try {
            JFileChooser fileChooser = new JFileChooser();
            int retval = fileChooser.showSaveDialog(jButton1);
            if (retval == JFileChooser.APPROVE_OPTION) {
                File file = fileChooser.getSelectedFile();
                if (file != null) {
                    if (!file.getName().toLowerCase().endsWith(".xls")) {
                        file = new File(file.getParentFile(), file.getName() + ".xls");
                    }
                    try {
                        ExcelExporterProduction exp = new ExcelExporterProduction();
                        exp.exportTable(jTable2, file);
                    } catch (UnsupportedEncodingException e) {
                        e.printStackTrace();
 
                    } catch (FileNotFoundException e) {
                        e.printStackTrace();
                        System.out.println("not found");
                    } catch (IOException e) {
                        e.printStackTrace();
                    }
                }
            }
        } catch (Exception e) {
            e.printStackTrace();
        }

Решение задачи: «JTable экспорт в excel»

textual
                            Листинг программы 
                        
                               cell.setCellValue(jTable1.getValueAt(i, j).toString());