Tableexport Add-on, Gives null pointer exception !!!

Hi All,

On using this new add-on 'Tableexport' i get null pointer exception. While initializing Export table object.

I am quite new to vaadin, any help would be useful

Below is my code and the exception log

package com.example.tableexport;

import org.apache.poi.hssf.util.HSSFColor;
import org.apache.poi.ss.usermodel.CellStyle;

import com.vaadin.addon.tableexport.ExcelExport;
import com.vaadin.terminal.ThemeResource;
import com.vaadin.ui.Button;
import com.vaadin.ui.Button.ClickEvent;
import com.vaadin.ui.Button.ClickListener;
import com.vaadin.ui.Table;
import com.vaadin.ui.VerticalLayout;

@SuppressWarnings("serial")
public class TableExportExample extends VerticalLayout {
	
	public TableExportExample(){
		
		
		final Table table = new Table("This is my Table");

		/* Define the names and data types of columns.
		 * The "default value" parameter is meaningless here. */
		table.addContainerProperty("First Name", String.class,  null);
		table.addContainerProperty("Last Name",  String.class,  null);
		table.addContainerProperty("Year",       Integer.class, null);

		/* Add a few items in the table. */
		table.addItem(new Object[] {
		    "Nicolaus","Copernicus",new Integer(1473)}, new Integer(1));
		table.addItem(new Object[] {
		    "Tycho",   "Brahe",     new Integer(1546)}, new Integer(2));
		table.addItem(new Object[] {
		    "Giordano","Bruno",     new Integer(1548)}, new Integer(3));
		table.addItem(new Object[] {
		    "Galileo", "Galilei",   new Integer(1564)}, new Integer(4));
		table.addItem(new Object[] {
		    "Johannes","Kepler",    new Integer(1571)}, new Integer(5));
		table.addItem(new Object[] {
		    "Isaac",   "Newton",    new Integer(1643)}, new Integer(6));
		final ThemeResource export = new ThemeResource("../images/table-excel.png");
        final Button excelExportButton = new Button("Export to Excel");
        excelExportButton.setIcon(export);
        
        addComponent(table);
        addComponent(excelExportButton);

        excelExportButton.addListener(new ClickListener() {
            private static final long serialVersionUID = -73954695086117200L;
            private ExcelExport excelExport;

            public void buttonClick(final ClickEvent event) {
            	excelExport = new ExcelExport(table);
                excelExport.excludeCollapsedColumns();
                excelExport.setDisplayTotals(false);
                excelExport.setRowHeaders(true);
                CellStyle cs = excelExport.getTitleStyle();
                cs.setFillBackgroundColor(HSSFColor.GREY_25_PERCENT.index);
                excelExport.setTitleStyle(cs);
                excelExport.setDoubleDataFormat("0.00");
                excelExport.setExcelFormatOfProperty("konto", "0");
                excelExport.export();
            }
        });
	}

}

Exception log

Feb 24, 2012 5:40:03 PM com.vaadin.Application terminalError
SEVERE: Terminal error:
com.vaadin.event.ListenerMethod$MethodException
Cause: java.lang.NullPointerException
	at com.vaadin.event.ListenerMethod.receiveEvent(ListenerMethod.java:532)
	at com.vaadin.event.EventRouter.fireEvent(EventRouter.java:164)
	at com.vaadin.ui.AbstractComponent.fireEvent(AbstractComponent.java:1219)
	at com.vaadin.ui.Button.fireClick(Button.java:550)
	at com.vaadin.ui.Button.changeVariables(Button.java:217)
	at com.vaadin.terminal.gwt.server.AbstractCommunicationManager.changeVariables(AbstractCommunicationManager.java:1451)
	at com.vaadin.terminal.gwt.server.AbstractCommunicationManager.handleVariableBurst(AbstractCommunicationManager.java:1399)
	at com.vaadin.terminal.gwt.server.AbstractCommunicationManager.handleVariables(AbstractCommunicationManager.java:1318)
	at com.vaadin.terminal.gwt.server.AbstractCommunicationManager.doHandleUidlRequest(AbstractCommunicationManager.java:763)
	at com.vaadin.terminal.gwt.server.CommunicationManager.handleUidlRequest(CommunicationManager.java:296)
	at com.vaadin.terminal.gwt.server.AbstractApplicationServlet.service(AbstractApplicationServlet.java:501)
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:722)
	at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:304)
	at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
	at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:240)
	at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:164)
	at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:462)
	at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:164)
	at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:100)
	at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:563)
	at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:118)
	at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:399)
	at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:317)
	at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:204)
	at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:311)
	at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
	at java.lang.Thread.run(Unknown Source)
Caused by: java.lang.NullPointerException
	at org.apache.poi.hssf.model.InternalWorkbook.doesContainsSheetName(InternalWorkbook.java:594)
	at org.apache.poi.hssf.usermodel.HSSFWorkbook.createSheet(HSSFWorkbook.java:740)
	at org.apache.poi.hssf.usermodel.HSSFWorkbook.createSheet(HSSFWorkbook.java:88)
	at com.vaadin.addon.tableexport.ExcelExport.<init>(ExcelExport.java:200)
	at com.vaadin.addon.tableexport.ExcelExport.<init>(ExcelExport.java:177)
	at com.vaadin.addon.tableexport.ExcelExport.<init>(ExcelExport.java:156)
	at com.vaadin.addon.tableexport.ExcelExport.<init>(ExcelExport.java:139)
	at com.vaadin.addon.tableexport.ExcelExport.<init>(ExcelExport.java:125)
	at com.vaadin.addon.tableexport.ExcelExport.<init>(ExcelExport.java:113)
	at com.example.tableexport.TableExportExample$1.buttonClick(TableExportExample.java:52)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
	at java.lang.reflect.Method.invoke(Unknown Source)
	at com.vaadin.event.ListenerMethod.receiveEvent(ListenerMethod.java:512)
	... 27 more

The null pointer exception seems to point to this part of the code 'excelExport = new ExcelExport(table);' .

Any kind of help to solve this problem would be greatly appreciated.

Thanks in advance.
Avinash Nair

Hello.

Did you resolve this problem?

I got the same error.

Thanks for your help.

thanx karan , it workes.