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I 'm building a JSP web application using Eclipse IDE. The web application loads without issue on tomcat server ver 7. We got a new requirement to read from xls and xlsx file. So we have used Apache POI library (4.1.2) to implement this as follows: I have taken out other codes as they are not relevant for this post

FileInputStream file = new FileInputStream(new File(args[0]));

        //Create Workbook instance holding reference to .xlsx file
        XSSFWorkbook workbook = new XSSFWorkbook(file); //<- This is where the exception occurs

        //Get first/desired sheet from the workbook
        XSSFSheet sheet = workbook.getSheetAt(0);

        //Iterate through each rows one by one
        Iterator<Row> rowIterator = sheet.iterator();

But when executing we are getting the below exception. I have tried googling but didn't find relevant help. Can you please assist?

SEVERE: Servlet.service() for servlet [UploadEstimates] in context with path [/AD] threw exception [Servlet execution threw an exception] with root cause
java.lang.NullPointerException
at org.apache.xmlbeans.impl.schema.ClassLoaderResourceLoader.getResourceAsStream(ClassLoaderResourceLoader.java:33)
at org.apache.xmlbeans.impl.schema.SchemaTypeSystemImpl$XsbReader.getLoaderStream(SchemaTypeSystemImpl.java:2249)
at org.apache.xmlbeans.impl.schema.SchemaTypeSystemImpl$XsbReader.<init>(SchemaTypeSystemImpl.java:1522)
at org.apache.xmlbeans.impl.schema.SchemaTypeSystemImpl.initFromHeader(SchemaTypeSystemImpl.java:273)
at org.apache.xmlbeans.impl.schema.SchemaTypeSystemImpl.<init>(SchemaTypeSystemImpl.java:185)
at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
at sun.reflect.NativeConstructorAccessorImpl.newInstance(Unknown Source)
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(Unknown Source)
at java.lang.reflect.Constructor.newInstance(Unknown Source)
at schemaorg_apache_xmlbeans.system.sD023D6490046BA0250A839A9AD24C443.TypeSystemHolder.loadTypeSystem(Unknown Source)
at schemaorg_apache_xmlbeans.system.sD023D6490046BA0250A839A9AD24C443.TypeSystemHolder.<clinit>(Unknown Source)
at sun.misc.Unsafe.ensureClassInitialized(Native Method)
at sun.reflect.UnsafeFieldAccessorFactory.newFieldAccessor(Unknown Source)
at sun.reflect.ReflectionFactory.newFieldAccessor(Unknown Source)
at java.lang.reflect.Field.acquireFieldAccessor(Unknown Source)
at java.lang.reflect.Field.getFieldAccessor(Unknown Source)
at java.lang.reflect.Field.get(Unknown Source)
at org.apache.xmlbeans.XmlBeans.typeSystemForClassLoader(XmlBeans.java:775)
at org.openxmlformats.schemas.drawingml.x2006.main.ThemeDocument.<clinit>(Unknown Source)
at org.openxmlformats.schemas.drawingml.x2006.main.ThemeDocument$Factory.parse(Unknown Source)
at org.apache.poi.xssf.model.ThemesTable.<init>(ThemesTable.java:86)
at org.apache.poi.ooxml.POIXMLFactory.createDocumentPart(POIXMLFactory.java:61)
at org.apache.poi.ooxml.POIXMLDocumentPart.read(POIXMLDocumentPart.java:684)
at org.apache.poi.ooxml.POIXMLDocument.load(POIXMLDocument.java:180)
at org.apache.poi.xssf.usermodel.XSSFWorkbook.<init>(XSSFWorkbook.java:288)
at org.apache.poi.xssf.usermodel.XSSFWorkbook.<init>(XSSFWorkbook.java:342)
at com.MyClient.AD.util.UploadEstimateUT.start(UploadEstimateUT.java:85)
at com.MyClient.AD.util.UploadEstimates.doPost(UploadEstimates.java:107)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:754)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:847)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:303)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208)
at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:241)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:219)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:110)
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:492)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:165)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:104)
at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:1025)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:116)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:452)
at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1195)
at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:654)
at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:319)
at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
at java.lang.Thread.run(Unknown Source)

This is how I referenced the POI files: MyProject -> Right Click -> Build Path -> Configure Built Path -> Libraries tab and added the following jars

enter image description here

And this is how I execute the application Run -> Run Configuration... -> Classpath tab -> Making sure all jar files are referenced here including Apache POI's -> Apply and/or Run.

enter image description here

Update 1 (28-Feb-2020)

I tried the same code (that reads from excel using POI library) as java application and it worked as expected.

Another thing I noted when debugging the JSP web application is that the control is transferred directly to the finally block instead of the general Exception block. Not sure why.

Update 2 (03-Mar-2020)

I configured the project in my colleagues system who also has Eclipse IDE but with Tomcat server version 9.0.31 and it worked in his machine.

Then I installed Tomcat server version 9.0.31 and configured the project from a separate workspace but when executing I face the same exception. I'm not able to understand what could the difference.

We both are using Eclipse IDE for Enterprise Java Developers. Version: 2019-09 R (4.13.0) Build id: 20190917-1200

Update 3 (06-Mar-2020)

magicmn, I get the below exception after updating to factory method

    SEVERE: Servlet.service() for servlet [UploadEstimates] in context with path [/AD] threw exception [Servlet execution threw an exception] with root cause
java.lang.NullPointerException
    at org.apache.xmlbeans.impl.schema.ClassLoaderResourceLoader.getResourceAsStream(ClassLoaderResourceLoader.java:33)
    at org.apache.xmlbeans.impl.schema.SchemaTypeSystemImpl$XsbReader.getLoaderStream(SchemaTypeSystemImpl.java:2249)
    at org.apache.xmlbeans.impl.schema.SchemaTypeSystemImpl$XsbReader.<init>(SchemaTypeSystemImpl.java:1522)
    at org.apache.xmlbeans.impl.schema.SchemaTypeSystemImpl.initFromHeader(SchemaTypeSystemImpl.java:273)
    at org.apache.xmlbeans.impl.schema.SchemaTypeSystemImpl.<init>(SchemaTypeSystemImpl.java:185)
    at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
    at sun.reflect.NativeConstructorAccessorImpl.newInstance(Unknown Source)
    at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(Unknown Source)
    at java.lang.reflect.Constructor.newInstance(Unknown Source)
    at schemaorg_apache_xmlbeans.system.sD023D6490046BA0250A839A9AD24C443.TypeSystemHolder.loadTypeSystem(Unknown Source)
    at schemaorg_apache_xmlbeans.system.sD023D6490046BA0250A839A9AD24C443.TypeSystemHolder.<clinit>(Unknown Source)
    at sun.misc.Unsafe.ensureClassInitialized(Native Method)
    at sun.reflect.UnsafeFieldAccessorFactory.newFieldAccessor(Unknown Source)
    at sun.reflect.ReflectionFactory.newFieldAccessor(Unknown Source)
    at java.lang.reflect.Field.acquireFieldAccessor(Unknown Source)
    at java.lang.reflect.Field.getFieldAccessor(Unknown Source)
    at java.lang.reflect.Field.get(Unknown Source)
    at org.apache.xmlbeans.XmlBeans.typeSystemForClassLoader(XmlBeans.java:775)
    at org.openxmlformats.schemas.drawingml.x2006.main.ThemeDocument.<clinit>(Unknown Source)
    at org.openxmlformats.schemas.drawingml.x2006.main.ThemeDocument$Factory.parse(Unknown Source)
    at org.apache.poi.xssf.model.ThemesTable.<init>(ThemesTable.java:86)
    at org.apache.poi.ooxml.POIXMLFactory.createDocumentPart(POIXMLFactory.java:61)
    at org.apache.poi.ooxml.POIXMLDocumentPart.read(POIXMLDocumentPart.java:684)
    at org.apache.poi.ooxml.POIXMLDocument.load(POIXMLDocument.java:180)
    at org.apache.poi.xssf.usermodel.XSSFWorkbook.<init>(XSSFWorkbook.java:288)
    at org.apache.poi.xssf.usermodel.XSSFWorkbookFactory.createWorkbook(XSSFWorkbookFactory.java:97)
    at org.apache.poi.xssf.usermodel.XSSFWorkbookFactory.createWorkbook(XSSFWorkbookFactory.java:125)
    at org.apache.poi.ss.usermodel.WorkbookFactory.create(WorkbookFactory.java:327)
    at org.apache.poi.ss.usermodel.WorkbookFactory.create(WorkbookFactory.java:295)
    at org.apache.poi.ss.usermodel.WorkbookFactory.create(WorkbookFactory.java:276)
    at com.MyClient.AD.util.UploadEstimateUT.start(UploadEstimateUT.java:90)
    at com.MyClient.AD.util.UploadEstimates.doPost(UploadEstimates.java:108)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:660)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:741)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:231)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
    at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:53)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:202)
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:96)
    at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:541)
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:139)
    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:92)
    at org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:688)
    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:74)
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:343)
    at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:367)
    at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:65)
    at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:868)
    at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1639)
    at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
    at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
    at java.lang.Thread.run(Unknown Source)
Improve this question
14
  • 1
    Have you confirmed that the FileStream is not null? Commented Feb 27, 2020 at 15:29
  • Please share contents of args[] array Commented Feb 27, 2020 at 20:36
  • Yes @ChadNC, the filestream is not null. Commented Feb 28, 2020 at 4:10
  • @shihabudheenk, args[0] holds the path of the file like C:\\Program Files\\Apache Software Foundation\\Tomcat 7.0\\wtpwebapps\\MyWebProject\\excel\\myexcel.xlsx Commented Feb 28, 2020 at 4:13
  • Friends, I have some update (Update 1 added in the main thread) on this issue. Please see if that can help you Commented Feb 28, 2020 at 12:54

4 Answers 4

Reset to default
1
+50

The NullPointerException is thrown at line 33 of ClassLoaderResourceLoader. The line is:

return _classLoader.getResourceAsStream(resourceName);

Which means that _classLoader is null. _classLoader is passed to the constructor.

The ClassLoaderResourceLoader object is created at line 182 of SchemaTypeSystemImpl:

_classloader = indexclass.getClassLoader();
...
_resourceLoader = new ClassLoaderResourceLoader(_classloader);

Which means that _classloader is null, which means that indexclass.getClassLoader() is null.

When can getClassLoader() return null? The documentation says:

Some implementations may use null to represent the bootstrap class loader. This method will return null in such implementations if this class was loaded by the bootstrap class loader.

Bootstrap? Does it ring a bell? Yes, you put all your jars in the Bootstrap Entries, which means that they are loaded by the bootstrap class loader. As I said in a comment (which you seem to have ignored), the correct location for jars is the WEB-INF\lib directory of the application. So just put them in there and it will work.

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Comments

0

I tried posting a comment but my rank does not allow me to do so. This is not an answer(so please don't be harsh) but it is what I would've done in your case(I have been working with java and excel files for the last month and I am quite good).

File myFile=new File(args[0]);
if(myFile==null)System.out.println("my file is null");else System.out.println("my file is NOT null");
FileInputStream file = new FileInputStream(new File(args[0]));

You can post your results and I will take a stab at it.

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3 Comments

thank you looking into my issue. I added the null check code and debugged the application. The control came to non-null area and the console window displayed "my file is NOT null". Just like i mentioned in my original post that the same code works in my colleague's machine but not mine. Not sure what is the difference.
Hi Hemant. Got it. I have been reading up on javarevisited.blogspot.com/2014/07/… and have a suggestion. Try removing the absolute path to your file and use a relative one and see if that works.
Hi Sherma234, no matter whatever virtual path I try, I always get java.io.FileNotFoundException: \excel\123.xlsx. But I think locating file is not the issue. Because even when I hardcode to an existing file, the exception stays as posted in my original request.
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Are you sure upload is finished before you try to read file? because from stacktrace: at com.MyClient.AD.util.UploadEstimateUT.start(UploadEstimateUT.java:85) it's on start of upload

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1 Comment

Hi wikprim, Yes, i checked and see the file present in the location by two methods: 1. I degugged the code and stopped at the point where Workbook is ready to be initialized referring the file from the location. I opened and see that the file is opening and the records are present in it. I closed and continued debugging and still the NullPointerException. 2. I hard coded the file location where the xlsx file is already present and yet again the exception happens.
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I know I had a similar problem with POI when I received a Resource from a Spring rest service, before saving and then reopening it.

Have you tried the following things?

  • Write the file somewhere else. Then read it.

  • Use an xls Workbook. Generally I recommend to use Workbook workbook = WorkbookFactory.create(input); to create your Workbook. One of the great strengths of POI is that it offers the Workbook interface to have standardized operations for XLS and XLSX files.

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2 Comments

Hi magicmn, I have updated my code and I still get the same NullPointerException.
Hi magicmn, I have added the exception details in the main post under update 3. Please see if this helps in further narrowing of the problem. I have also tried by hardcoding reading the xlsx from a different path

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