NullPointer Exception while using docx4j to convert HTML String to Docx

Question

I am using docx4j to convert html strings to docx.

Below is the code.

package docx4j;

import org.docx4j.convert.in.xhtml.FormattingOption;
import org.docx4j.convert.in.xhtml.XHTMLImporter;
import org.docx4j.convert.in.xhtml.XHTMLImporterImpl;
import org.docx4j.openpackaging.exceptions.Docx4JException;
import org.docx4j.openpackaging.io.SaveToZipFile;
import org.docx4j.openpackaging.packages.WordprocessingMLPackage;

public class ConvertHTMLToDoc {

    public static void main(String[] args) throws Docx4JException {

        String outputfilepath = "style-example-OUT30.rtf";

        String text = getHTMLString();

        WordprocessingMLPackage wordMLPackage = WordprocessingMLPackage.createPackage();

        XHTMLImporter xHTMLImporter = new XHTMLImporterImpl(wordMLPackage);

/*      xHTMLImporter.setParagraphFormatting(FormattingOption.CLASS_PLUS_OTHER);
        xHTMLImporter.setRunFormatting(FormattingOption.CLASS_PLUS_OTHER);
*/
        wordMLPackage.getMainDocumentPart().getContent().addAll(xHTMLImporter.convert(text, null));

/*      wordMLPackage.getMainDocumentPart().addStyledParagraphOfText("Title", "Testing Title");
        wordMLPackage.getMainDocumentPart().addStyledParagraphOfText("Subtitle", "Testing Subtitle");
*/
        SaveToZipFile saver = new SaveToZipFile(wordMLPackage);
        saver.save(outputfilepath);
    }

    private static String getHTMLString() {
        String text = "<html><head><title></title></head><body>" + "<p class=\"Title\">Testing Title</p>"
                + "<p class=\"Subtitle\">Testing Subtitle</p>" + "</body></html>";
        return text;
    }

}

When I run this, I get the error at the following line.

wordMLPackage.getMainDocumentPart().getContent().addAll(xHTMLImporter.convert(text, null));

Below is the error message.

12:19:54,125 ERROR [stderr] (http-/0.0.0.0:8080-2) java.lang.NullPointerException

12:19:54,125 ERROR [stderr] (http-/0.0.0.0:8080-2)  at org.docx4j.jaxb.NamespacePrefixMapperUtils.setProperty(NamespacePrefixMapperUtils.java:155)

12:19:54,125 ERROR [stderr] (http-/0.0.0.0:8080-2)  at org.docx4j.XmlUtils.marshaltoString(XmlUtils.java:588)

12:19:54,125 ERROR [stderr] (http-/0.0.0.0:8080-2)  at org.docx4j.XmlUtils.marshaltoString(XmlUtils.java:559)

12:19:54,125 ERROR [stderr] (http-/0.0.0.0:8080-2)  at org.docx4j.openpackaging.parts.WordprocessingML.StyleDefinitionsPart.createVirtualStylesForDocDefaults(StyleDefinitionsPart.java:369)

12:19:54,126 ERROR [stderr] (http-/0.0.0.0:8080-2)  at org.docx4j.openpackaging.parts.WordprocessingML.MainDocumentPart.getStyleTree(MainDocumentPart.java:172)

12:19:54,126 ERROR [stderr] (http-/0.0.0.0:8080-2)  at org.docx4j.openpackaging.parts.WordprocessingML.MainDocumentPart.getStyleTree(MainDocumentPart.java:161)

12:19:54,126 ERROR [stderr] (http-/0.0.0.0:8080-2)  at org.docx4j.convert.in.xhtml.XHTMLImporterImpl.stylesToCSS(XHTMLImporterImpl.java:446)

12:19:54,126 ERROR [stderr] (http-/0.0.0.0:8080-2)  at org.docx4j.convert.in.xhtml.XHTMLImporterImpl.getRenderer(XHTMLImporterImpl.java:253)

12:19:54,126 ERROR [stderr] (http-/0.0.0.0:8080-2)  at org.docx4j.convert.in.xhtml.XHTMLImporterImpl.convert(XHTMLImporterImpl.java:645)

What could be the reason for the null pointer exception?

I have just run your code and it works fine. Do you have also this dependency: `docx4j-ImportXHTML` ? — Paweł Głowacz, Jul 13 '15 at 08:03
When I run this as a standalone then it works fine. When I run this is a part of web application in JBOSS AS 6.2, it doesn't work. — yetanothercoder, Jul 13 '15 at 09:12
I dont have jboss 6.2 installed but checked with tomcat 8. It's working. Are you sure that you have all libs that is required for transformation from html to docx ? How do you build package that contains all required libraries ? Are you using maven and package war for buiilding? — Paweł Głowacz, Jul 13 '15 at 10:15
I bet you are using jdk higher than 6u17 on this JBoss ? Docx4j has problem with NamespacePrefixMapper and propably cant find it and throws NullpointerException. — Paweł Głowacz, Jul 13 '15 at 10:36
Also, this is the main error Caused by: java.lang.ClassNotFoundException: com.sun.xml.internal.bind.marshaller.NamespacePrefixMapper from [Module — yetanothercoder, Jul 13 '15 at 10:43
In jdk with version up to 6u17 there was internal impementation of NamespacePrefixMapper or alteast abstract class of it if i remember correctly. Docx4j used it by default. And this problem occurs on JBoss — Paweł Głowacz, Jul 13 '15 at 10:46

score 1 · Answer 1 · edited May 23 '17 at 11:44

1

There are 2 possibly ways to do this problem:

Less elegant way( You need to create this class in your project. Remember that package com.sun.xml.internal.bind.marshaller name is needed for docx4j. You cannot change that):

package com.sun.xml.internal.bind.marshaller;

public abstract class NamespacePrefixMapper {

private static final String[] EMPTY_STRING = new String[0];

public abstract String getPreferredPrefix(String namespaceUri, String suggestion, boolean requirePrefix);


    public String[] getPreDeclaredNamespaceUris() {
        return EMPTY_STRING;
    }

    public String[] getPreDeclaredNamespaceUris2() {
        return EMPTY_STRING;
    }

public String[] getContextualNamespaceDecls() {
    return EMPTY_STRING;
}
 }

More elegant way but i have no idea if it could work on JBOSS 6.2 since it's for version 7: Docx4j and JBoss 7

edited May 23 '17 at 11:44

Community

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answered Jul 13 '15 at 11:00

Paweł Głowacz

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Check first option for now and see the results. I did this trick sometime ago and it works. – Paweł Głowacz Jul 13 '15 at 11:01
Any conclusion ? Would be great if you could provide any feedback. – Paweł Głowacz Jul 14 '15 at 12:15
1

Just ran into this problem on EAP 6.4 and read this. Can confirm that the "more elegant" solution described for version 7 solved the issue (did not try the first one). – Jaza Nov 11 '19 at 15:24

NullPointer Exception while using docx4j to convert HTML String to Docx

1 Answers1