CODEWITHSUNDEEP
javanullpointerexceptiontry-catchitext
Mark
Mark

Reputation: 1400

java itext catching null exception pdf text extraction

When extracting text form pdf using itext 5.3.4 using this code:

try {
    reader = new PdfReader(thepdffilename);
} catch (IOException e) {
    openok=false;
}

if (openok==true){
    int numberOfPages = reader.getNumberOfPages();
    PdfReaderContentParser parser = new PdfReaderContentParser(reader);
    for (int page = 1; page <= numberOfPages; page++){
        try {
              SimpleTextExtractionStrategy strategy = parser.processContent(page, new SimpleTextExtractionStrategy());              
            content = content + strategy.getResultantText();
        } catch (Throwable t) { 
            crap=true;
            break;
        }
    }
    reader.close();
}

However occasionally GooglePlay crashes & ANRs reports that there has been a NP exception in itext.

java.lang.NullPointerException in com.itextpdf.text.pdf.PdfReader$PageRefs.readPages at 
com.itextpdf.text.pdf.PdfReader$PageRefs.readPages(PdfReader.java:3382) at 
com.itextpdf.text.pdf.PdfReader$PageRefs.<init>(PdfReader.java:3350) at com.itextpdf.text.pdf.PdfReader$PageRefs.<init>(PdfReader.java:3328) at 
com.itextpdf.text.pdf.PdfReader.readPages(PdfReader.java:1003) at com.itextpdf.text.pdf.PdfReader.readPdf(PdfReader.java:530) at 
com.itextpdf.text.pdf.PdfReader.<init>(PdfReader.java:170) at 
com.itextpdf.text.pdf.PdfReader.<init>(PdfReader.java:159)

The 5.3.4 source code at line 3382 is:

http://grepcode.com/file/repo1.maven.org/maven2/com.itextpdf/itextpdf/5.3.4/com/itextpdf/text/pdf/PdfReader.java?av=f

3374    void  readPages() throws IOException {
3375      if (refsn != null)
3376           return;
3377        refsp = null;
3378            refsn = new ArrayList<PRIndirectReference>();
3379            pageInh = new ArrayList<PdfDictionary>();
3380            iteratePages((PRIndirectReference)reader.catalog.get(PdfName.PAGES));
3381            pageInh = null;
3382            reader.rootPages.put(PdfName.COUNT, new PdfNumber(refsn.size()));
3383        }
3384
3385    void  reReadPages() throws IOException {
3386            refsn = null;
3387            readPages();
3388    }

So something is going wrong when certain pdf files are having their text extracted and the reason why that could be happening is probably never going to be sorted as I do not have the pdfs in question.

What I require is a method of catching the NP exception so my app does not crash.

I've tried

} catch (Exception e) {

and as a last resort to try and catch any exception

} catch (Throwable t) {

Does anyone have an idea how I can get this particular itext error to be caught?

thanks

Upvotes: 0

Views: 2850

Answers (2)

mkl
mkl

Reputation: 95888

If I understand you correctly, your attempts to catch that NPE have been made in your loop through the document pages:

for (int page = 1; page <= numberOfPages; page++){
    try {
        SimpleTextExtractionStrategy strategy =
            parser.processContent(page, new SimpleTextExtractionStrategy());              
        content = content + strategy.getResultantText();
    } catch (Throwable t) { 
        crap=true;
        break;
    }
}

If you look closely at your Exception, though...

java.lang.NullPointerException in com.itextpdf.text.pdf.PdfReader$PageRefs.readPages at 
com.itextpdf.text.pdf.PdfReader$PageRefs.readPages(PdfReader.java:3382) at 
[...]
com.itextpdf.text.pdf.PdfReader.<init>(PdfReader.java:159)

you see that the exception already occurs in the PdfReader construction (PdfReader.<init>). Thus, you have to catch the NPE already where you construct your PdfReader:

try {
    reader = new PdfReader(thepdffilename);
} catch (IOException e) {
    openok=false;
} catch (NullPointerException npe) { // !!
    openok=false;                    // !!
}

Or if you want to take no chances

try {
    reader = new PdfReader(thepdffilename);
} catch (Throwable t) {              // !!
    openok=false;
}

If you have other code locations, too, in which a PdfReader is constructed, you may want to harden them, too.

@BrunoLowagie This NPE had better be transformed to a tagged exeption, hadn't it?

Upvotes: 3

user18428
user18428

Reputation: 1201

This is ugly but if you really want to catch it , try and catch RuntimeException

Upvotes: 0

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