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javardfjenaturtle-rdf

Jena read from turtle fails

I have just imported jena libraries to eclipse to work on rdf-s and it is my first try, but I cannot read a turtle (.ttl) file.

I tried it in the following way:

import java.io.*;
import java.util.*;
import com.hp.hpl.jena.rdf.model.*;

public class Simpsons {

public static void main(String[] args) throws IOException {
    Model model=ModelFactory.createDefaultModel();
    model.read(new FileInputStream("simpsons.ttl"),null);

}

}

The error I get is the following:

Exception in thread "main" org.apache.jena.riot.RiotException: [line: 1, col: 1 ] Content is not allowed in prolog.
at org.apache.jena.riot.system.ErrorHandlerFactory$ErrorHandlerStd.fatal(ErrorHandlerFactory.java:136)
at org.apache.jena.riot.lang.LangRDFXML$ErrorHandlerBridge.fatalError(LangRDFXML.java:252)
at com.hp.hpl.jena.rdf.arp.impl.ARPSaxErrorHandler.fatalError(ARPSaxErrorHandler.java:48)
at com.hp.hpl.jena.rdf.arp.impl.XMLHandler.warning(XMLHandler.java:209)
at com.hp.hpl.jena.rdf.arp.impl.XMLHandler.fatalError(XMLHandler.java:239)
at org.apache.xerces.util.ErrorHandlerWrapper.fatalError(Unknown Source)
at org.apache.xerces.impl.XMLErrorReporter.reportError(Unknown Source)
at org.apache.xerces.impl.XMLErrorReporter.reportError(Unknown Source)
at org.apache.xerces.impl.XMLErrorReporter.reportError(Unknown Source)
at org.apache.xerces.impl.XMLScanner.reportFatalError(Unknown Source)
at org.apache.xerces.impl.XMLDocumentScannerImpl$PrologDispatcher.dispatch(Unknown Source)
at org.apache.xerces.impl.XMLDocumentFragmentScannerImpl.scanDocument(Unknown Source)
at org.apache.xerces.parsers.DTDConfiguration.parse(Unknown Source)
at org.apache.xerces.parsers.DTDConfiguration.parse(Unknown Source)
at org.apache.xerces.parsers.XMLParser.parse(Unknown Source)
at org.apache.xerces.parsers.AbstractSAXParser.parse(Unknown Source)
at com.hp.hpl.jena.rdf.arp.impl.RDFXMLParser.parse(RDFXMLParser.java:151)
at com.hp.hpl.jena.rdf.arp.ARP.load(ARP.java:119)
at org.apache.jena.riot.lang.LangRDFXML.parse(LangRDFXML.java:142)
at org.apache.jena.riot.RDFParserRegistry$ReaderRIOTFactoryImpl$1.read(RDFParserRegistry.java:142)
at org.apache.jena.riot.RDFDataMgr.process(RDFDataMgr.java:859)
at org.apache.jena.riot.RDFDataMgr.read(RDFDataMgr.java:255)
at org.apache.jena.riot.RDFDataMgr.read(RDFDataMgr.java:241)
at org.apache.jena.riot.adapters.RDFReaderRIOT_Web.read(RDFReaderRIOT_Web.java:62)
at com.hp.hpl.jena.rdf.model.impl.ModelCom.read(ModelCom.java:253)
at assignment2.Simpsons.main(Simpsons.java:11)

Please help me with some ideas because I have no clue what the problem would be as it's my very first try with Jena. I also got a hint from somewhere that I should do the following: :

It seems that Jena is not so good at discovering the RDF serialisation used in files by itself, especially for files addressed with an URL. A solution to this problem is to make a method that gets the file extension of the filename by the use of string functions and returns the appropriate RDF serialisation format in Jena’s predefined strings. You can then use your method both for reading input and writing to file in the correct serialisation format.

but I don't really understand how should I write that method.

Solution

  • The read method you are using assumes that the input format is RDF/XML.

    you need to use one of the other read methods.

    So it would be:

    public static void main(String[] args) throws IOException {
    Model model=ModelFactory.createDefaultModel();
    model.read(new FileInputStream("simpsons.ttl"),null,"TTL");
}