Java - Using Jena APi - Get data from RDF file

Question

My question concerns the class Person with the datatype properties hasFirstName , hasLastName , hasDateOfBirth , hasGender . I'm using Java and Jena API.

Here is how one person is represented in my RDF file.

<rdf:Description rdf:about="http://www.fam.com/FAM#Bruno04/02/1980 ">
    <j.0:FAMhasGender>H</j.0:FAMhasGender>
    <j.0:FAMhasDateOfBirth>04/02/1980</j.0:FAMhasDateOfBirth>
    <j.0:FAMhasLastName>DS </j.0:FAMhasLastName>
    <j.0:FAMhasFirstName> Bruno</j.0:FAMhasFirstName>
 </rdf:Description>

I want to write this line below if gender is female :

[label= \"" +firstName+ " \"\n\n\"D.Naiss:"+dnai1+"\", "+shape2+"]

so if there is, for example, 3 females the file must contain 3 lines with that format. The shape value( and then the output line) will depend on the gender, that's why i cannot not use the same line for both genders. Shape2 if female and shape if male.

For each person whose gender is male I want to output this line below:

[label= \"" +firstName+ " \"\n\n\"D.Naiss:"+dnai1+"\", "+**shape**+"]

The problem I have is that he outputs only one woman and one man with the corresponding line. However, I have more than one woman and man in my rdf file.

Here is the relevant code. Can you tell me what should I modify to solve this? Thank you very much.

public void accessProp() {

    readFile(inputFile); // rdf
    String fname;
    String dd;
    String gen;

    ExtendedIterator instances = onto.person.listInstances();
    Individual instance = null;
    Individual firstInstance = null;
    while (instances.hasNext()) {
        instance = (Individual) instances.next();

        gen = instance.getPropertyValue(onto.hasGender).toString();
        fname = instance.getPropertyValue(onto.hasFirstName).toString();
        dd = instance.getPropertyValue(onto.hasDateOfBirth).toString();

        writeFile(fname, dd, genr);
    }
}

// Write text file
public void writeFile(String fn, String dbir, String gn) {
    String fileout = "D:/file1.txt";
    String firstName = fn;
    String dateB = dbir;
    String gender = gn;

    BufferedWriter out;
    try {
        out = new BufferedWriter(new FileWriter(fileout, true));

        if (gender.equals("F")) {
            out.write("[label= \"" + firstName + " \"\n\n\"D.Naiss:" + dnai1 + "\", " + shape + "]");
        } else if (gender.equals("M")) {
            out.write("[label= \"" + firstName + " \"\n\n\"D.Naiss:" + dnai1 + "\", " + shape2 + "]");
        }

        out.newLine();

        // flushes and closes the stream
        out.close();
    } catch (IOException e) {
        System.out.println("There was a problem:" + e);
    }
}

Answer 1

Without knowing Jena, I do not see any place in your code where you only select the male entries. Check that while (instances.hasNext()) { loop to see what instances it loops through.

Because you write for each of that instances a line, the writeLine() method writes both, male and female entries, it might be that

ExtendedIterator instances = onto.person.listInstances();

returns the two male and female entries you see in your file.

Also, your example RDF entry has a value of H for gender, but in your code you are using M and F to check it.