Stuck with XmlPullParser in Android

Question

After multiple hours of searching and debugging I'm still stuck at the same place and Eclipse is not helping me.

I trying to parsing this rss feed

which is pretty simple. The Connection is done and I transform the InputStream as a String this works well.

When I try to parse the String obtained, I have no errors or warnings but the values i try to have are null. Here is the XML process

public class XmlOperations {
private static final String ns = null;

public List parse(String in) throws XmlPullParserException, IOException {
    try {

        XmlPullParser parser = Xml.newPullParser();
        parser.setFeature(XmlPullParser.FEATURE_PROCESS_NAMESPACES, false);
        parser.setInput(new StringReader(in));
        parser.nextTag();
        return readFeed(parser);
    } finally {
        // 
    }
}

private List readFeed(XmlPullParser parser) throws XmlPullParserException, IOException {
    List entries = new ArrayList();
    // first xml balise
    parser.require(XmlPullParser.START_TAG, ns,"rss"); 
    while (parser.next() != XmlPullParser.END_TAG) {
        if (parser.getEventType() != XmlPullParser.START_TAG) {
            continue;
        }
        String name = parser.getName();
        Log.w(TAG, name); // output channel the first time
        // Starts by looking for the item tag
        if (name.equals("item")) {
            **Log.w(TAG, "Never get in here" )**
          entries.add(readEntry(parser));
        } else {
            skip(parser);
            Log.w(TAG, "lala");
        }
    }  
    return entries;
}



// Parses the contents of an item. If it encounters a title, description, or link tag, hands them off
// to their respective "read" methods for processing. Otherwise, skips the tag.
private Entry readEntry(XmlPullParser parser) throws XmlPullParserException, IOException {
    parser.require(XmlPullParser.START_TAG, ns, "item");
    String title = null;
    String description = null;
    String link = null;
    while (parser.next() != XmlPullParser.END_TAG) {
        if (parser.getEventType() != XmlPullParser.START_TAG) {
            continue;
        }
        String name = parser.getName();
        if (name.equals("title")) {
            title = readTitle(parser);
        } else if (name.equals("description")) {
            description = readDescription(parser);
        } else if (name.equals("link")) {
            link = readLink(parser);
        } else {
            skip(parser);
        }
    }
    return new Entry(title, description, link);
}

// Processes title tags in the feed.
private String readTitle(XmlPullParser parser) throws IOException, XmlPullParserException {
    parser.require(XmlPullParser.START_TAG, ns, "title");
    String title = readText(parser);
    parser.require(XmlPullParser.END_TAG, ns, "title");
    return title;
}

// Processes link tags in the feed.
private String readLink(XmlPullParser parser) throws IOException, XmlPullParserException {
    parser.require(XmlPullParser.START_TAG, ns, "link");
    String link = readText(parser);
    parser.require(XmlPullParser.END_TAG, ns, "link");
    return link;
}

// Processes summary tags in the feed.
private String readDescription(XmlPullParser parser) throws IOException, XmlPullParserException {
    parser.require(XmlPullParser.START_TAG, ns, "description");
    String description = readText(parser);
    parser.require(XmlPullParser.END_TAG, ns, "description");
    //Log.d("vALUE = ", summary);
    return description;
}

// For the tags title and description, extracts their text values.
private String readText(XmlPullParser parser) throws IOException, XmlPullParserException {
    String result = "";
    if (parser.next() == XmlPullParser.TEXT) {
        result = parser.getText();
        parser.nextTag();
    }
    return result;
}

private void skip(XmlPullParser parser) throws XmlPullParserException, IOException {
    if (parser.getEventType() != XmlPullParser.START_TAG) {
        throw new IllegalStateException();
    }
    int depth = 1;
    while (depth != 0) {
        switch (parser.next()) {
        case XmlPullParser.END_TAG:
            depth--;
            break;
        case XmlPullParser.START_TAG:
            depth++;
            break;
        }
    }
 }

I suppose error is in one of the parsing methods.

In antoher class I have this

XmlOperations xml = new XmlOperations();
        try {
            entrieses = xml.parse(result);
            String lol = null;
            for(Entry item : entrieses) {
                //Toast.makeText(getApplicationContext(), item.title, Toast.LENGTH_SHORT).show();
                lol = item.link.toString();
            }
            tv.setText("Pin " + lol + " gouin");

entreses is a List of Entry. And still equals null :(

EDIT: With the log cat I have channel lala and that's all

Can you show a sample of the output? Might also be a good idea to quote some of the current rss feed data, in case it goes away or changes. — itsbruce
– itsbruce, Commented Nov 16, 2012 at 15:32
There are no outputs in LogCat in error or warning. The output of the Textview is Pin null gouin — Freego
– Freego, Commented Nov 16, 2012 at 15:36
can u try set a breakpoint to check if your entries.add does add the parsed items? Or you can simply add some logcat out put to log what the parser is doing. — dumbfingers
– dumbfingers, Commented Nov 16, 2012 at 15:55
Ok guys, I think you headed me right. When I log in the readFeed method my first item is <channel> so go in the skip(parser) method but then when i should iterate to the next xml item it doesn't. I 'll modify my code so you can see. — Freego
– Freego, Commented Nov 16, 2012 at 16:48

Freego · Accepted Answer · 2012-11-16 18:34:10Z

1

I finally find out. My code was right, my XML comprehension wasn't. The XML goes like this

<rss>
    <channel>
        <item>
            <link> </link>
            <title> </title>
        </item>
    </channel>
</rss>

My code went to channel and then next channel, but it doesn't exist. I just had to add parser.Next() in my reedFeed() function just before the loop to pass the channel tag and go directly to the item tag. And it works :)

answered Nov 16, 2012 at 18:34

Freego

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Comments

Drake Clarris · Accepted Answer · 2012-11-16 18:22:50Z

0

I think the line in your readFeed() function needs to be while (parser.next() != XmlPullParser.END_DOCUMENT) { instead of while (parser.next() != XmlPullParser.END_TAG) {, because otherwise it is returning nearly right away.

answered Nov 16, 2012 at 18:22

Drake Clarris

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