Parsing XML with XmlPullParserFactory is crashing in while statement

https://stackoverflow.com/questions/18602900

27-06-2022
|

Question

I am using a XmlPullParserFactory object to parse some XML that I receive from my server. For some reason it crashes at the while statement and I can't figure out why that would happen.

XML:

<?xml version="1.0" encoding="UTF-8"?>
<body>
<item>
  <id>115240</id>
  <title>
    <![CDATA[Student Evangelism Team Leaves for Fiji]]>
  </title>
  <created>20130821-15:50</created>
  <author>
    <![CDATA[Staff Writer]]>
  </author>
  <summary>
    <![CDATA[On August 21, Service, Justice, and Missions Coordinator Fabio Maia and ten
      Pacific Union College students left for an eighteen-day evangelism mission in
      Fiji with ShareHim and Quiet Hour Ministries.]]>
  </summary>
  <body_text>
    <![CDATA[<p>On August 21, Service, Justice, and Missions Coordinator
      Fabio Maia and ten Pacific Union College students left for an eighteen-day
      evangelism mission in Fiji with ShareHim and Quiet Hour Ministries. Each
      student will be placed in a specific community where they will present the
      story of Christ’s love and sacrifice each evening. Many of the students are
      active in the college’s praise and worship teams and brought their instruments
      so they can share God’s love through music.</p>
      <p>Before the group departed, the students gathered in
      President Heather J. Knight’s office for a special blessing prayer led by
      Pastor Mark Witas, the lead pastor of the PUC Church. Pastor Witas included
      special prayer that God lead the group in doing good in His name. <a></a>The group also
      bonded by sharing a meal together before heading to the airport for their
      flight to Fiji.</p>
      <p>For many PUC students, summer is the perfect opportunity to
      devote time to ministry and service. While some students work at summer camps
      or serve as literature evangelists, other groups get the experience of a
      lifetime by sharing the gospel and serving local communities in places around
      the world. The PUC community is invited to join in prayer for the team travelling
      to Fiji as well as other student groups currently on short-term mission trips
      to Nicaragua and Brazil.</p>]]>
  </body_text>
  <url>http://www.puc.edu/news/archives/2013/student-evangelism-team-leaves-for-fiji</url>
  <images>
    <image url="http://www.puc.edu/__data/assets/image/0014/115241/fiji.jpg" url_2x="http://www.puc.edu/__data/assets/image/0014/115241/varieties/2x.jpg" thumb_small="http://www.puc.edu/__data/assets/image/0014/115241/varieties/thumb.jpg" thumb_medium="http://www.puc.edu/__data/assets/image/0014/115241/varieties/thumb_large.jpg" thumb_large="http://www.puc.edu/__data/assets/image/0014/115241/varieties/thumb_large.jpg" />
  </images>
  </item>
... lots more item nodes
</body>

Java:

class PUCNewsItem
{

    public String title;
    public String summary;
    public String body;
    public String url;
    public String imageUrl;

}

public class PUCDatasource extends Activity {

    public static ArrayList<PUCNewsItem> getPUCNews() throws IOException {

            String url = "http://api.mysite.com/list";
            InputStream is = downloadUrl(url);
            XmlPullParserFactory pullParserFactory;

            try {
                pullParserFactory = XmlPullParserFactory.newInstance();
                XmlPullParser parser = pullParserFactory.newPullParser();
                parser.setInput(is, null);

                ArrayList<PUCNewsItem> items = null;
                int eventType = parser.getEventType();
                PUCNewsItem item = null;
                Log.d("Debug: ", "Start");
                while (eventType != XmlPullParser.END_DOCUMENT){
                    String name = null;
                    switch (eventType){
                        case XmlPullParser.START_DOCUMENT:
                            Log.d("Debug: ", "Start doc");
                            items = new ArrayList<PUCNewsItem>();
                            break;
                        case XmlPullParser.START_TAG:
                            name = parser.getName();
                            if (name == "item"){
                                item = new PUCNewsItem();
                            } else if (item != null){
                                if (name == "title"){
                                    item.title = parser.nextText();
                                } else if (name == "summary"){
                                    item.summary = parser.nextText();
                                } else if (name == "body_text"){
                                    item.body = parser.nextText();
                                }  
                            }
                            break;
                        case XmlPullParser.END_TAG:
                            name = parser.getName();
                            if (name.equalsIgnoreCase("item") && item != null) {
                                items.add(item);
                            }
                            break;
                    }//end switch

                    eventType = parser.next();

                }//end while

                return items;

            } catch (XmlPullParserException e) {
                e.printStackTrace();
            } catch (IOException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }

            return null;

        }//end

}//end class

Errors:

09-03 16:31:50.100: W/System.err(16727): Invalid stream or encoding: java.io.IOException: Stream is closed (position:START_DOCUMENT null@1:1) caused by: java.io.IOException: Stream is closed; nested exception is:
09-03 16:31:50.108: W/System.err(16727): java.io.IOException: Stream is closed
09-03 16:31:50.108: W/System.err(16727):    at java.util.zip.GZIPInputStream.read(GZIPInputStream.java:158)
09-03 16:31:50.108: W/System.err(16727):    at libcore.io.Streams.readSingleByte(Streams.java:41)
09-03 16:31:50.108: W/System.err(16727):    at java.util.zip.InflaterInputStream.read(InflaterInputStream.java:128)
09-03 16:31:50.108: W/System.err(16727):    at org.kxml2.io.KXmlParser.setInput(KXmlParser.java:1623)
09-03 16:31:50.108: W/System.err(16727):    at com.puc.mobile.PUCDatasource.getPUCNews(PUCDatasource.java:40)
09-03 16:31:50.108: W/System.err(16727):    at com.puc.mobile.MainActivity$DownloadPUCNews.doInBackground(MainActivity.java:94)
09-03 16:31:50.108: W/System.err(16727):    at com.puc.mobile.MainActivity$DownloadPUCNews.doInBackground(MainActivity.java:1)
09-03 16:31:50.108: W/System.err(16727):    at android.os.AsyncTask$2.call(AsyncTask.java:264)
09-03 16:31:50.108: W/System.err(16727):    at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:305)
09-03 16:31:50.108: W/System.err(16727):    at java.util.concurrent.FutureTask.run(FutureTask.java:137)
09-03 16:31:50.108: W/System.err(16727):    at android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:208)
09-03 16:31:50.108: W/System.err(16727):    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1076)
09-03 16:31:50.108: W/System.err(16727):    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:569)
09-03 16:31:50.108: W/System.err(16727):    at java.lang.Thread.run(Thread.java:856)
09-03 16:31:50.108: D/AndroidRuntime(16727): Shutting down VM
09-03 16:31:50.108: W/dalvikvm(16727): threadid=1: thread exiting with uncaught exception (group=0x40aba210)
09-03 16:31:50.108: E/AndroidRuntime(16727): FATAL EXCEPTION: main
09-03 16:31:50.108: E/AndroidRuntime(16727): java.lang.NullPointerException
09-03 16:31:50.108: E/AndroidRuntime(16727):    at com.puc.mobile.MainActivity$DownloadPUCNews.onPostExecute(MainActivity.java:103)
09-03 16:31:50.108: E/AndroidRuntime(16727):    at com.puc.mobile.MainActivity$DownloadPUCNews.onPostExecute(MainActivity.java:1)
09-03 16:31:50.108: E/AndroidRuntime(16727):    at android.os.AsyncTask.finish(AsyncTask.java:602)
09-03 16:31:50.108: E/AndroidRuntime(16727):    at android.os.AsyncTask.access$600(AsyncTask.java:156)
09-03 16:31:50.108: E/AndroidRuntime(16727):    at android.os.AsyncTask$InternalHandler.handleMessage(AsyncTask.java:615)
09-03 16:31:50.108: E/AndroidRuntime(16727):    at android.os.Handler.dispatchMessage(Handler.java:99)
09-03 16:31:50.108: E/AndroidRuntime(16727):    at android.os.Looper.loop(Looper.java:137)
09-03 16:31:50.108: E/AndroidRuntime(16727):    at android.app.ActivityThread.main(ActivityThread.java:4697)
09-03 16:31:50.108: E/AndroidRuntime(16727):    at java.lang.reflect.Method.invokeNative(Native Method)
09-03 16:31:50.108: E/AndroidRuntime(16727):    at java.lang.reflect.Method.invoke(Method.java:511)
09-03 16:31:50.108: E/AndroidRuntime(16727):    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:787)
09-03 16:31:50.108: E/AndroidRuntime(16727):    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:554)
09-03 16:31:50.108: E/AndroidRuntime(16727):    at dalvik.system.NativeStart.main(Native Method)

Any ideas on why the crash is happening? Should I somehow be specifying the name of my roote node?

Solution

The problem doesn't appear to be the while loop, according to the stack trace.

09-03 16:31:50.108: W/System.err(16727): java.io.IOException: Stream is closed
09-03 16:31:50.108: W/System.err(16727):    at java.util.zip.GZIPInputStream.read(GZIPInputStream.java:158)
09-03 16:31:50.108: W/System.err(16727):    at libcore.io.Streams.readSingleByte(Streams.java:41)
09-03 16:31:50.108: W/System.err(16727):    at java.util.zip.InflaterInputStream.read(InflaterInputStream.java:128)
09-03 16:31:50.108: W/System.err(16727):    at org.kxml2.io.KXmlParser.setInput(KXmlParser.java:1623)

It's throwing an exception at the setInput() in your code, before the while loop.

The root cause here could be a lot of things. I'd start by looking at the downloadUrl() code, and see if there's any reason why it might be returning a stream that's already closed.

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