Question

Okay. I have a main UI with buttons on it. When a user clicks one of the buttons it should bring up a listview created by a separate activity. When I run this activity by itself, as it’s own app, it’s works just fine, but when I try to use it as component of a larger app, it shuts the app down. Here’s the code for the activity I’m trying to call:

table.java

public class Table extends Activity {
/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.main_table);
    ListView lv= (ListView)findViewById(R.id.listview);

    ArrayList<HashMap<String, String>> mylist = new ArrayList<HashMap<String, String>>();


    String xml = XMLfunctions.getXML();
    Document doc = XMLfunctions.XMLfromString(xml);

    int numResults = XMLfunctions.numResults(doc);

    if((numResults <= 0)){
        Toast.makeText(Table.this, "Nothing to show.", Toast.LENGTH_LONG).show();  
        finish();
    }

    NodeList nodes = doc.getElementsByTagName("team");

    for (int i = 0; i < nodes.getLength(); i++) {                           
        HashMap<String, String> map = new HashMap<String, String>();    

        Element e = (Element)nodes.item(i);
        map.put("rowid", XMLfunctions.getValue(e, "id"));           
        map.put("name", XMLfunctions.getValue(e, "name"));
        map.put("w",  XMLfunctions.getValue(e, "w"));
        map.put("d",  XMLfunctions.getValue(e, "d"));
        map.put("l",  XMLfunctions.getValue(e, "l"));
        map.put("gd",  XMLfunctions.getValue(e, "gd"));
        map.put("pts", XMLfunctions.getValue(e, "pts"));
        mylist.add(map);            
    }       


    //Make a new listadapter
    ListAdapter adapter = new SimpleAdapter(this, mylist , R.layout.grid_item,
                    new String[] { "rowid", "name", "w" , "d", "l", "gd", "pts"},
                    new int[] {R.id.item1, R.id.item2, R.id.item3, R.id.item4, R.id.item5, R.id.item6, R.id.item7 });

       lv.setAdapter(adapter);


}

The table.java activity parses the xml data that this class pulls:

XMLfunctions.java

public class XMLfunctions {

public final static Document XMLfromString(String xml){

    Document doc = null;

    DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();
    try {

        DocumentBuilder db = dbf.newDocumentBuilder();

        InputSource is = new InputSource();
        is.setCharacterStream(new StringReader(xml));
        doc = db.parse(is); 

    } catch (ParserConfigurationException e) {
        System.out.println("XML parse error: " + e.getMessage());
        return null;
    } catch (SAXException e) {
        System.out.println("Wrong XML file structure: " + e.getMessage());
        return null;
    } catch (IOException e) {
        System.out.println("I/O exeption: " + e.getMessage());
        return null;
    }

    return doc;

}

/** Returns element value
  * @param elem element (it is XML tag)
  * @return Element value otherwise empty String
  */
 public final static String getElementValue( Node elem ) {
     Node kid;
     if( elem != null){
         if (elem.hasChildNodes()){
             for( kid = elem.getFirstChild(); kid != null; kid = kid.getNextSibling() ){
                 if( kid.getNodeType() == Node.TEXT_NODE  ){
                     return kid.getNodeValue();
                 }
             }
         }
     }
     return "";
 }

 public static String getXML(){  
        String line = null;

        try {

            DefaultHttpClient httpClient = new DefaultHttpClient();
            HttpPost httpPost = new HttpPost("http://adasoccerclub.org/get_json.php");

            HttpResponse httpResponse = httpClient.execute(httpPost);
            HttpEntity httpEntity = httpResponse.getEntity();
            line = EntityUtils.toString(httpEntity);

        } catch (UnsupportedEncodingException e) {
            line = "<results status=\"error\"><msg>Can't connect to server</msg></results>";
        } catch (MalformedURLException e) {
            line = "<results status=\"error\"><msg>Can't connect to server</msg></results>";
        } catch (IOException e) {
            line = "<results status=\"error\"><msg>Can't connect to server</msg></results>";
        }

        return line;

}

public static int numResults(Document doc){     
    Node results = doc.getDocumentElement();
    int res = -1;

    try{
        res = Integer.valueOf(results.getAttributes().getNamedItem("count").getNodeValue());
    }catch(Exception e ){
        res = -1;
    }

    return res;
}

public static String getValue(Element item, String str) {       
    NodeList n = item.getElementsByTagName(str);        
    return XMLfunctions.getElementValue(n.item(0));
}

Finally, here’s the LogCat from the debug:

03-05 23:43:54.858: E/AndroidRuntime(9190): FATAL EXCEPTION: main

03-05 23:43:54.858: E/AndroidRuntime(9190): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.club/com.example.club.Table}: android.os.NetworkOnMainThreadException

03-05 23:43:54.858: E/AndroidRuntime(9190): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1955)

03-05 23:43:54.858: E/AndroidRuntime(9190): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1980)

03-05 23:43:54.858: E/AndroidRuntime(9190): at android.app.ActivityThread.access$600(ActivityThread.java:122)

03-05 23:43:54.858: E/AndroidRuntime(9190): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1146)

03-05 23:43:54.858: E/AndroidRuntime(9190): at android.os.Handler.dispatchMessage(Handler.java:99)

03-05 23:43:54.858: E/AndroidRuntime(9190): at android.os.Looper.loop(Looper.java:137)

03-05 23:43:54.858: E/AndroidRuntime(9190): at android.app.ActivityThread.main(ActivityThread.java:4340)

03-05 23:43:54.858: E/AndroidRuntime(9190): at java.lang.reflect.Method.invokeNative(Native Method)

03-05 23:43:54.858: E/AndroidRuntime(9190): at java.lang.reflect.Method.invoke(Method.java:511)

03-05 23:43:54.858: E/AndroidRuntime(9190): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:784)

03-05 23:43:54.858: E/AndroidRuntime(9190): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:551)

03-05 23:43:54.858: E/AndroidRuntime(9190): at dalvik.system.NativeStart.main(Native Method)

03-05 23:43:54.858: E/AndroidRuntime(9190): Caused by: android.os.NetworkOnMainThreadException

03-05 23:43:54.858: E/AndroidRuntime(9190): at android.os.StrictMode$AndroidBlockGuardPolicy.onNetwork(StrictMode.java:1084)

03-05 23:43:54.858: E/AndroidRuntime(9190): at java.net.InetAddress.lookupHostByName(InetAddress.java:391)

03-05 23:43:54.858: E/AndroidRuntime(9190): at java.net.InetAddress.getAllByNameImpl(InetAddress.java:242)

03-05 23:43:54.858: E/AndroidRuntime(9190): at java.net.InetAddress.getAllByName(InetAddress.java:220)

03-05 23:43:54.858: E/AndroidRuntime(9190): at org.apache.http.impl.conn.DefaultClientConnectionOperator.openConnection(DefaultClientConnectionOperator.java:137)

03-05 23:43:54.858: E/AndroidRuntime(9190): at org.apache.http.impl.conn.AbstractPoolEntry.open(AbstractPoolEntry.java:164)

03-05 23:43:54.858: E/AndroidRuntime(9190): at org.apache.http.impl.conn.AbstractPooledConnAdapter.open(AbstractPooledConnAdapter.java:119)

03-05 23:43:54.858: E/AndroidRuntime(9190): at org.apache.http.impl.client.DefaultRequestDirector.execute(DefaultRequestDirector.java:360)

03-05 23:43:54.858: E/AndroidRuntime(9190): at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:555)

03-05 23:43:54.858: E/AndroidRuntime(9190): at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:487)

03-05 23:43:54.858: E/AndroidRuntime(9190): at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:465)

03-05 23:43:54.858: E/AndroidRuntime(9190): at com.example.club.ClubActivity$XMLfunctions.getXML(ClubActivity.java:205)

03-05 23:43:54.858: E/AndroidRuntime(9190): at com.example.club.MainTable.onCreate(Table.java:30)

03-05 23:43:54.858: E/AndroidRuntime(9190): at android.app.Activity.performCreate(Activity.java:4465)

03-05 23:43:54.858: E/AndroidRuntime(9190): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1049)

03-05 23:43:54.858: E/AndroidRuntime(9190): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1919)

Thanks for any and all help!

Answer 1

If you see your logcat, that itself says NetworkOnMainThreadException at com.example.club.ClubActivity$XMLfunctions.getXML(ClubActivity.java:205). In getXML, you are doing network operation which is heavy operation in nature. You only can think of it like if you getXML which you are calling in onCreate of Activity is taking so much time to load/fetch data from server, it will halt the Activity to come to full visible state and you may definitely get famous ANR (Application Not Responding) dialog. So to avoid this, android doc suggests to do heavy operations (like network operations) in background thread so that UI renders within specified time.

So its better you change your logic and fetch network data using AsyncTask or a new thread with the help of Handler.