android trouble with starting activity

Question

I have quite a bit of a problem on my hands. My application keeps crashing and this what my stacktrace keeps saying

07-26 10:48:30.582: E/AndroidRuntime(2334): FATAL EXCEPTION: main
07-26 10:48:30.582: E/AndroidRuntime(2334): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.theproblemsolver/com.theproblemsolver.ListView}: android.os.NetworkOnMainThreadException
07-26 10:48:30.582: E/AndroidRuntime(2334):     at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2230)
07-26 10:48:30.582: E/AndroidRuntime(2334):     at android.app.ActivityThread.access$600(ActivityThread.java:141)
07-26 10:48:30.582: E/AndroidRuntime(2334):     at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1234)
07-26 10:48:30.582: E/AndroidRuntime(2334):     at android.os.Handler.dispatchMessage(Handler.java:99)
07-26 10:48:30.582: E/AndroidRuntime(2334):     at android.os.Looper.loop(Looper.java:137)
07-26 10:48:30.582: E/AndroidRuntime(2334):     at android.app.ActivityThread.main(ActivityThread.java:5041)
07-26 10:48:30.582: E/AndroidRuntime(2334):     at java.lang.reflect.Method.invokeNative(Native Method)
07-26 10:48:30.582: E/AndroidRuntime(2334):     at java.lang.reflect.Method.invoke(Method.java:511)
07-26 10:48:30.582: E/AndroidRuntime(2334):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:793)
07-26 10:48:30.582: E/AndroidRuntime(2334):     at java.net.InetAddress.lookupHostByName(InetAddress.java:385)
07-26 10:48:30.582: E/AndroidRuntime(2334):     at java.net.InetAddress.getAllByNameImpl(InetAddress.java:236)
07-26 10:48:30.582: E/AndroidRuntime(2334):     at java.net.InetAddress.getAllByName(InetAddress.java:214)
07-26 10:48:30.582: E/AndroidRuntime(2334):     at org.apache.http.impl.conn.DefaultClientConnectionOperator.openConnection(DefaultClientConnectionOperator.java:137)
07-26 10:48:30.582: E/AndroidRuntime(2334):     at org.apache.http.impl.conn.AbstractPoolEntry.open(AbstractPoolEntry.java:164)
07-26 10:48:30.582: E/AndroidRuntime(2334):     at org.apache.http.impl.conn.AbstractPooledConnAdapter.open(AbstractPooledConnAdapter.java:119)
07-26 10:48:30.582: E/AndroidRuntime(2334):     at org.apache.http.impl.client.DefaultRequestDirector.execute(DefaultRequestDirector.java:360)
07-26 10:48:30.582: E/AndroidRuntime(2334):     at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:465)
07-26 10:48:30.582: E/AndroidRuntime(2334):     at com.theproblemsolver.JSONParsser.getJSONFromURI(JSONParsser.java:39)
07-26 10:48:30.582: E/AndroidRuntime(2334):     at com.theproblemsolver.ListView.onCreate(ListView.java:34)
07-26 10:48:30.582: E/AndroidRuntime(2334):     at android.app.Activity.performCreate(Activity.java:5104)
07-26 10:48:30.582: E/AndroidRuntime(2334):     at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1080)
07-26 10:48:30.582: E/AndroidRuntime(2334):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2144)
07-26 10:48:30.582: E/AndroidRuntime(2334):     ... 11 more

can somebody tell me why this error occur and what can I do to fix it. Here is the rest of my code

public class MainActivity extends Activity {

        EditText et;
        Button getanswer;

        @Override
        protected void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            setContentView(R.layout.activity_main);

            Button getanswer = (Button) findViewById(R.id.button1);
            getanswer.setOnClickListener(new OnClickListener() {

            @Override
            public void onClick(View v) {
                new asynctask().execute();
                Intent i = new Intent(MainActivity.this, ListView.class);
                startActivity(i);
            }

            //protected void launchNewActivity(){
            //startActivity(new Intent(MainActivity.this, ListView.class));


            });
        } 
    }

          class asynctask extends AsyncTask<String, Void, JSONObject> {

                 private static final String TAG_RESULTS = "ResultsSet";
                 private static final String TAG_SUBJECT = "Subject";
                 private static final String TAG_NUMANSWERS = "NumAnswers";
                 private static final String TAG_QUESTION = "Question";
                 private static final String TAG_QUESTION_CONTENT = "Content";
                 private static final String TAG_QUESTION_CHOSENANSWER = "ChosenAnswer";
                 private static final String TAG_QUESTION_ANSWERS = "Answers";
                public JSONArray json;

             @Override
             protected JSONObject doInBackground(String... params) {

                 JSONParsser jParser = new JSONParsser();

                 String URI = "http://example.com/json";

                 JSONObject json = jParser.getJSONFromURI(URI);

                 return json ;

             }{ }
                @Override
                 protected void onPostExecute(JSONObject json) {

                     JSONArray ResultsSet = null ; {
                     try {
                         ResultsSet = json.getJSONArray(TAG_RESULTS);
                    } catch (JSONException e) {
                       e.printStackTrace();
                    }
                return;
                 }}

ListView Activity

public class ListView extends ListActivity {


    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        //setContentView(R.layout.listview);


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

        JSONParsser jParser = new JSONParsser();

        String URI = "http://answers.yahooapis.com/AnswerService/V1/questionSearch?appid=4vCW8F3V34GzdMlXOS.yc2WfF5DCnCgqhK0nwCJmEFDgRwEbIgnAoEgJ0zynqOAWtQ&query=sort&type=resolved&results&output=json";;

        JSONObject json = jParser.getJSONFromURI(URI);


         final String TAG_RESULTS = "ResultsSet";
         final String TAG_SUBJECT = "Subject";
         final String TAG_NUMANSWERS = "NumAnswers";
         final String TAG_QUESTION = "Question";
         final String TAG_QUESTION_CONTENT = "Content";
         final String TAG_QUESTION_CHOSENANSWER = "ChosenAnswer";
         final String TAG_QUESTION_ANSWERS = "Answers";

                JSONArray ResultsSet = null;

        try {
           ResultsSet = json.getJSONArray(TAG_RESULTS);

           for(int i = 0; i < ResultsSet.length(); i++){
               JSONObject r = ResultsSet.getJSONObject(i);

               String Subject = r.getString(TAG_SUBJECT);
               String NumAnswers = r.getString(TAG_NUMANSWERS);

               JSONObject Question = r.getJSONObject(TAG_QUESTION);
               String Content = Question.getString(TAG_QUESTION_CONTENT);
               String ChosenAnswer = Question.getString(TAG_QUESTION_CHOSENANSWER);
               String Answers = Question.getString(TAG_QUESTION_ANSWERS);

               HashMap<String, String> map = new HashMap<String, String>();

               map.put(TAG_SUBJECT, Subject);
               map.put(TAG_NUMANSWERS, NumAnswers);

               questionList.add(map);

           }
        } catch (JSONException e) {
           e.printStackTrace();
           }

        ListAdapter adapter = new SimpleAdapter(this, questionList,
                R.layout.row,
                new String[] { TAG_SUBJECT, TAG_NUMANSWERS }, new int[] {
                R.id.Subject, R.id.NumAnswers });

        setListAdapter(adapter);


        android.widget.ListView lv = getListView();

        lv.setOnItemClickListener(new OnItemClickListener() {

            @Override
            public void onItemClick(AdapterView<?> parent, View view,
                    int position, long id) {
                String Subject = view.findViewById(R.id.Subject).getContext().toString();

                Intent i = new Intent(getApplicationContext(), SingleListItem.class);
                i.putExtra(TAG_SUBJECT, Subject);
                startActivity(i);

SingleListItem Activity

public class SingleListItem extends Activity {

    TextView subject;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        this.setContentView(R.layout.singlelistitem);

    subject = (TextView) findViewById(R.id.Subject2);

    Intent i = getIntent();
    String Subject = i.getStringExtra("TAG_SUBJECT");
    subject.setText(Subject);

    }
}

score 0 · Answer 1 · answered Jul 26 '13 at 11:26

Looks like you are using network connection in UI thread:

String URI = "http://answers.yahooapis.com/AnswerService/V1/questionSearch?appid=4vCW8F3V34GzdMlXOS.yc2WfF5DCnCgqhK0nwCJmEFDgRwEbIgnAoEgJ0zynqOAWtQ&query=sort&type=resolved&results&output=json";;
JSONObject json = jParser.getJSONFromURI(URI);

Use AsyncTask.

score 0 · Answer 2 · answered Jul 26 '13 at 11:27

0

You have problem in your Method.java file in line 511 please have a look at it.

answered Jul 26 '13 at 11:27

user2614247

75
2
10

score 0 · Answer 3 · answered Jul 26 '13 at 11:31

you should be run this one also with same way like that of Main activity class

             @Override
             protected JSONObject doInBackground(String... params) {

                 JSONParsser jParser = new JSONParsser();

                 String URI = "http://answers.yahooapis.com/AnswerService/V1/questionSearch?appid=4vCW8F3V34GzdMlXOS.yc2WfF5DCnCgqhK0nwCJmEFDgRwEbIgnAoEgJ0zynqOAWtQ&query=sort&type=resolved&results&output=json";;

                JSONObject json = jParser.getJSONFromURI(URI);

                 return json ;

             }

score 0 · Answer 4 · answered Jul 26 '13 at 11:34

From the developer.android.com

Potentially long running operations such as network or database operations, or computationally expensive calculations such as resizing bitmaps should be done in a worker thread (or in the case of databases operations, via an asynchronous request).

This is enforced to prevent Android Not Responding errors. Also from the android developer site:

In any situation in which your app performs a potentially lengthy operation, you should not perform the work on the UI thread, but instead create a worker thread and do most of the work there. This keeps the UI thread (which drives the user interface event loop) running and prevents the system from concluding that your code has frozen.

http://developer.android.com/training/articles/perf-anr.html http://developer.android.com/reference/android/os/NetworkOnMainThreadException.html

Others have already give the code fix for it.

android trouble with starting activity

4 Answers4