json - Android ListView window leak error

Question

I am having a bit of a problem on my hands and I'm going to need a little. My app keeps crashing and when I look at the stacktrace this is what I get back...

theproblemsolver.ListView has leaked window com.android.internal.policy.impl.PhoneWindow$DecorView{40d0e800 V.E..... R.....ID 0,0-234,72} that was originally added here
07-27 11:05:56.119: E/WindowManager(913): android.view.WindowLeaked: Activity com.theproblemsolver.ListView has leaked window com.android.internal.policy.impl.PhoneWindow$DecorView{40d0e800 V.E..... R.....ID 0,0-234,72} that was originally added here
07-27 11:05:56.119: E/WindowManager(913):   at android.view.ViewRootImpl.<init>(ViewRootImpl.java:354)
07-27 11:05:56.119: E/WindowManager(913):   at android.view.WindowManagerGlobal.addView(WindowManagerGlobal.java:216)
07-27 11:05:56.119: E/WindowManager(913):   at android.view.WindowManagerImpl.addView(WindowManagerImpl.java:69)
07-27 11:05:56.119: E/WindowManager(913):   at android.app.Dialog.show(Dialog.java:281)
07-27 11:05:56.119: E/WindowManager(913):   at com.theproblemsolver.ListView$LoadAllData.onPreExecute(ListView.java:85)
07-27 11:05:56.119: E/WindowManager(913):   at android.os.AsyncTask.executeOnExecutor(AsyncTask.java:586)
07-27 11:05:56.119: E/WindowManager(913):   at android.os.AsyncTask.execute(AsyncTask.java:534)
07-27 11:05:56.119: E/WindowManager(913):   at com.theproblemsolver.ListView.onCreate(ListView.java:52)
07-27 11:05:56.119: E/WindowManager(913):   at android.app.Activity.performCreate(Activity.java:5104)
07-27 11:05:56.119: E/WindowManager(913):   at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1080)
27 11:05:56.119: E/WindowManager(913):  at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2144)
07-27 11:05:56.119: E/WindowManager(913):   at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2230)
07-27 11:05:56.119: E/WindowManager(913):   at android.app.ActivityThread.access$600(ActivityThread.java:141)
07-27 11:05:56.119: E/WindowManager(913):   at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1234)
07-27 11:05:56.119: E/WindowManager(913):   at android.os.Handler.dispatchMessage(Handler.java:99)
07-27 11:05:56.119: E/WindowManager(913):   at android.os.Looper.loop(Looper.java:137)
07-27 11:05:56.119: E/WindowManager(913):   at android.app.ActivityThread.main(ActivityThread.java:5041)
07-27 11:05:56.119: E/WindowManager(913):   at java.lang.reflect.Method.invokeNative(Native Method)
07-27 11:05:56.119: E/WindowManager(913):   at java.lang.reflect.Method.invoke(Method.java:511)
07-27 11:05:56.119: E/WindowManager(913):   at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:793)
07-27 11:05:56.119: E/WindowManager(913):   at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:560)
07-27 11:05:56.119: E/WindowManager(913):   at dalvik.system.NativeStart.main(Native Method)

Can somebody please tell me what this is and what I can do to fix this..

MainActivity

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) {
            Intent i = new Intent(MainActivity.this, ListView.class);
            startActivity(i);
        }


        });
    } 
}

ListView Activity

public class ListView extends ListActivity {

    private ProgressDialog pDialog;

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

    private static String URI = "http://example.com/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;


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

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

    android.widget.ListView lv = getListView(); 

    new LoadAllData().execute();

    lv.setOnItemClickListener(new OnItemClickListener() {

    @Override
        public void onItemClick(AdapterView<?> parent, View view,int position, long id) {


        }
    });

}

    @Override
    protected void onActivityResult(int requestCode, int resultCode, Intent data) {
        super.onActivityResult(requestCode, resultCode, data);

        if (resultCode == 100) {
            Intent intent = getIntent();
            finish();
            startActivity(intent);
        }
    }

    class LoadAllData extends AsyncTask<String, String, String> {

        @Override
        protected void onPreExecute() {
            super.onPreExecute();
            pDialog = new ProgressDialog(ListView.this);
            pDialog.setMessage("Loading Data. Please wait...");
            pDialog.setIndeterminate(false);
            pDialog.setCancelable(false);
            pDialog.show();
        }

        protected String doInBackground(String... args) {

            try {
                    JSONObject json = jParser.getJSONFromURI(URI);
                    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);
                   }



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


        }


        protected void onPostExecute(String file_URI) {

            pDialog.dismiss();
            runOnUiThread(new Runnable() {
            public void run() {
                ListAdapter adapter = new SimpleAdapter(getBaseContext(), questionList,
                        R.layout.row,
                        new String[] { TAG_SUBJECT, TAG_NUMANSWERS }, new int[] {
                        R.id.Subject, R.id.NumAnswers });

                setListAdapter(adapter);



                }
            });

        }
}}

SimpleListItem

 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);

    }
}

I'm putting in two Activities that's in my project and the reason I didn't post them is because I didn't know if they are important or not

JSONParsser Activity

public class JSONParsser {

    static InputStream is = null;
    static JSONObject jObj = null;
    static String json = "";
    EditText et;

    public JSONParsser () {
    }

    public JSONObject getJSONFromURI(String URI) {

        try{
        HttpClient client = new DefaultHttpClient();
        try {
            URI website = new URI("http://example.com/json");
            HttpGet request = new HttpGet();
            request.setURI(website);
            try {
                HttpResponse response = client.execute(request);
            HttpEntity httpEntity = response.getEntity();
            is = httpEntity.getContent();

            } catch (ClientProtocolException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            } catch (IOException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
        } catch (URISyntaxException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
        return jObj;

        }finally{}

    }{

    }}

InstanceOfJSONParsser Activity

public class JSONParserInstance {

    JSONParsser jParser = new JSONParsser();

    public String URI;

    JSONObject json = jParser.getJSONFromURI(URI);


     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";

            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 NmAnswers = 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);

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

}}}

Answer 1

It appears that your AsyncTask has a strong reference to your Activity. Please consider using a static class with a WeakReference instead.

private static class StaticAsyncTask extends AsyncTask<String, String, String>() {
    private WeakReference<Activity> mActivityRef;

    private StaticAsyncTask(Activity callingActivity) {
        mActivityRef = new WeakReference<Activity>(callingActivity);
    }

    @Override
    protected String doInBackground(String... args) {
        // TODO: Do stuff
    }

    @Override
    protected void onProgressUpdate(String... progress) {
        // TODO: Do stuff
    }

    @Override
    protected void onPostExecute(String results) {
        Activity activity = mActivityRef.get();
        if (activity != null) {
            // TODO: Do stuff with my non-null activity
        }
    }
}