Android : Window Manager : android view window leaked : <p>Right after I fix my first problem this one comes up :( please help me fix it..</p>

<blockquote>
  <p>03-02 12:47:02.785    9439-9439/com.ucu.ccs.classrecord
  E/WindowManager﹕ android.view.WindowLeaked: Activity
  com.ucu.ccs.classrecord.Login has leaked window
  com.android.internal.policy.impl.PhoneWindow$DecorView{6d17cc4
  V.E..... R......D 0,0-1002,348} that was originally added here
              at android.view.ViewRootImpl.(ViewRootImpl.java:465)
              at android.view.WindowManagerGlobal.addView(WindowManagerGlobal.java:277)
              at android.view.WindowManagerImpl.addView(WindowManagerImpl.java:69)
              at android.app.Dialog.show(Dialog.java:312)
              at com.ucu.ccs.classrecord.Login$AttemptLogin.onPreExecute(Login.java:158)
              at android.os.AsyncTask.executeOnExecutor(AsyncTask.java:587)
              at android.os.AsyncTask.execute(AsyncTask.java:535)
              at com.ucu.ccs.classrecord.Login.isOnline(Login.java:113)
              at com.ucu.ccs.classrecord.Login$1.onClick(Login.java:73)
              at android.view.View.performClick(View.java:5197)
              at android.view.View$PerformClick.run(View.java:20926)
              at android.os.Handler.handleCallback(Handler.java:739)
              at android.os.Handler.dispatchMessage(Handler.java:95)
              at android.os.Looper.loop(Looper.java:145)
              at android.app.ActivityThread.main(ActivityThread.java:5942)
              at java.lang.reflect.Method.invoke(Native Method)
              at java.lang.reflect.Method.invoke(Method.java:372)
              at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1399)
              at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1194)</p>
</blockquote>

<p>here is my code:</p>

<pre><code>buttonLogin.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                String instructor_id = editUser.getText().toString().trim();
                String password = editPass.getText().toString().trim();

                SharedPreferences preferences = getSharedPreferences("MyApp", MODE_PRIVATE);
                preferences.edit().putString("password", password).commit();
                preferences.edit().putString("inst_id", instructor_id).commit();

                if (editUser.getText().toString().equals("") || editPass.getText().toString().equals("")){
                    Toast.makeText(getApplicationContext(),"Please enter Instructor ID and Password", Toast.LENGTH_LONG).show();
                }else {
                    isOnline();
                }

            }
        });

public boolean isOnline(){
        ConnectivityManager connectivityManager = (ConnectivityManager) getSystemService(Context.CONNECTIVITY_SERVICE);
        NetworkInfo networkInfo = connectivityManager.getActiveNetworkInfo();
        if (networkInfo != null &amp;&amp; networkInfo.isConnectedOrConnecting()){
            new AttemptLogin().execute();
        }else {
            checkInternet();
        }
        return false;
    }

class AttemptLogin extends AsyncTask&lt;String, String, String&gt; {
        boolean failure = false;
        String inst_id = editUser.getText().toString();
        String password = editPass.getText().toString();

        @Override
        protected void onPreExecute() {
            super.onPreExecute();
            pDialog = new ProgressDialog(Login.this);
            pDialog.setMessage("Attempting login...");
            pDialog.setIndeterminate(false);
            pDialog.setCancelable(true);
            pDialog.show();
        }

        @Override
        protected String doInBackground(String... params) {
            int success;
            try{
                List&lt;NameValuePair&gt; mList = new ArrayList&lt;NameValuePair&gt;();
                mList.add(new BasicNameValuePair("instructor_id", inst_id));
                mList.add(new BasicNameValuePair("password", password));

                Log.d("request!", "starting");

                JSONObject json = jsonParser.makeHttpRequest(LOGIN_URL, "POST", mList);
                Log.d("Login attempt", json.toString());

                success = json.getInt(TAG_SUCCESS);
                if (success == 1) {
                    Log.d("Login Successful!", json.toString());
                    Intent i = new Intent(Login.this, MainActivity.class);
                    startActivity(i);
                    //finish();
                    return json.getString(TAG_MESSAGE);
                }else{
                    Log.d("Login Failure!", json.getString(TAG_MESSAGE));
                    return json.getString(TAG_MESSAGE);
                }

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

        @Override
        protected void onPostExecute(String s) {
            super.onPostExecute(s);
            session.setLogin(true);
            pDialog.dismiss();
            if (s != null){
                Toast.makeText(getApplicationContext(), s, Toast.LENGTH_SHORT).show();
            }
        }
    }
</code></pre>
