title: How to get a List<ParseUser> of Parse usernames?
body: <p>I have this code on my activity:</p>
  
  <pre><code>ParseQuery&lt;ParseUser&gt; query = ParseUser.getQuery();
      query.findInBackground(new FindCallback&lt;ParseUser&gt;() {
          public void done(List&lt;ParseUser&gt; userList, ParseException e) {
              if (e == null) {
                  Log.d("score", "Retrieved " + userList.size() + " scores");
                  for (int i = 0; i &lt; userList.size(); i++) {
                      friends.add(userList.toString());
                  }
                  aAdapter = new ArrayAdapter&lt;String&gt;(context, android.R.layout.simple_dropdown_item_1line, friends);
                  friendChooser.setAdapter(aAdapter);
              } else {
                  Log.d("score", "Error: " + e.getMessage());
              }
          }
      });
  </code></pre>
  
  <p>The problem is that this array contains all of columns, when I want to get only the "username" field. How can I get only the "username" field?
  <br>
  Another problem is that because that in the User table there is a boolean field called "emailVerified", and aAdapter is an <code>ArrayAdapter&lt;String</code> it cannot have a boolean inside, so the app crashed. So again, how can I get only the "username" field?</p>
  
  <p>Logcat of crash:</p>
  
  <pre><code>java.lang.NullPointerException: Attempt to invoke interface method 'boolean java.util.List.add(java.lang.Object)' on a null object reference
          at com.intap.tof.GameActivity$3.done(GameActivity.java:189)
          at com.intap.tof.GameActivity$3.done(GameActivity.java:184)
          at com.parse.ParseTaskUtils$2$1.run(ParseTaskUtils.java:107)
          at android.os.Handler.handleCallback(Handler.java:739)
          at android.os.Handler.dispatchMessage(Handler.java:95)
          at android.os.Looper.loop(Looper.java:145)
          at android.app.ActivityThread.main(ActivityThread.java:5832)
          at java.lang.reflect.Method.invoke(Native Method)
          at java.lang.reflect.Method.invoke(Method.java:372)
          at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1399)
          at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1194)
  </code></pre>
  
  <p>Logcat on crash with @MarcoBatista's answer:</p>
  
  <pre><code>java.lang.NullPointerException: Attempt to invoke virtual method 'java.lang.Object android.content.Context.getSystemService(java.lang.String)' on a null object reference
          at android.widget.ArrayAdapter.init(ArrayAdapter.java:310)
          at android.widget.ArrayAdapter.&lt;init&gt;(ArrayAdapter.java:153)
          at com.intap.tof.GameActivity$3.done(GameActivity.java:192)
          at com.intap.tof.GameActivity$3.done(GameActivity.java:184)
          at com.parse.ParseTaskUtils$2$1.run(ParseTaskUtils.java:107)
          at android.os.Handler.handleCallback(Handler.java:739)
          at android.os.Handler.dispatchMessage(Handler.java:95)
          at android.os.Looper.loop(Looper.java:145)
  </code></pre>
  
  <p>The error lines:
  <br>
  GameActivity.java:192 - <code>friendChooser.setAdapter(aAdapter);</code>
  <br>
  GameActivity.java:184 - <code>public void done(List&lt;ParseUser&gt; userList, ParseException e) {</code></p>
  
  <p>For you:
  <br>
  <code>aAdapter</code> is an <code>ArrayAdapter&lt;String&gt;</code>.
  <br>
  <code>friendChooser</code> is a <code>MultiAutoCompleteTextView</code>.
  <br>
  <code>friends</code> is a <code>List&lt;String&gt;</code>.
  <br>
  <code>userList</code> is a <code>List&lt;ParseUser&gt;</code>.</p>