Populating a String[] Array with data from Parse.com (Android)

Question

I set up the following array adapter:

    ArrayAdapter<String> adapter = new ArrayAdapter<String>(this,
            android.R.layout.simple_dropdown_item_1line, USERS);
    AutoCompleteTextView textView = (AutoCompleteTextView)
            findViewById(R.id.searchUserTextField);
    textView.setAdapter(adapter);

For the following String[] array:

private static final String[] USERS = new String[] {
        "user1", "user2", "user3", "user4", "user5"
};

The following is the XML for my searchUserTextField . Just a typical AutoCompleteTextView :

<AutoCompleteTextView
            android:layout_width="match_parent"
            android:layout_height="65dp"
            android:background="@drawable/edittext_border"
            android:layout_gravity="top"
            android:textColor="#000000"
            android:hint="@string/search_user"
            android:id="@+id/searchUserTextField"
            android:ems="150"
            android:paddingLeft="25dp"
            android:paddingTop="10dp"
            android:paddingRight="10dp"
            android:paddingBottom="10dp"
            android:maxLines ="4"
            android:maxLength ="150"
            android:scrollHorizontally="false"
            android:typeface="sans"
            android:textSize="14sp"
            android:fontFamily="sans-serif-light"
            android:capitalize="none"
            android:inputType="textEmailAddress"
            android:gravity="center_vertical"
            android:layout_alignParentTop="true"
            android:layout_alignParentLeft="true"
            android:layout_alignParentStart="true"
            android:layout_toLeftOf="@+id/submitSearch"
            android:layout_toStartOf="@+id/submitSearch" />

So far, a very simple implementation.

I was wondering, how can I populate my USERS array with data retrieved from my User class in Parse? Basically, the use case is as follows:

1) User beings typing in AutoCompleteTextView ,

2) suggestions pop up as a function of the available usernames in my Parse.com User class,

3) user selects the name and searches for the user.

I realize this probably isn't the correct or advanced implementation for what I'm trying to accomplish, but I just want to work on this in baby steps as I'm new to Android.

My question basically boils down to, how can I dynamically populate the USERS array with a list of Users from Parse based on input to the AutoCompleteTextView ?

---

Update for Answer: I used the following in my application. I had to set this to getApplicationContext() in order for the ArrayAdapter to properly construct my custom strings array. Credit for answer goes to user hack_on below, but I had to change the context of my ArrayAdapter to get it working for my purposes.

    ParseQuery<ParseUser> userQuery = ParseUser.getQuery();
    userQuery.findInBackground(new FindCallback<ParseUser>() {
        public void done(List<ParseUser> parseUsers, ParseException e) {
            if (e == null) {
                Log.d("users", "Retrieved " + parseUsers.size());
                ParseUser[] data = parseUsers.toArray(new ParseUser[parseUsers.size()]);
                String[] strings = new String[data.length];
                for (int i = 0; i < data.length; i++) {
                    strings[i] = data[i].getString(ParseConstants.KEY_USERNAME);
                }
                // Test to see if it was correctly printing out the array I wanted.
                // System.out.println(Arrays.toString(strings));
                ArrayAdapter<String> adapter = new ArrayAdapter<String>(getApplicationContext(), android.R.layout.simple_dropdown_item_1line, strings);
                AutoCompleteTextView textView = (AutoCompleteTextView) findViewById(R.id.searchUserTextField);
                if(parseUsers.size() < 40) textView.setThreshold(1);
                else textView.setThreshold(2);
                textView.setAdapter(adapter);
            } else {
                Log.d("users", "Error: " + e.getMessage());
            }
        }
    });

Answer 1

One of the (not accepted) answers to this question: Dynamically updating an AutoCompleteTextView adapter shows how to use a filter in the adapter to update the suggestions dynamically. You would have to implement the "autocomplete()" method and in your case return results from Parse.

EDIT : By dynamically populate, Op was asking to run a query before display of the list, not in response to user typing in the list.

ParseQuery<ParseUser> userQuery = ParseUser.getQuery();
    userQuery.findInBackground(new FindCallback<ParseUser>() {
        public void done(List<ParseUser> parseUsers, ParseException e) {
            if (e == null) {
                Log.d("score", "Retrieved " + parseUsers.size());
                ParseUser[] data = parseUsers.toArray(new ParseUser[parseUsers.size()]);
                String[] strings = new String[data.length];
                for (int i=0; i<data.length; i++) {
                    strings[i] = data[i].getString(ParseConstants.KEY_USER_REAL_NAME);
                }
                ArrayAdapter<String> adapter = new ArrayAdapter<String>(this, android.R.layout.simple_dropdown_item_1line, strings);
                AutoCompleteTextView textView = (AutoCompleteTextView)
                        findViewById(R.id.searchUserTextField);
                if(parseUsers.size() < 40) textView.setThreshold(1);
                else textView.setThreshold(2);
                textView.setAdapter(adapter);
            } else {
                Log.d("score", "Error: " + e.getMessage());
            }
        }
    });

Answer 2

Can't I do something like this?

            ParseQuery<ParseUser> userQuery = ParseUser.getQuery();
    userQuery.findInBackground(new FindCallback<ParseUser>() {
        public void done(List<ParseUser> parseUsers, ParseException e) {
            if (e == null) {
                Log.d("score", "Retrieved " + parseUsers.size());
                ParseUser[] data = parseUsers.toArray(new ParseUser[parseUsers.size()]);
                ArrayAdapter<String> adapter = new ArrayAdapter<String>(this, android.R.layout.simple_dropdown_item_1line, data);
                AutoCompleteTextView textView = (AutoCompleteTextView)
                        findViewById(R.id.searchUserTextField);
                if(parseUsers.size() < 40) textView.setThreshold(1);
                else textView.setThreshold(2);
                textView.setAdapter(adapter);
            } else {
                Log.d("score", "Error: " + e.getMessage());
            }
        }
    });

I'm just getting an error on the following line:

ArrayAdapter<String> adapter = new ArrayAdapter<String>(this, android.R.layout.simple_dropdown_item_1line, data);

It says "Cannot resolve constructor 'ArrayAdapter(com.Parse.FindCallback, int, com.parse.ParseUser[])'