具有Parse.com的AutoCompleteTextView（Android）

Question

I'm new to Android in general, so I looked up the documentation for AutoCompleteTextView .

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);

I see that it's up and running with very little code.

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

I realize this is a stretch, but what would the next steps be with respect to implementing an autocomplete function based on my ParseUser table, especially as the text in the AutoCompleteTextView is changed by one character at a time?. Obviously, I wouldn't populate the USERS array with a Parse query displaying all of my users on each attempted search. How would I logically arrange such a thing?

To begin with, I'd probably include a TextChangedListener :

adapter.setNotifyOnChange(true);
    textView.addTextChangedListener(new TextWatcher() {
        public void onTextChanged(CharSequence s, int start, int before,
                int count) {
            if (count % 3 == 1) {
                new Handler().postDelayed(new Runnable() {

                    @Override
                    public void run() {
                        textview.setDropDownHeight(LayoutParams.WRAP_CONTENT);
                        adapter.clear();
                        // Run my background task here


                    }
                }, 1000);
            }
        }

        public void beforeTextChanged(CharSequence s, int start, int count,
                int after) {

        }

        public void afterTextChanged(Editable s) {

        }
    });
    textView.setOnItemSelectedListener(new OnItemSelectedListener() {

        @Override
        public void onItemSelected(AdapterView<?> adapterview, View v,
                int position, long arg3) {
            // TODO Auto-generated method stub
            searchUserTextField.setText(adapterview.getItemAtPosition(position)
                    .toString());
        }

        @Override
        public void onNothingSelected(AdapterView<?> arg0) {
            // TODO Auto-generated method stub

        }
    });

But what would I provide as the background task? What am I querying so that I'm not searching through, say, 1000 users all at once, which is how many users I have in my app currently?

Answer 1

This seems to work. It's static in the sense that it always prints out the first 100 users in your User class. I'm sure you could add a constraint that matches the first or second letters of the AutoCompleteTextView to the usernames.

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());
        }
    }
});