private void getUserImages(final String selectedUserName) {

    ParseQuery<ParseObject> query = ParseQuery.getQuery("Image");

    query.whereEqualTo("username", selectedUserName);

    query.findInBackground(new FindCallback<ParseObject>() {
        @Override
        public void done(List<ParseObject> objects, ParseException e) {
            if (e == null) {
                if (objects.size() > 0){
                    //Do something
                }
            }
        }
    });
}

public void onCreate() {
    super.onCreate();

    Parse.enableLocalDatastore(this);

    Parse.initialize(new Parse.Configuration.Builder(this)
            .applicationId("202ac01cxxxxxxxxxxa41d1136bc8a86213328b4")
            .clientKey("76b883b596xxxxxxxxxf60f9352fdb926dde46e")
            .server("http://ec2-xx-xx-xxx-59.us-east-2.compute.amazonaws.com:80/parse/")
    .build());

    ParseACL defaultACL = new ParseACL();

    defaultACL.setPublicReadAccess(true);
    ParseACL.setDefaultACL(defaultACL, true);
}