Develop Reference

How to bind live data to array adapter android

I have a simple application while I'm trying to understand android/room. I would like to have my query from room to be placed into my list view.
PersonDao.class
#Query("Select name from People limit 3")
LiveData<List<String>> getThreeNames();
AvtivityMain.class
private ArrayAdapter<String> adapter;
private PersonDatabase db;
private EditText age;
private EditText name;
Person person;
private DatabaseRepository rDb;
private PersonViewModel personViewModel;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
name = findViewById(R.id.name);
age = findViewById(R.id.age);
adapter = new ArrayAdapter<String>(this, android.R.layout.simple_list_item_1);
ListView lvPerson = findViewById(R.id.lv3Poeple);
lvPerson.setAdapter(adapter);
personViewModel = ViewModelProviders.of(this).get(PersonViewModel.class);
}
public void addPerson(View view){
int sAge = Integer.parseInt(age.getText().toString());
String sName = name.getText().toString();
person = new Person(sName, sAge);
personViewModel.insert(person);
System.out.println(personViewModel.getmAllPeople());
System.out.println(personViewModel.getm3People());
//List<String> names = personViewModel.getm3People();
//adapter.add(personViewModel.getm3People());
}
I have commented out the code I am having problems with. I want to be able to use my query from PersonDao and have my list view show 3 names from my Room database.

You need to do a few things, the first is make sure your adapter can take new input. I would suggest creating your own custom one. When you do create it, be sure to include a method that takes your person strings as input and notifies the adapter of the change, like so:
//you need to add an update method to your adapter, so it can change it's data as your
//viewmodel data changes, something like this:
public void setPersons(List<String> personNames) {
//myPersons should be a variable declared within your adapter that the views load info from
myPersons = personNames;
notifyDataSetChanged();
}
Then in your activity you should set the Adapter as a global variable so it can be accessed by multiple methods, such as your view model observer method and it's initial setup in onCreate().
//need to set up adapter variable to access in other methods to keep view model observer
//off the main thread
private ArrayAdapter myAdapter;
After that you can set up the following observer method for your ViewModel (assuming you created the ViewModel Class properly with a return method called getThreeNames() and that isn't just within your DAO as you showed above.
//set up the view model observer to be off the main thread so it isn't tied to your main
//activity lifecyle (which is the whole point/beauty of the ViewModel), you can call this
//method in your onCreate() method and should stay until onDestroy() is called
private void setupPersonViewModel() {
PersonViewModel viewModel
= ViewModelProviders.of(this).get(PersonViewModel.class);
viewModel.getThreeNames().observe(this, new Observer<List<String>>() {
#Override
public void onChanged(#Nullable List<String> persons) {
//so you can see when your app does this in your log
Log.d(TAG, "Updating list of persons from LiveData in ViewModel");
mAdapter.setPersons(persons);
}
});
}
Hope that answers your question. Let me know if you need any further clarification.

Best way to change data on FirebaseRecyclerAdapter

currently I am using FirebaseRecyclerAdapter to represent data on a RecyclerView using the following Firebase query:
postsQuery = mDatabase.child("lists_new”).orderByKey().limitToFirst(10);
My RecyclerView has a header with 2 buttons: New List, Old List.
New list is loaded by default, and my question is, when the user taps the Old List button, what is the most efficient way to replace the new list with old list.
The Firebase query for the old list looks like this:
postsQuery = mDatabase.child("lists_old”).orderByKey().limitToFirst(10);
Note: both new list and the old list has the same data types, i.e. they share the same Java POJO class and the the same layout.

You will need a new adapter and attach that to the same RecyclerView.
So after constructing the new query, you create a new adapter and attach it to the view:
adapter = new FirebaseRecyclerAdapter<Chat, ChatHolder>(
Chat.class, android.R.layout.two_line_list_item, ChatHolder.class, postsQuery) {
recyclerView.setAdapter(adapter);

I have a similar need and a similar solution except I am calling cleanup() on the adapter before new'ing up another one. I am thinking without calling cleanup() it will create a leak of adapters and/or listeners?
In onActivityCreated() in my Fragment I am calling a method in the Fragment that manages the recycler view. Call the method to initialize or refresh the list and pass in a leaf node name. If the adapter is not null then call cleanup(). Create a new database reference by concatenating a new leaf node with the parent reference, new-up a new adapter and set it.
I call cleanup() in onDestroy() as well, per usual.
It works fine so far though I've only tested using the emulator and a small data set.
#Override
public void onActivityCreated(#Nullable Bundle savedInstanceState) {
super.onActivityCreated(savedInstanceState);
refreshList(newLeafNode);
}
#Override
public void onDestroy() {
super.onDestroy();
mRVAdapter.cleanup();
}
protected void refreshList(String newLeafNode) {
if (mRVAdapter != null) {
mRVAdapter.cleanup();
}
DatabaseReference newDbRef = mParentRef.child(newLeafNode);
mRVAdapter = new FirebaseRecyclerAdapter<String, MyViewHolder>(String.class, R.layout.single_row, MyViewHolder.class, newDbRef) {
#Override
protected void populateViewHolder(MyViewHolder viewHolder, String model, int position) {
viewHolder.setImage(model);
}
};
mMyRV.setAdapter(mRVAdapter);
}

ParseQueryAdapter; using class in Android

I feel like a broken record.
After many attempts, I have failed at getting a listview through Parse data to display a specific set of information.
Here is my model...this is all data from users:
#ParseClassName("Midwifefirm")
public class Midwifefirm extends ParseObject {
public Midwifefirm() {
// A default constructor is required.
}
//practice name
public String getPracticeName() {
return getString("practicename");
}
public void setPracticeName(String practicename) {
put("practicename", practicename);
}
//education
public String getEducation() {
return getString("education");
}
public void setEducation(String education) {
put("education", education);
}
//years in practice
public String getYearsinPractice() {
return getString("yearsinpractice");
}
public void setYearsinPractice(String yearsinpractice) {
put("yearsinpractice", yearsinpractice);
}
//practice philosophy
public String getPracticePhilosophy() {
return getString("practicephilosophy");
}
public void setPracticePhilosophy(String practicephilosophy) {
put("practicephilosophy", practicephilosophy);
}
I have this adapter; I am wondering what to place in the query section, as I just want to pull the data into the ListView that is defined in the data model:
public class CustomMidwifeAdapter extends ParseQueryAdapter<Midwifefirm> {
public CustomMidwifeAdapter(Context context) {
super(context, new ParseQueryAdapter.QueryFactory<Midwifefirm>() {
public ParseQuery<Midwifefirm> create() {
// Here we can configure a ParseQuery to display
// only top-rated meals.
ParseQuery query = new ParseQuery("Midwives");
return query;
}
});
}
#Override
public View getItemView(Midwifefirm midwifefirm, View view, ViewGroup parent) {
if (view == null) {
view = View.inflate(getContext(), R.layout.activity_midwife_result_list, null);
}
//use midwifefirm as item view/list
super.getItemView(midwifefirm, view, parent);
// find in layout the practice name
TextView titleTextView = (TextView) view.findViewById(R.id.practicename);
//in the midwifefirm data model, call getPracticename
titleTextView.setText(midwifefirm.getString("practicename"));
// Add education view
TextView EducationView = (TextView) view.findViewById(R.id.education);
EducationView.setText(midwifefirm.getString("education"));
// Add yearsexperience view
TextView ExperienceView = (TextView) view.findViewById(R.id.yearsinpractice);
ExperienceView.setText(midwifefirm.getString("yearsinpractice"));
//Add practice philosophy view
TextView PracticePhilosophyView = (TextView) view.findViewById(R.id.practicephilosophy);
PracticePhilosophyView.setText(midwifefirm.getString("practicephilosophy"));
return view;
}
}
And here is the Main Activity:
public class MidwifeResultList extends ListActivity {
private ParseQueryAdapter<ParseObject> mainAdapter;
private CustomMidwifeAdapter midwifeListAdapter;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
//initialize main ParseQueryAdapter
mainAdapter = new ParseQueryAdapter<ParseObject>(this, Midwifefirm.class);
//which keys in Midwife object
mainAdapter.setTextKey("practicename");
mainAdapter.setTextKey("education");
mainAdapter.setTextKey("yearsinpractice");
mainAdapter.setTextKey("practicephilosophy");
// Initialize the subclass of ParseQueryAdapter
midwifeListAdapter = new CustomMidwifeAdapter(this);
// Default view is all meals
setListAdapter(mainAdapter);
}
Every time I run this, I get no results.
Thanks in advance for any help
Michael

I can tell you why I think it fails now and I can tell you why I'm very sure it will fail after you sort out the current issue.
It seems that you're trying to use different classes
#ParseClassName("Midwifefirm")
public class Midwifefirm extends ParseObject {
and
ParseQuery query = new ParseQuery("Midwives");
You need to be consistent and use the same name. Either use Midwives or Midwifefirm for both. Let's assume you picked the latter. You're also saying
all that is stored in the user table...wasn't sure if I needed to create new tables.
The query above wants to get all entries of type Midwives. If there's no such type, it'll return nothing. So you have two options:
In you Parse dashboard, reate a class Midwifefirm (don't forget to update the String inside #ParseClassName above) and store your Midwifefirm data in there. You don't need to change your query for this.
Add a column to your ParseUser class, such as type, that you can set to Midwifefirm or whatever if that user is a Midwifefirm or whatever. Then in your query you need to add:
ParseQuery query = new ParseQuery("Midwives");
query.whereEquals("type", "Midwifefirm");
I greatly prefer the former.
Anyway, once your done that, the issue is that you're not using a custom view for this. You're relying on the one provided by Android by default for ListActivity. I am fairly sure it doesn't have any of the fields you're after, so you should create a custom view for this, then at the top of onCreate in your Activity make sure you use it
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.my_custom_view);
By the way, the following are redundant if you populate then in getItemView anyway:
mainAdapter.setTextKey("practicename");
mainAdapter.setTextKey("education");
mainAdapter.setTextKey("yearsinpractice");
mainAdapter.setTextKey("practicephilosophy");
One final advice: if you're still having issues, set breakpoints and do some investigations first. What you need to check is:
Whether you get anything at all from Parse when you do your query. Your adapter has an useful addOnQueryLoadListener that you may use to check whether anything's been retrieved at all.
If stuff is retrieved successfully, you need to check whether the list view is populated correctly. Again, use breakpoints, this time in getItemView maybe.

I'm going to do a wild guess here using the lovely brainwrecking API help of Parse.com about ParseQueryAdapters
Before continuing, may I mind you that my experience with ParseQueryAdapters is a minimum but I think I have a basic knowledge about them + I have some experience with Parse on its own. ANYHOW,
As an example they use both these
final ParseQueryAdapter adapter = new ParseQueryAdapter(this, "Midwives");
adapter.setTextKey("name");
ListView listView = (ListView) findViewById(R.id.listview);
listView.setAdapter(adapter);
and
// Instantiate a QueryFactory to define the ParseQuery to be used for fetching items in this
// Adapter.
ParseQueryAdapter.QueryFactory<ParseObject> factory =
new ParseQueryAdapter.QueryFactory<ParseObject>() {
public ParseQuery create() {
ParseQuery query = new ParseQuery("Midwives");
return query;
}
};
// Pass the factory into the ParseQueryAdapter's constructor.
ParseQueryAdapter<ParseObject> adapter = new ParseQueryAdapter<ParseObject>(this, factory);
adapter.setTextKey("name");
// Perhaps set a callback to be fired upon successful loading of a new set of ParseObjects.
adapter.addOnQueryLoadListener(new OnQueryLoadListener<ParseObject>() {
public void onLoading() {
// Trigger any "loading" UI
}
public void onLoaded(List<ParseObject> objects, ParseException e) {
// Execute any post-loading logic, hide "loading" UI
}
});
// Attach it to your ListView, as in the example above
ListView listView = (ListView) findViewById(R.id.listview);
listView.setAdapter(adapter);
To start of, the reason why I think nothing is loading inside your list has to do with a little mixup between the initilization of your ParseQueryAdapter and your custom adapter.
You configure the basic adapter, and also initialize a custom adapter but you don't do anything with the custom adapter, tho the custom adapter seems to contain the logics to load your data model.
I think what you're looking for is something like this:
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
//initialize main ParseQueryAdapter
mainAdapter = new CustomMidwifeAdapter<ParseObject>(this);
//which keys in Midwife object
mainAdapter.setTextKey("practicename");
mainAdapter.setTextKey("education");
mainAdapter.setTextKey("yearsinpractice");
mainAdapter.setTextKey("practicephilosophy");
// Default view is all meals
setListAdapter(mainAdapter);
}
All you need to pass is the context (aka "this"), and the constructor of your custom class will handle the factory internal
super(context, new ParseQueryAdapter.QueryFactory<Midwifefirm>() {
public ParseQuery<Midwifefirm> create() {
// Here we can configure a ParseQuery to display
// only top-rated meals.
ParseQuery query = new ParseQuery("Midwives");
return query;
}
});
Tho to be honest since you do:
new ParseQueryAdapter<ParseObject>(this, Midwifefirm.class);
I wonder if you'd need to change your "QueryFactory" to
super(context, new ParseQueryAdapter.QueryFactory<Midwifefirm>() {
public ParseQuery<Midwifefirm> create() {
// Here we can configure a ParseQuery to display
// only top-rated meals.
ParseQuery query = new ParseQuery(MidWifefirm.class);
return query;
}
});
Where you pass a class to the the query rather than the tableName, but I could be wrong on that one.
Either way I hope this has helped in some way!

Android ParseQueryAdapter notifyDataSetChanged does not work

Using latest Parse library v1.5.1
Thanks to the update now I can do:
ParseQueryAdapter<ParseObject> mAdapter = new ParseQueryAdapter<ParseObject>(MainActivity.this, new ParseQueryAdapter.QueryFactory<ParseObject>() {
#Override
public ParseQuery<ParseObject> create() {
ParseQuery<ParseObject> query = new ParseQuery<ParseObject>(ParseObject.class);
query.fromLocalDatastore();
return query;
}
});
mListView.setAdapter(mAdapter);
Now I have some pinned objects and they appear correctly, but when I unpin them like so:
//Some ParseObject in the above adapter
object.unpinInBackground(new DeleteCallback() {
#Override
public void done(ParseException e) {
if(e == null) {
//I beleive this would be the correct approach.
mAdapter.notifyDataSetChanged();
}
}
});
Naturally I want that item to disappear from the corresponding ListView, but it doesn't. But say I go back to a different activity and revisit this activity, the ListView is displayed properly without the recently unpinned object.
Is this a bug? If not what am I doing wrong?

I have the same problem) I solve it with invoke method ParseQueryAdapter.loadObjects().

You can try mAdapter.remove(object) before calling notifyDataSetChanged();
unpinInBackground removes the object from the database. Probably the adapter has a local copy of the object.
Looks like there is no remove method in ParseQueryAdapter.
Here is an response from official source:
Since a ParseQueryAdapter is designed to always show the results of a
ParseQuery, you would need to use an API request to reload the query.
https://www.parse.com/questions/delete-a-object-using-parsequeryadapter

Update the Arraylist automatically when the data of the list is updated

While inserting my listview gets refreshed automatically but not update when the item in the listview is updated. It only updates on database. I can see the listview is updated when I close the application and open again, or come back from previous activity.
I found some discussion related to my problem. Like: Refresh ListView with ArrayAdapter after editing an Item . Her I found that make a new method to populate the Listview and call it in the onResume method of your activity.
And the problem has been solved using this. But I do not get how to make new method mentioned like there. Could anybody help me to make it understandable?
My code in activity class:
personNamesListView = (ListView) findViewById(R.id.traineeslist);
traineeListAdapter = new ArrayAdapter<Trainee>(this,
android.R.layout.simple_list_item_1,
currentTraining.getTraineeArrayList());
personNamesListView.setAdapter(traineeListAdapter);
protected void onResume() {
super.onResume();
}
And this way I populated my personNamesListView using method stringToString() in model class;
public void loadTraineeList() {
DatabaseHelper db = DatabaseHelper.getInstance();
this.traineeArrayList = new ArrayList <Trainee>();
Cursor cursor = db.select("SELECT * FROM person p JOIN attendance a ON p._id = a.person_id WHERE training_id="+Integer.toString(this.getId())+";");
while (cursor.moveToNext()) {
Trainee trainee = new Trainee();
trainee.setID(cursor.getInt(cursor.getColumnIndex(DatabaseHelper.PERSON_ID)));
trainee.setFirstname(cursor.getString(cursor.getColumnIndex(DatabaseHelper.PERSON_FIRSTNAME)));
trainee.setLastname(cursor.getString(cursor.getColumnIndex(DatabaseHelper.PERSON_LASTNAME)));
trainee.setJobTitle(cursor.getString(cursor.getColumnIndex(DatabaseHelper.PERSON_JOBTITLE)));
trainee.setEmail(cursor.getString(cursor.getColumnIndex(DatabaseHelper.PERSON_EMAIL)));
trainee.setCompany(cursor.getString(cursor.getColumnIndex(DatabaseHelper.PERSON_COMPANY)));
trainee.setDepartment(cursor.getString(cursor.getColumnIndex(DatabaseHelper.PERSON_DEPARTMENT)));
trainee.setBadgeNumber(cursor.getString(cursor.getColumnIndex(DatabaseHelper.PERSON_BADGE)));
// Pass to the arraylist
this.traineeArrayList.add(trainee);
}
}
public ArrayList<Trainee> getTraineeArrayList() {
return traineeArrayList;
}
public void setTraineeArrayList(ArrayList<Trainee> traineeArrayList) {
this.traineeArrayList = traineeArrayList;
}
I insert and Update data into database into one method:
public void storeToDB() {
DatabaseHelper db = DatabaseHelper.getInstance();
db.getWritableDatabase();
if (this.id == -1) {
// Person not yet stored into Db => SQL INSERT
// ContentValues class is used to store a set of values that the
// ContentResolver can process.
ContentValues contentValues = new ContentValues();
// Get values from the Person class and passing them to the
// ContentValues class
contentValues.put(DatabaseHelper.PERSON_FIRSTNAME, this
.getFirstname().trim().toUpperCase());
contentValues.put(DatabaseHelper.PERSON_LASTNAME, this
.getLastname().trim().toUpperCase());
contentValues.put(DatabaseHelper.PERSON_JOBTITLE, this
.getJobTitle().trim().toUpperCase());
contentValues.put(DatabaseHelper.PERSON_EMAIL, this.getEmail());
contentValues.put(DatabaseHelper.PERSON_COMPANY, this.getCompany()
.trim().toUpperCase());
contentValues.put(DatabaseHelper.PERSON_DEPARTMENT, this
.getDepartment().trim().toUpperCase());
contentValues.put(DatabaseHelper.PERSON_BADGE, this
.getBadgeNumber().trim().toUpperCase());
// here we insert the data we have put in values
this.setID((int) db.insert(DatabaseHelper.TABLE_PERSON,
contentValues));
} else {
// Person already existing into Db => SQL UPDATE
ContentValues updateTrainee = new ContentValues();
updateTrainee.put(DatabaseHelper.PERSON_FIRSTNAME, this
.getFirstname().trim().toUpperCase());
updateTrainee.put(DatabaseHelper.PERSON_LASTNAME, this
.getLastname().trim().toUpperCase());
updateTrainee.put(DatabaseHelper.PERSON_JOBTITLE, this
.getJobTitle().trim().toUpperCase());
updateTrainee.put(DatabaseHelper.PERSON_EMAIL, this.getEmail());
updateTrainee.put(DatabaseHelper.PERSON_COMPANY, this.getCompany()
.trim().toUpperCase());
updateTrainee.put(DatabaseHelper.PERSON_DEPARTMENT, this
.getDepartment().trim().toUpperCase());
updateTrainee.put(DatabaseHelper.PERSON_BADGE, this
.getBadgeNumber().trim().toUpperCase());
db.update(DatabaseHelper.TABLE_PERSON, updateTrainee,
DatabaseHelper.PERSON_ID+"= ?", new String[]{Integer.toString(this.getId())});
System.out.println("Data updated");
}
}

You should call traineeListAdapter.notifyDataSetChanged() whenever you update your ArrayList representing the items in the ListView.

There's a similar question here that can give you some help.
Although I've accomplished something similar using
yourlistview.invalidateViews()
after changing the data to show in the listview
when notifyDataSetChanged() didn't work.
EDIT:
After making all the operations in the data that I want to show i just set the adapter and try to refresh my listview by calling invalidateViews().
selectedStrings = new ArrayList<String>(typeFilterStrings);
adapter.setArrayResultados(selectedStrings);
listTypeFilter.invalidateViews();
It's not obligatory to set the adapter again in my case worked.

use like this:
Create an instance of your custom adapter, so you can use it anywhere you like...
public class ScoreList extends SherlockFragmentActivity {
private ListView listViewScore;
private ScoreListAdapter adapter;
static List<Score> listScore = new ArrayList<Score>();
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.score_list);
ctx = this;
listScore = dbh.getAllScores();
listViewScore = (ListView) findViewById(R.id.score_list);
adapter = new ScoreListAdapter(ctx, R.layout.score_row_item, listScore);
listViewScore.setAdapter(adapter);
((BaseAdapter) listViewScore.getAdapter()).notifyDataSetChanged();
}
}
By the way, if your listScore array is already loaded, then you do not need to use
adapter.notifyDatasetChanged();