New to Android, I got a simple application with spinners and associated ArrayAdapters working: when things get selected, I seem to be able and trigger some calculations. I am then saving the current selected item.
At some point, I retrieve the saved value, and want to position the spinner at that value: basically setPosition() the spinner to that object.
I have found lots of tutorials with the same format I have: use the getPosition() on the ArrayAdapter, and pass in the object you are looking for... Trouble is, it keeps returning -1 (not found).
Debugging, I have verified that the object I pass is not null, and so is the ArrayAdapter, and also the ArrayAdapter getCount returns me the items it should have (so it's not empty).
I'm at loss. Appreciate any... pointers? :-)
/* ArrayAdapter class looks like this*/
public class MyAdapter extends ArrayAdapter<MyClass> {
// Constructor
MyAdapter(#NonNull Context context, int resource, #NonNull List<MyClass> objects) {
super(context, resource, objects);
}
}
/* Fragment looks like this*/
final MyAdapter mAdapter = new MyAdapter(
requireActivity(),
android.R.layout.simple_spinner_item,
objects);
Spinner mySpinner = fragment_view.findViewById(R.id.my_spinner);
mySpinner.setAdapter(mAdapter);
// assume I have one "object" of MyClass,
// and want to search for it in "MyAdapter"
int spinnerPosition = mAdapter.getPosition(objectToBeFound); // returns -1
mySpinner.setSelection(spinnerPosition);
Adapter internally works with List
public int getPosition(#Nullable T item) {
return mObjects.indexOf(item);
}
so getPosition internally depends upon List#indexOf(T) and which relies on equals method
(o==null ? get(i)==null : o.equals(get(i)))
so you are getting -1 because you haven't implemented equals and hashcode method properly in MyClass so implement both methods and you will be able to get the precise index.
Referene:
Use Auto Generate
difference between equals() and hashCode()
I want to know if is it a good way to use the same adapter for more than one listview.
in my code i have many listviews and each one contains the same UL components like imageview and textview, so is it good to use `MyAdapter extends BaseAdapter` for each of them ? or it is better to make adapter for each one?
if i have to use one adapter, how to handle the different onclick actions for the button, imageview and textview for each listview ?
class MyAdapter extends BaseAdapter {
public MyAdapter() {
}
#Override
public int getCount() {
// TODO Auto-generated method stub
return data.size();
}
#Override
public Object getItem(int position) {
// TODO Auto-generated method stub
return position;
}
#Override
public long getItemId(int position) {
// TODO Auto-generated method stub
return position;
}
#Override
public View getView(final int position, View convertView, ViewGroup parent) {
// TODO Auto-generated method stub
return null;
}
}
It will make no difference resource-wise either way, as you will have to create a new instance of the adapter for each listview anyway. But trying to incorporate the features of two different adapters into one even just sounds overly complex. I would say for clarity of design, just make two different adapters. It'll make your life so much easier in the long run when it comes to debugging as well.
Keep in mind this is when the behaviors of each list are different, if the lists are supposed to function the same go ahead and use the same adapter for each.
Are you talking about reusing the instance of the adapter or its class? The class can be reused ad infinatum.
The instance, however, is safer not to be reused. The reason for this is you will likely have collsions or artifacts from the previous AdapterView. Adapter creation is menial, so why not just be safe and create a new one for each AdapterView?
This is a really good question I often struggle with. Seems so unnecessary duplicating so much adapter code just for different actions. I still struggle with this questions as a design issue, so my answer is not intended to provide an answer on that. However, for the part of the question about reusing the adapter or not, what I do if I wish to reuse a list/adapter is this:
For each type of list I create a global constant value to act as an identifier for that type of list. When I create a new instance of the adapter I supply the requestId/listTypeId to the adapter:
//first i create the constants somewhere globally
TYPE_ID_A = 0;
TYPE_ID_B = 1;
TYPE_ID_C = 2
//then i feed them to my adapter and set the clickListener on my list
mList.setAdapter(new MyListAdapter(mContext, listData, TYPE_ID_A));
mList.setOnItemClickListener(this);
In my adapter I set this typeId as a member variable and further then create a public function to return this id:
public class MyListAdapter extends ArrayAdapter<JSONArray> {
private final Context mContext;
private final JSONArray mItems;
private final int mListType;
//assign the values in the constructor of the adapter
public SearchListAdapter(Context context, JSONArray items, int listType) {
super(context, R.layout.item_filter_list);
mItems = items;
mContext = context;
mListType = listType;
}
//function to return the list id
public int getListType(){
return mListType;
}
}
Finally, inside my onClick listener I call this function inside my adapter to return the listTypeId which I then compare the global constants to identify what do to further:
#Override
public void onItemClick(AdapterView<?> adapterView, View view, int i, long l) {
MyListAdapter adapter = (MyListAdapter) adapterView.getAdapter();
int listType = adapter.getListType(); //get the listTypeId now
//now see which list type was clicked:
switch(listType){
case(TYPE_ID_A):
//to action for list A
break;
case(TYPE_ID_B):
//to action for list B
break;
}
}
This works for me but I dont think its great. If any one has another proper design pattern please let us know!
I am using an AutoCompleteTextView to show a list of items the user can select. When the users selects an item, this selected item fills a ListView just below the AutoCompleteTextView. So far so good.
The issue: after the selection of the item out of the AutoCompleteTextView, the AutoCompleteTextView body itself (this "text-box") gets filled up with some text, which is the SimpleCursorAdapter resource (the actual text showing up is: android.widget.SimpleCursorAdapter#4107d010).
What I wish to have: I want the AutoCompleteTextView to refresh and show no text in its own body so the user can immediately type in more text and select further items out of the drop-down list.
Could you please give me a hint how I could achieve that?
Added information:
Thank you Kyle. What I did was to extend SimpleCursorAdapter to SimpleCursorAdapterNoText. I then overridden convertToString() just like you said. I didn't change BindView because I read the documentation twice but I still don't understand what I should change in BindView. Any way - This didn't save the problem - I still get the same string in the AutoComplete. Here is my code:
#SuppressWarnings("deprecation")
private void populateListView()
{
// Get all of the notes from the database and create the item list
Cursor tournamentXCursor = mDbHelper.retrieveTrounamentX(mRowId);
startManagingCursor(tournamentXCursor);
// Create an array to specify the fields we want to display in the list (only name)
String[] from = new String[] {StournamentConstants.TblX.TBL_COLUMN_X_NAME};
// and an array of the fields we want to bind those fields to (in this case just name)
int[] to = new int[]{R.id.competitor_row};
// Now create an array adapter and set it to display using our row
SimpleCursorAdapterNoText tournamentX = new SimpleCursorAdapterNoText(this, R.layout.competitor_row, tournamentXCursor, from, to);
tournamentX.convertToString(tournamentXCursor);
setListAdapter(tournamentX);
}
Anyone has a clue what I am doing wrong?
EDITED:
This is my inherited SimpleCursorAdapter class
public class SimpleCursorAdapterNoText extends SimpleCursorAdapter
{
public SimpleCursorAdapterNoText(Context context, int layout, Cursor c,
String[] from, int[] to)
{
super(context, layout, c, from, to);
// TODO Auto-generated constructor stub
}
#Override
public CharSequence convertToString(Cursor cursor)
{
//Empty string so AutoComplete shows no text
return "";
}
#Override
public void bindView(View view, Context context, Cursor cursor) {
// TODO Auto-generated method stub
super.bindView(view, context, cursor);
}
}
I changed my calling code and eliminated
tournamentX.convertToString(tournamentXCursor);
I was convinced it is essential that I not only override it in my subclass but that I also use it in my calling code so the text inside the AutoComplete will be eliminated.
I am sag to say the this still didn't help - I keep on getting android.database.sqlite.SQLiteCursor#41377578 in the AutoCompleteBox just after I select one item off the AutoComplete selection list.
Thanks D.
If you simply want to clear the text when a user clicks on an item in the dropdown list, define the AutoComplete as a member variable and override it's setOnItemClickListener. Like this:
mAutoComplete.setOnItemClickListener(new OnItemClickListener() {
public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
mAutoComplete.setText("");
}
});
if you are using a simplecursoradapter to fill the textView, you will need to subclass it and override the following method. You will probably also have to override bindview.
#Override
public CharSequence convertToString (Cursor cursor){
return "";
}
You need to put the above inside your SimpleCursorAdapterNoText class, not call it from the top level code.
class extends SimpeCursorAdpaterNotText{
// ... whatever other code you have here
#Override
public CharSequence convertToString (Cursor cursor){
return "";
}
}
How to refresh an Android ListView after adding/deleting dynamic data?
Call notifyDataSetChanged() on your Adapter object once you've modified the data in that adapter.
Some additional specifics on how/when to call notifyDataSetChanged() can be viewed in this Google I/O video.
Also you can use this:
myListView.invalidateViews();
Please ignore all the invalidate(), invalidateViews(), requestLayout(), ... answers to this question.
The right thing to do (and luckily also marked as right answer) is to call notifyDataSetChanged() on your Adapter.
Troubleshooting
If calling notifyDataSetChanged() doesn't work all the layout methods won't help either. Believe me the ListView was properly updated. If you fail to find the difference you need to check where the data in your adapter comes from.
If this is just a collection you're keeping in memory check that you actually deleted from or added the item(s) to the collection before calling the notifyDataSetChanged().
If you're working with a database or service backend you'll have to call the method to retrieve the information again (or manipulate the in memory data) before calling the notifyDataSetChanged().
The thing is this notifyDataSetChanged only works if the dataset has changed. So that is the place to look if you don't find changes coming through. Debug if needed.
ArrayAdapter vs BaseAdapter
I did find that working with an adapter that lets you manage the collection, like a BaseAdapter works better. Some adapters like the ArrayAdapter already manage their own collection making it harder to get to the proper collection for updates. It's really just an needless extra layer of difficulty in most cases.
UI Thread
It is true that this has to be called from the UI thread. Other answers have examples on how to achieve this. However this is only required if you're working on this information from outside the UI thread. That is from a service or a non UI thread. In simple cases you'll be updating your data from a button click or another activity/fragment. So still within the UI thread. No need to always pop that runOnUiTrhead in.
Quick Example Project
Can be found at https://github.com/hanscappelle/so-2250770.git. Just clone and open the project in Android Studio (gradle). This project has a MainAcitivity building a ListView with all random data. This list can be refreshed using the action menu.
The adapter implementation I created for this example ModelObject exposes the data collection
public class MyListAdapter extends BaseAdapter {
/**
* this is our own collection of data, can be anything we
* want it to be as long as we get the abstract methods
* implemented using this data and work on this data
* (see getter) you should be fine
*/
private List<ModelObject> mData;
/**
* our ctor for this adapter, we'll accept all the things
* we need here
*
* #param mData
*/
public MyListAdapter(final Context context, final List<ModelObject> mData) {
this.mData = mData;
this.mContext = context;
}
public List<ModelObject> getData() {
return mData;
}
// implement all abstract methods here
}
Code from the MainActivity
public class MainActivity extends Activity {
private MyListAdapter mAdapter;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
ListView list = (ListView) findViewById(R.id.list);
// create some dummy data here
List<ModelObject> objects = getRandomData();
// and put it into an adapter for the list
mAdapter = new MyListAdapter(this, objects);
list.setAdapter(mAdapter);
// mAdapter is available in the helper methods below and the
// data will be updated based on action menu interactions
// you could also keep the reference to the android ListView
// object instead and use the {#link ListView#getAdapter()}
// method instead. However you would have to cast that adapter
// to your own instance every time
}
/**
* helper to show what happens when all data is new
*/
private void reloadAllData(){
// get new modified random data
List<ModelObject> objects = getRandomData();
// update data in our adapter
mAdapter.getData().clear();
mAdapter.getData().addAll(objects);
// fire the event
mAdapter.notifyDataSetChanged();
}
/**
* helper to show how only changing properties of data
* elements also works
*/
private void scrambleChecked(){
Random random = new Random();
// update data in our adapter, iterate all objects and
// resetting the checked option
for( ModelObject mo : mAdapter.getData()) {
mo.setChecked(random.nextBoolean());
}
// fire the event
mAdapter.notifyDataSetChanged();
}
}
More Information
Another nice post about the power of listViews is found here: http://www.vogella.com/articles/AndroidListView/article.html
Call runnable whenever you want:
runOnUiThread(run);
OnCreate(), you set your runnable thread:
run = new Runnable() {
public void run() {
//reload content
arraylist.clear();
arraylist.addAll(db.readAll());
adapter.notifyDataSetChanged();
listview.invalidateViews();
listview.refreshDrawableState();
}
};
i got some problems with dynamic refresh of my listview.
Call notifyDataSetChanged() on your Adapter.
Some additional specifics on how/when to call notifyDataSetChanged() can be viewed in this Google I/O video.
notifyDataSetChanged() did not work properly in my case[ I called the notifyDataSetChanged from another class]. Just in the case i edited the ListView in the running Activity (Thread). That video thanks to Christopher gave the final hint.
In my second class i used
Runnable run = new Runnable(){
public void run(){
contactsActivity.update();
}
};
contactsActivity.runOnUiThread(run);
to acces the update() from my Activity. This update includes
myAdapter.notifyDataSetChanged();
to tell the Adapter to refresh the view.
Worked fine as far as I can say.
If you are using SimpleCursorAdapter try calling requery() on the Cursor object.
if you are not still satisfied with ListView Refreshment, you can look at this snippet,this is for loading the listView from DB, Actually what you have to do is simply reload the ListView,after you perform any CRUD Operation
Its not a best way to code, but it will refresh the ListView as you wish..
It works for Me....if u find better solution,please Share...
.......
......
do your CRUD Operations..
......
.....
DBAdapter.open();
DBAdapter.insert_into_SingleList();
// Bring that DB_results and add it to list as its contents....
ls2.setAdapter(new ArrayAdapter(DynTABSample.this,
android.R.layout.simple_list_item_1, DBAdapter.DB_ListView));
DBAdapter.close();
The solutions proposed by people in this post works or not mainly depending on the Android version of your device. For Example to use the AddAll method you have to put android:minSdkVersion="10" in your android device.
To solve this questions for all devices I have created my on own method in my adapter and use inside the add and remove method inherits from ArrayAdapter that update you data without problems.
My Code: Using my own data class RaceResult, you use your own data model.
ResultGpRowAdapter.java
public class ResultGpRowAdapter extends ArrayAdapter<RaceResult> {
Context context;
int resource;
List<RaceResult> data=null;
public ResultGpRowAdapter(Context context, int resource, List<RaceResult> objects) {
super(context, resource, objects);
this.context = context;
this.resource = resource;
this.data = objects;
}
#Override
public View getView(int position, View convertView, ViewGroup parent) {
........
}
//my own method to populate data
public void myAddAll(List<RaceResult> items) {
for (RaceResult item:items){
super.add(item);
}
}
ResultsGp.java
public class ResultsGp extends Activity {
#Override
protected void onCreate(Bundle savedInstanceState) {
...........
...........
ListView list = (ListView)findViewById(R.id.resultsGpList);
ResultGpRowAdapter adapter = new ResultGpRowAdapter(this, R.layout.activity_result_gp_row, new ArrayList<RaceResult>()); //Empty data
list.setAdapter(adapter);
....
....
....
//LOAD a ArrayList<RaceResult> with data
ArrayList<RaceResult> data = new ArrayList<RaceResult>();
data.add(new RaceResult(....));
data.add(new RaceResult(....));
.......
adapter.myAddAll(data); //Your list will be udpdated!!!
For me after changing information in sql database nothing could refresh list view( to be specific expandable list view) so if notifyDataSetChanged() doesn't help, you can try to clear your list first and add it again after that call notifyDataSetChanged(). For example
private List<List<SomeNewArray>> arrayList;
List<SomeNewArray> array1= getArrayList(...);
List<SomeNewArray> array2= getArrayList(...);
arrayList.clear();
arrayList.add(array1);
arrayList.add(array2);
notifyDataSetChanged();
Hope it makes sense for you.
If you want to maintain your scroll position when you refresh, and you can do this:
if (mEventListView.getAdapter() == null) {
EventLogAdapter eventLogAdapter = new EventLogAdapter(mContext, events);
mEventListView.setAdapter(eventLogAdapter);
} else {
((EventLogAdapter)mEventListView.getAdapter()).refill(events);
}
public void refill(List<EventLog> events) {
mEvents.clear();
mEvents.addAll(events);
notifyDataSetChanged();
}
For the detail information, please see Android ListView: Maintain your scroll position when you refresh.
Just use myArrayList.remove(position); inside a listener:
myListView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
#Override public void onItemClick(AdapterView<?> parent, android.view.View view, int position, long id) {
myArrayList.remove(position);
myArrayAdapter.notifyDataSetChanged();
}
});
You need to use a single object of that list whoose data you are inflating on ListView. If reference is change then notifyDataSetChanged() does't work .Whenever You are deleting elements from list view also delete them from the list you are using whether it is a ArrayList<> or Something else then Call
notifyDataSetChanged() on object of Your adapter class.
So here see how i managed it in my adapter see below
public class CountryCodeListAdapter extends BaseAdapter implements OnItemClickListener{
private Context context;
private ArrayList<CountryDataObject> dObj;
private ViewHolder holder;
private Typeface itemFont;
private int selectedPosition=-1;
private ArrayList<CountryDataObject> completeList;
public CountryCodeListAdapter(Context context, ArrayList<CountryDataObject> dObj) {
this.context = context;
this.dObj=dObj;
completeList=new ArrayList<CountryDataObject>();
completeList.addAll(dObj);
itemFont=Typeface.createFromAsset(context.getAssets(), "CaviarDreams.ttf");
}
#Override
public int getCount() {
return dObj.size();
}
#Override
public Object getItem(int position) {
return dObj.get(position);
}
#Override
public long getItemId(int position) {
return position;
}
#Override
public View getView(int position, View view, ViewGroup parent) {
if(view==null){
holder = new ViewHolder();
LayoutInflater inflater = (LayoutInflater) context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
view = inflater.inflate(R.layout.states_inflator_layout, null);
holder.textView = ((TextView)view.findViewById(R.id.stateNameInflator));
holder.checkImg=(ImageView)view.findViewById(R.id.checkBoxState);
view.setTag(holder);
}else{
holder = (ViewHolder) view.getTag();
}
holder.textView.setText(dObj.get(position).getCountryName());
holder.textView.setTypeface(itemFont);
if(position==selectedPosition)
{
holder.checkImg.setImageResource(R.drawable.check);
}
else
{
holder.checkImg.setImageResource(R.drawable.uncheck);
}
return view;
}
private class ViewHolder{
private TextView textView;
private ImageView checkImg;
}
public void getFilter(String name) {
dObj.clear();
if(!name.equals("")){
for (CountryDataObject item : completeList) {
if(item.getCountryName().toLowerCase().startsWith(name.toLowerCase(),0)){
dObj.add(item);
}
}
}
else {
dObj.addAll(completeList);
}
selectedPosition=-1;
notifyDataSetChanged();
notifyDataSetInvalidated();
}
#Override
public void onItemClick(AdapterView<?> parent, View view, int position,
long id) {
Registration reg=(Registration)context;
selectedPosition=position;
reg.setSelectedCountryCode("+"+dObj.get(position).getCountryCode());
notifyDataSetChanged();
}
}
Consider you have passed a list to your adapter.
Use:
list.getAdapter().notifyDataSetChanged()
to update your list.
After deleting data from list view, you have to call refreshDrawableState().
Here is the example:
final DatabaseHelper db = new DatabaseHelper (ActivityName.this);
db.open();
db.deleteContact(arg3);
mListView.refreshDrawableState();
db.close();
and deleteContact method in DatabaseHelper class will be somewhat looks like
public boolean deleteContact(long rowId) {
return db.delete(TABLE_NAME, BaseColumns._ID + "=" + rowId, null) > 0;
}
I was not able to get notifyDataSetChanged() to work on updating my SimpleAdapter, so instead I tried first removing all views that were attached to the parent layout using removeAllViews(), then adding the ListView, and that worked, allowing me to update the UI:
LinearLayout results = (LinearLayout)findViewById(R.id.results);
ListView lv = new ListView(this);
ArrayList<HashMap<String,String>> list = new ArrayList<HashMap<String,String>>();
SimpleAdapter adapter = new SimpleAdapter( this, list, R.layout.directory_row,
new String[] { "name", "dept" }, new int[] { R.id.name, R.id.dept } );
for (...) {
HashMap<String, String> map = new HashMap<String, String>();
map.put("name", name);
map.put("dept", dept);
list.add(map);
}
lv.setAdapter(adapter);
results.removeAllViews();
results.addView(lv);
while using SimpleCursorAdapter can call changeCursor(newCursor) on the adapter.
I was the same when, in a fragment, I wanted to populate a ListView (in a single TextView) with the mac address of BLE devices scanned over some time.
What I did was this:
public class Fragment01 extends android.support.v4.app.Fragment implements ...
{
private ListView listView;
private ArrayAdapter<String> arrayAdapter_string;
...
#Override
public void onActivityCreated(Bundle savedInstanceState)
{
...
this.listView= (ListView) super.getActivity().findViewById(R.id.fragment01_listView);
...
this.arrayAdapter_string= new ArrayAdapter<String>(super.getActivity(), R.layout.dispositivo_ble_item, R.id.fragment01_item_textView_titulo);
this.listView.setAdapter(this.arrayAdapter_string);
}
#Override
public void onLeScan(BluetoothDevice device, int rssi, byte[] scanRecord)
{
...
super.getActivity().runOnUiThread(new RefreshListView(device));
}
private class RefreshListView implements Runnable
{
private BluetoothDevice bluetoothDevice;
public RefreshListView(BluetoothDevice bluetoothDevice)
{
this.bluetoothDevice= bluetoothDevice;
}
#Override
public void run()
{
Fragment01.this.arrayAdapter_string.add(new String(bluetoothDevice.toString()));
Fragment01.this.arrayAdapter_string.notifyDataSetChanged();
}
}
Then the ListView began to dynamically populate with the mac address of the devices found.
I think it depends on what you mean by refresh. Do you mean that the GUI display should be refreshed, or do you mean that the child views should be refreshed such that you can programatically call getChildAt(int) and get the view corresponding to what is in the Adapter.
If you want the GUI display refreshed, then call notifyDataSetChanged() on the adapter. The GUI will be refreshed when next redrawn.
If you want to be able to call getChildAt(int) and get a view that reflects what is what is in the adapter, then call to layoutChildren(). This will cause the child view to be reconstructed from the adapter data.
I had an ArrayList which I wanted to display in a listview. ArrayList contained elements from mysql.
I overrided onRefresh method and in that method I used tablelayout.removeAllViews(); and then repeated the process for getting data again from the database.
But before that make sure to clear your ArrayList or whatever data structre or else new data will get appended to the old one..
If you want to update the UI listview from a service, then make the adapter static in your Main activity and do this:
#Override
public void onDestroy() {
if (MainActivity.isInFront == true) {
if (MainActivity.adapter != null) {
MainActivity.adapter.notifyDataSetChanged();
}
MainActivity.listView.setAdapter(MainActivity.adapter);
}
}
If you are going by android guide lines and you are using the ContentProviders to get data from Database and you are displaying it in the ListView using the CursorLoader and CursorAdapters ,then you all changes to the related data will automatically be reflected in the ListView.
Your getContext().getContentResolver().notifyChange(uri, null); on the cursor in the ContentProvider will be enough to reflect the changes .No need for the extra work around.
But when you are not using these all then you need to tell the adapter when the dataset is changing. Also you need to re-populate / reload your dataset (say list) and then you need to call notifyDataSetChanged() on the adapter.
notifyDataSetChanged()wont work if there is no the changes in the datset.
Here is the comment above the method in docs-
/**
* Notifies the attached observers that the underlying data has been changed
* and any View reflecting the data set should refresh itself.
*/
I was only able to get notifyDataSetChanged only by getting new adapter data, then resetting the adapter for the list view, then making the call like so:
expandableAdapter = baseFragmentParent.setupEXLVAdapter();
baseFragmentParent.setAdapter(expandableAdapter);
expandableAdapter.notifyDataSetChanged();
on other option is onWindowFocusChanged method, but sure its sensitive and needs some extra coding for whom is interested
override fun onWindowFocusChanged(hasFocus: Boolean) {
super.onWindowFocusChanged(hasFocus)
// some controls needed
programList = usersDBHelper.readProgram(model.title!!)
notesAdapter = DailyAdapter(this, programList)
notesAdapter.notifyDataSetChanged()
listview_act_daily.adapter = notesAdapter
}
If I talked about my scenario here, non of above answers will not worked because I had activity that show list of db values along with a delete button and when a delete button is pressed, I wanted to delete that item from the list.
The cool thing was, I did not used recycler view but a simple list view and that list view initialized in the adapter class. So, calling the notifyDataSetChanged() will not do anything inside the adapter class and even in the activity class where adapter object is initialized because delete method was in the adapter class.
So, the solution was to remove the object from the adapter in the adapter class getView method(to only delete that specific object but if you want to delete all, call clear()).
To you to get some idea, what was my code look like,
public class WordAdapter extends ArrayAdapter<Word> {
Context context;
public WordAdapter(Activity context, ArrayList<Word> words) {}
//.......
#NonNull
#Override
public View getView(final int position, View convertView, ViewGroup group) {
//.......
ImageButton deleteBt = listItemView.findViewById(R.id.word_delete_bt);
deleteBt.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
if (vocabDb.deleteWord(currentWord.id)) {
//.....
} else{
//.....
}
remove(getItem(position)); // <---- here is the trick ---<
//clear() // if you want to clear everything
}
});
//....
Note: here remove() and getItem() methods are inherit from the Adapter class.
remove() - to remove the specific item that is clicked
getItem(position) - is to get the item(here, thats my Word object
that I have added to the list) from the clicked position.
This is how I set the adapter to the listview in the activity class,
ArrayList<Word> wordList = new ArrayList();
WordAdapter adapter = new WordAdapter(this, wordList);
ListView list_view = (ListView) findViewById(R.id.activity_view_words);
list_view.setAdapter(adapter);
After adding/deleting dynamic data in your "dataArray" do:
if you use an ArrayAdapter
adapter.notifyDataSetChanged();
if you use a customAdapter that extends ArrayAdapter
adapter.clear();
adapter.addAll(dataArray);
adapter.notifyDataSetChanged();
if you use a customAdapter that extends BaseAdapter
adapter.clear();
adapter.getData().addAll(dataArray);
adapter.getData().notifyDataSetChanged();
The easiest is to just make a new Adaper and drop the old one:
myListView.setAdapter(new MyListAdapter(...));
I am using the following code to set the adapter (SimpleCursorAdapter) for an AutoCompleteTextView
mComment = (AutoCompleteTextView) findViewById(R.id.comment);
Cursor cComments = myAdapter.getDistinctComments();
scaComments = new SimpleCursorAdapter(this,R.layout.auto_complete_item,cComments,new String[] {DBAdapter.KEY_LOG_COMMENT},new int[]{R.id.text1});
mComment.setAdapter(scaComments);
auto_complete_item.xml
<?xml version="1.0" encoding="utf-8"?>
<TextView
xmlns:android="http://schemas.android.com/apk/res/android"
android:id="#+id/text1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"/>
and thi is the xml for the actual control
<AutoCompleteTextView
android:id="#+id/comment"
android:hint="#string/COMMENT"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:textSize="18dp"/>
The dropdown appears to work correctly, and shows a list of items. When I make a selection from the list I get a sqlite object ('android.database.sqlite.SQLiteCursor#'... ) in the textview.
Anyone know what would cause this, or how to resolve this?
thanks
Ok I am able to hook into the OnItemClick event, but the TextView.setText() portion of the AutoCompleteTextView widget is updated after this point. The OnItemSelected() event never gets fired, and the onNothingSelected() event gets fired when the dropdown items are first displayed.
mComment.setOnItemClickListener( new OnItemClickListener() {
#Override
public void onItemClick(AdapterView<?> arg0, View arg1, int arg2,
long arg3) {
// TODO Auto-generated method stub
SimpleCursorAdapter sca = (SimpleCursorAdapter) arg0.getAdapter();
String str = getSpinnerSelectedValue(sca,arg2,"comment");
TextView txt = (TextView) arg1;
txt.setText(str);
Toast.makeText(ctx, "onItemClick", Toast.LENGTH_SHORT).show();
}
});
mComment.setOnItemSelectedListener(new OnItemSelectedListener() {
#Override
public void onItemSelected(AdapterView<?> arg0, View arg1,
int arg2, long arg3) {
Toast.makeText(ctx, "onItemSelected", Toast.LENGTH_SHORT).show();
}
#Override
public void onNothingSelected(AdapterView<?> arg0) {
// TODO Auto-generated method stub
Toast.makeText(ctx, "onNothingSelected", Toast.LENGTH_SHORT).show();
}
});
Anyone alse have any ideas on how to override the updating of the TextView?
thanks
patrick
I don't think you should have to update the text for the AutoCompleteTextView. It should do it automatically. It does this by calling the [CursorAdapter.convertToString(...)][1] method. if you read the description of the method it points this out. So if you were writing your own CursorAdapter you would override that method to return whatever text you would want to show up in the list of suggestions. This guy does a good job of explaining how to do it:
Line 86 - http://thinkandroid.wordpress.com/2010/02/08/writing-your-own-autocompletetextview/
However, since you are using a SimpleCursorAdapter, you can't override this method. Instead you need implement/create a [SimpleCursorAdapter.CursorToStringConverter][2] and pass it into [SimpleCursorAdapter.setCursorToStringConverter(...)][3]:
SimpleCursorAdapter adapter = new SimpleCursorAdapter(context, layout, cursor, from, to);
CursorToStringConverter converter = new CursorToStringConverter() {
#Override
public CharSequence convertToString(Cursor cursor) {
int desiredColumn = 1;
return cursor.getString(desiredColumn);
}
};
adapter.setCursorToStringConverter(converter);
Or if you don't want to create a CursorToStringConverter then use the [SimpleCursorAdapter. setStringConversionColumn(...)][4] method. But I think you still have to explicitly set the CursorToStringConverter to null:
int desiredColumn = 1;
adapter.setCursorToStringConverter(null);
adapter.setStringConversionColumn(desiredColumn);
Sorry, but the spam blocker won't let me post the links to the Android Documentation that describes the links I posted above. But a quick google search will point you to the correct doc pages.
[Late answer, just for the record. EDITed to remove my suggestion that subclassing is necessary.]
To use SimpleCursorAdapter with an AutoCompleteTextView, you need to set two handlers on the adapter: The CursorToStringConverter, and the FilterQueryProvider. Pseudocode follows:
adapter.setCursorToStringConverter(new CursorToStringConverter() {
public String convertToString(android.database.Cursor cursor) {
// Assume that "someColumn" contains the strings that we want to
// use to identify rows in the result set.
final int columnIndex = cursor.getColumnIndexOrThrow("someColumn");
final String str = cursor.getString(columnIndex);
return str;
}
});
adapter.setFilterQueryProvider(new FilterQueryProvider() {
public Cursor runQuery(CharSequence constraint) {
// runSomeQuery will look for all rows in the database
// that match the given constraint.
Cursor cursor = runSomeQuery(constraint);
return cursor;
}
});
When I make a selection from the list
I get a sqlite object
('android.database.sqlite.SQLiteCursor#'...
) in the textview.
You do not say what this "textview" is or how it relates to the Spinner.
I am going to take an educated guess and assume that you are simply assigning the selected item out of the Spinner into the TextView.
The selected item from a Spinner using a SimpleCursorAdapter is a Cursor, pointing at the row the user selected. The toString() implementation of Cursor will give you something akin to android.database.sqlite.SQLiteCursor# depending on where the Cursor came from.
More likely, you are going to want to call getString() on that Cursor, to retrieve some column value, and assign it to the TextView in question.
To solve the problem I just extended SimpleCursorAdapter and implemented the method convertToString(). Then I created an instance and set it as the adapter.
In order to allow filtering in AutoCompleteTextView when using CursorAdapters I also used setFilterQueryProvider(). See this question.
My extended class inside the Activity looks as:
private static class AutoCompleteCursorAdapter extends SimpleCursorAdapter {
public AutoCompleteCursorAdapter(Context context, int layout, Cursor c, String[] from, int[] to) {
super(context, layout, c, from, to);
}
#Override
public CharSequence convertToString(Cursor cursor) {
// This is the method that does the trick (return the String you need)
return cursor.getString(cursor.getColumnIndex("name"));
}
}