Develop Reference

Show only certain items in recycleview according to condition

I have a recycleview showing a list of audio files fetched from my audios.json file hosted on my server. i have a model class with a getter method getLanguage() to see the audio language. I would like to show only audio files of users preference in recycle view. Say for example, if user wants only english and russian i would like to show only list of russian and english. How can we achieve this? Right now the entire list is displayed.
public class AudioAdapter extends RecyclerView.Adapter<AudioAdapter.HomeDataHolder> {
int currentPlayingPosition = -1;
Context context;
ItemClickListener itemClickListener;
List<Output> wikiList;
public AudioAdapter(List<Output> wikiList, Context context) {
this.wikiList = wikiList;
this.context = context;
}
#NonNull
#Override
public HomeDataHolder onCreateViewHolder(#NonNull ViewGroup viewGroup, int i) {
View view = LayoutInflater.from(context).inflate(R.layout.audio_row_layout,viewGroup,false);
HomeDataHolder mh = new HomeDataHolder(view);
return mh;
}
#Override
public void onBindViewHolder(#NonNull final HomeDataHolder homeDataHolder, int i) {
String desc = wikiList.get(i).getLanguage() + " • " + wikiList.get(i).getType();
homeDataHolder.tvTitle.setText(wikiList.get(i).getTitle());
homeDataHolder.tvotherinfo.setText(desc);
homeDataHolder.itemView.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
if (itemClickListener != null)
itemClickListener.onClick(view,homeDataHolder.getAdapterPosition());
}
});
homeDataHolder.rippleLayout.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
if (itemClickListener != null)
itemClickListener.onClick(view,homeDataHolder.getAdapterPosition());
}
});
}
#Override
public int getItemCount() {
return wikiList.size();
}
#Override
public long getItemId(int position) {
return position;
}
#Override
public int getItemViewType(int position) {
return position;
}
public void setClickListener(ItemClickListener itemClickListener) { // Method for setting clicklistner interface
this.itemClickListener = itemClickListener;
}
public class HomeDataHolder extends RecyclerView.ViewHolder {
TextView tvTitle,tvotherinfo;
MaterialRippleLayout rippleLayout;
public HomeDataHolder(View v) {
super(v);
this.tvTitle = v.findViewById(R.id.title);
this.tvotherinfo = v.findViewById(R.id.audioDesc);
this.rippleLayout = v.findViewById(R.id.ripple);
}
}
}

The general idea for this should be:
you have one list with all items
you have filter rules selected by the user
You filter items from number 1, to see which ones match the constraints and store this in another list.
Then the recycler view only shows the items of the list from number 3.
This means that recycler view's getItemCount would return the size of the filtered list, not the whole list.

Instead of passing the wikiList as it is, filter it then send it:
Lets say that you filled up the wikiList, before passing it to the adapter, filter it like this:
In the activity that you initialize the adapter in:
public class YourActivity extends ............{
........
........
//your filled list
private List<Output> wikiList;
//filtered list
private List<Output> filteredList= new ArrayList<Output>();
//filters
private List<String> filters = new ArrayList<String>();
//lets say the user chooses the languages "english" and "russian" after a button click or anything (you can add as many as you want)
filters.add("english");
filters.add("russian");
//now filter the original list
for(int i = 0 ; i<wikiList.size() ; i++){
Output item = wikiList.get(i);
if(filters.contains(item.getLanguage())){
filteredList.add(item);
}
}
//now create your adapter and pass the filteredList instead of the wikiList
AudioAdapter adapter = new AudioAdapter(filteredList , this);
//set the adapter to your recyclerview........
......
.....
......
}
I use above "english" and "russian" for language. I don't know how they are set in your response, maybe you use "en" for "english" so be careful.

custom adapter isn't showing any items

This is a follow on from an earlier question: ImageButton within row of ListView android not working
But after suggestions from SO gurus it has been suggested I post a new question.
The issue is that I have a custom adapter that is not showing any data. I have looked into other questions, but it didn't provide a solution.
In my Main Activity I have a couple of buttons, one of them: ToDo, should create a row that displays data from a SQLite database, and depending on some factors (dates mainly), it shows a type of traffic light that is stored as a drawable.
Part of the Items in this Row is an Image Button that I want the user to be able to click and the image should change. The user should be able also to click on the actual row and a new activity starts.
The issue I have is that NO DATA is being displayed.
So, here is my code:
public class MainActivity extends Activity {
// definitions etc ...
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
// definitions etc ...
}
public void ToDo(View v){ // the user has clicked in the ToDo button
IgroDatabaseHelper helper = new IgroDatabaseHelper(getBaseContext()); // create instance of SQLIte database
numRows = helper.NumEntries("ToDo"); // Get the number of rows in table
int i = 1;
ArrayList<RowItem> rowItems = new ArrayList<>();
RowItem myItem1;
while (i <= numRows){
// get items from database
// depending on value select different drawable
// put data into List Array of RowItem
myItem1 = new RowItem(TheWhat, R.drawable.teamworka, R.drawable.redtrafficlight, R.drawable.checkbox, TheWhenBy);
rowItems.add(myItem1);
//
i = i+ 1;
}
ListView yourListView = (ListView) findViewById(R.id.list);
CustomListViewAdapter customAdapter = new CustomListViewAdapter(this, R.layout.todo_row, rowItems);
yourListView.setAdapter(customAdapter);
}
The CustomListViewAdapter looks like this:
public class CustomListViewAdapter extends ArrayAdapter<RowItem> {
Context context;
ArrayList<RowItem> _rowItems;
public CustomListViewAdapter(Context context, int resourceId,
ArrayList<RowItem> rowItems) {
super(context, resourceId);
this.context = context;
_rowItems = rowItems;
System.out.println("I am in the custom Adapter class "+ _rowItems);
}
#Override
public View getView(int position, View convertView, ViewGroup parent){
System.out.println("This is the get view");
View row = convertView;
RowItem item = _rowItems.get(position);
// you can now get your string and drawable from the item
// which you can use however you want in your list
String columnName = item.getColumnName();
int drawable = item.getDrawable();
if (row == null) {
LayoutInflater mInflater = (LayoutInflater) context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
row = mInflater.inflate(R.layout.todo_row, parent, false);
}
ImageButton chkDone = (ImageButton) row.findViewById(R.id.chkDone);
chkDone.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
View parentRow = (View) v.getParent();
ListView listView = (ListView) parentRow.getParent();
final int position = listView.getPositionForView(parentRow);
System.out.println("I am in position "+ position);
}
});
return row;
}
}
The RowItem Class looks like:
public class RowItem {
private String _heading;
private int _icon;
private int _lights;
private int _chkdone;
private String _date;
public RowItem(String heading, int icon, int lights, int chkDone, String date) {
_heading = heading;
_icon = icon;
_lights = lights;
_chkdone = chkDone;
_date = date;
System.out.println("adding stuff to my rows");
System.out.println("my column Name is " + heading);
System.out.println("My drawable int is "+ icon);
}
public String getColumnName() {
System.out.println("column Names is "+ _heading);
return _heading;
}
public int getDrawable() {
return _icon;
}
public int getLights(){
return _lights;
}
public int getchkDone(){
return _chkdone;
}
public String getDate(){
return _date;
}
}
I am obviously missing something, as I mentioned earlier, no data gets shown. I know that there are 2 row items that get passed to the CustomListViewAdapter. But I also know that the View getView inside the CustomListViewAdapter does not actually get called.
I hope I have put enough information/code, but if you feel I need to explain something further, please say.
Thanking all very much in advance!

I don't see a getCount() method. You should be overriding it like this:
#Override
public int getCount() {
return _rowItems.getCount();
}
Alternatively, calling super(context, resourceId, rowItems); should also fix it.

Your ListView thinks there are no items to display. If you are using your own array, you must override the getCount() method to indicate the number of items you want to display.

How to detect change in listview from mainactivity

Summary: I need a way to trigger my calculate() function within my main activity when an item is added or removed from my ListView
Background:
My android application fills a listview with list items. A list item contains a textview and an imagebutton (delete) that removes the item from the list on click. I use a custom adapter to keep track of changes in the list. This all works fine.
In my main acticity, some calculations take place based on the values in the list in a function called calulate(). I want to call this function whenever an item is added or deleted from the list. However, I don't know if this is possible and how to implement such a function.
I noticed that it is possible to add an observer using registerDataSetObserver() that will be notified when notifyDataSetChanged() is called. However, I'm not sure if this is what I need and how to implement this. Any help or suggestions are more than welcome.
Here is my CustomListAdapter:
public class CustomListAdapter extends BaseAdapter {
static final String TAG = "CustomListAdapter";
private Context context;
ArrayList <String> listArray;
LayoutInflater inflater;
public CustomListAdapter(Context context, List <String> inputArray) {
super();
this.context = context;
this.listArray = (ArrayList<String>) inputArray;
}
#Override
public int getCount() {
return listArray.size(); // total number of elements in the list
}
#Override
public String getItem(int i) {
return listArray.get(i); // single item in the list
}
#Override
public long getItemId(int i) {
return i; // index number
}
#Override
public View getView(int position, View convertView, final ViewGroup parent) {
View V = convertView;
if(V == null) {
LayoutInflater vi = (LayoutInflater) context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
V = vi.inflate(R.layout.selected_drug_list_item, null);
}
//place text in textview
String listItem = listArray.get(position);
TextView textView = (TextView) V.findViewById(R.id.selectedDrugName);
textView.setText(listItem);
ImageButton deleteSelectedDrugButton = (ImageButton) V.findViewById(R.id.deleteSelectedDrugButton);
deleteSelectedDrugButton.setTag(position);
//Listener for the delete button. Deletes item from list.
deleteSelectedDrugButton.setOnClickListener(new OnClickListener() {
#Override
public void onClick(View view) {
//re
Integer index = (Integer) view.getTag();
listArray.remove(index.intValue());
notifyDataSetChanged();
}
});
return V;
}
public void add(String input) {
listArray.add(input);
notifyDataSetChanged();
Log.v(TAG, input + " added to list");
}
public void remove(String input){
listArray.remove(input);
notifyDataSetChanged();
Log.v(TAG, input + " added to list");
}
}
Here is how my ListView is initialized in my onCreate() method.
selectionListView = (ListView) findViewById(R.id.selectionListView);
selectionAdapter = new CustomListAdapter(this,myListItems);
selectionListView.setAdapter(selectionAdapter);
If any other code fragment is required, I'll happily provide it.

You may create Interfece that will be implemented by Your Main Activity and passed to Adapter (eg. in constructor)
public interface SomeInterface
{
public void foo();
}
Add SomeInterface object in Your Adapter
SomeInterface responder=null;
public CustomListAdapter(Context context, List <String> inputArray, SomeInterface responder) {
super();
this.context = context;
this.listArray = (ArrayList<String>) inputArray;
this.responder=responder;
}
public void add(String input) {
listArray.add(input);
notifyDataSetChanged();
Log.v(TAG, input + " added to list");
responder.foo();
}
public void remove(String input){
listArray.remove(input);
notifyDataSetChanged();
Log.v(TAG, input + " added to list");
responder.foo();
}
and implements SomeInterface in Your MainActivity
public class MainActivity extends Activity implements SomeInterface
{
...
public void foo()
{
//do whatever
}
private initializeAdapter()
{
CustomListAdapter adapter=new Adapter(this, someArray, this);
}
}

You can create a callback interface with a simple method, like stuffHappened(). Then, let your activity implement that interface. Now you can add a constructor argument which has as type the callback interface, pass the activity in, keep it as a member variable on the adapter and call the stuffHappened() method whenever you need to send feedback to your activity.

How to delete a custom listview item in android?

I have a listview and a button in my layout file. I'am adding items to listview on click of that button. The listview should be empty when the activity is started but it should grow by adding the items to it.
This is my code inside onCreate() :
list = (ListView)findViewById(R.id.inverterListView);
adapter = new ArrayAdapter<String>(InverterList.this, R.layout.inverters_list_row, R.id.inverterNumberTextViewInPanelListRow);
list.setAdapter(adapter);
And here iam adding the items to listview onclick of a button.
adapter.add(inverterNo);
adapter.notifyDataSetChanged();
This works fine. Can anyone guide me to delete custom listview item ? Thanks in advance.

If you know the position of the item you can do this:
Object item = adapter.getItem(position);
adapter.remove(item);
adapter.notifyDataSetChanged();

You may write your own adapter extends BaseAdapter and implement all you need methods.
It is example of my adapter:
public class PeopleUserAdapter extends BaseAdapter
{
private List<User> users;
private int viewResourceId;
private Context context;
public PeopleUserAdapter(Context context, int viewResourceId)
{
this.context = context;
this.viewResourceId = viewResourceId;
this.users = new ArrayList<User>();
}
#Override
public View getView(int position, View convertView, ViewGroup parent)
{
UserItemHolder holder;
if (convertView == null)
{
convertView = LayoutInflater.from(context).inflate(viewResourceId, parent, false);
holder = new UserItemHolder(convertView);
}
else holder = (UserItemHolder) convertView.getTag();
User user = getItem(position);
holder.name.setText("#" + user.getLogin());
return convertView;
}
#Override
public int getCount()
{
return users.size();
}
#Override
public User getItem(int position)
{
return users.get(position);
}
#Override
public long getItemId(int position)
{
return getItem(position).hashCode();
}
public void clear()
{
users.clear();
}
public void addAll(Collection<User> users)
{
this.users.addAll(users);
notifyDataSetChanged();
}
public void replace(Collection<User> users)
{
clear();
addAll(users);
}
public static PeopleUserAdapter init(Context context)
{
return new PeopleUserAdapter(context, R.layout.item_user);
}
}

adapter.remove(item) .. and then call adapter.notifyDataSetChanged();

In case you are using a custom adapter (for a custom layout listview), you will want to do this:
When your Adapter is something like:
public class YourAdapterName extends ArrayAdapter<yourObject>
then the code for deleting the selected ListView Item will be:
ListView yourListView = (ListView) findViewById(R.id.listviewid);
YourAdapterName adapter;
adapter = (YourAdapterName) yourListView.getAdapter();
yourObject theitem = adapter.getItem(position);
adapter.remove(theitem);
adapte.notifyDataSetChanged();
This is assuming you are inside an event that gives you access to the current position inside the listview. like:
public boolean onItemLongClick(AdapterView<?> parent, View strings,int position, long id)
or
public void onItemClick(AdapterView<?> arg0, View v, int position, long id)
Otherwise you will need to obtain that position some other way, like storing it (onItemClick or onItemLongClick) in a textView with Visibility.GONE, and retrieve it when clicking the button (this is silly, you can use all kinds of storage options, like global variables, database and such).

Make sure you have overridden the remove method on your custom adapter
For example if this is your add method:
#Override
public void add(String[] object) {
scoreList.add(object);
super.add(object);
}
then your remove method would look something like this:
#Override
public void remove(String[] object) {
scoreList.remove(object);
super.remove(object);
}

call the below two lines::
adapter.remove(inverterNo);
adapter.notifyDataSetChanged();
where inverterNo is your item

It easy; you only to need is: add a method public in your personalize adapter some this:
public void remove(int position) {
itemsMovieModelFiltered.remove(position);
notifyDataSetChanged();
}
Remenber, this method you must add in your personalize adapter.
Then, call this method from other
adapte=new PersonalizeListAdapter(getActivity().getApplicationContext(),
movieModelList);
adapte.remove(position);

Customizing onClickItem listner - ListActivity

I am creating a contact list view, diplaying user name,user email and user id. Now while clicking on particular item i want to post some event to server based on the user id. How to get the user id inside the onClickItem listener, as user id is long value. i am able to get the user name that means the text but not the user id.

listView has onCLicklistener that has parameter position.If you are using arrayList to inflate ListView then you can use this positon to get corresponding object.

You can try to set the user id to tag using View.setTag and View.getTag. There are two version available choose the one you need. This way you can attach the user id as tag and then get it back.
http://developer.android.com/reference/android/view/View.html#setTag(int, java.lang.Object)
You code should look like:
view.setTag(Long.valueOf(id));
.....
onClickListener(..) {
Long id = (Long)view.getTag();
}

You should make your own bean class which contains your userid and put it in List (or ArrayList)
then create an adapter by creating a class extending ArrayAdapter (for instance) to bind your list of this bean class
register a listener either using onItemClickListener or View listener in your row if you inflate your custom layout.
get the position and use it to retrieve your userid on your bean list.
Here's my snippet
public class ListActivity extends Activity implements OnItemClickListener {
private Context context;
private RowAdapter adapter;
private ArrayList<Row> rowList = new ArrayList<Row>();
/** Called when the activity is first created. */
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
context = ListActivity.this;
initRows();
adapter = new RowAdapter(context, rowList);
ListView listView = (ListView) findViewById(R.id.listView);
listView.setAdapter(adapter);
listView.setOnItemClickListener(this);
}
private void initRows() {
Row row = new Row(1);
rowList.add(row);
row = new Row(2);
rowList.add(row);
}
public class Row {
long userid = 0;
public Row(long userid) {
this.userid = userid;
}
public long getUserid() {
return userid;
}
public void setUserid(long userid) {
this.userid = userid;
}
}
public class RowAdapter extends ArrayAdapter<Row> {
private Context context;
public RowAdapter(Context context, ArrayList<Row> bindList) {
super(context, R.layout.row_layout, bindList);
this.context = context;
}
#Override
public View getView(final int position, View convertView, ViewGroup parent) {
View view = convertView;
if(view == null) {
LayoutInflater inflater = (LayoutInflater) context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
view = inflater.inflate(R.layout.row_layout, null);
}
//if you use some additional View you can retrieve your position using this
Button button = view.findViewById(R.id.button);
button.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
updateSelected(position);
}
});
return view;
}
}
//or if you rather just listen on row click then you can retrieve your position using this
#Override
public void onItemClick(AdapterView<?> arg0, View view, int position, long arg3) {
updateSelected(position);
}
private void updateSelected(int position) {
rowList.get(position).getUserid();
//have it your way
}
}