I'm using a RecyclerView to implement a NavigationDrawer.
I got click events working, but I can't figure out how to have the first item selected on App start and following that keep the selected item higlighted even if the drawer is not shown.
All I've been able to find is multi-selection in RecyclerView.
I actually just implemented this in an app I am working on. So this method worked:
First create a variable to track the current selected position at the top of your adapter:
private int selectedItem;
Then in your Adapter constructor initiate the selectedItem value you would like:
public NavDrawerMenuListAdapter(Context context, List<NavDrawerItem> data, NavDrawerMenuListViewHolder.NavDrawerMenuClickInterface listener) {
this.context = context;
mLayoutInflater = LayoutInflater.from(context);
this.navDrawerItems = data;
this.listener = listener;
selectedItem = 0;
}
Here I use 0 as this is the first item in my menu.
Then in your onBindViewHolder(NavDrawerMenuListViewHolder holder, int position) just check whether your selectedItem == position and set the background of some view to a seleted background like so:
if (selectedItem == position) {
holder.single_title_textview.setTextColor(0xff86872b);
holder.nav_drawer_item_holder.setBackgroundColor(Color.DKGRAY);
}
Here I set the text color to green and give the Realativelayout parent a gray background on start. You can, of course, customize this in any way you like.
To implement a selection of an item and keep the state I use the following method:
public void selectTaskListItem(int pos) {
int previousItem = selectedItem;
selectedItem = pos;
notifyItemChanged(previousItem);
notifyItemChanged(pos);
}
This method I usually call from the OnClick() method.
Hope this helps!.
Related
I have created a RecyclerView with alternating row color like this:
Whenever I delete an row from the list say for example I delete row whose product name is cookies my list gets updated like this:
as you can see the updated list no longer supports alternating row color. The simple solution would be to change the background color of next View (row) after deleting the current View. For that I first need a reference of next View but as a beginner in android I don't know how to get it.
Adapter:
public class Adapter extends RecyclerView.Adapter<Adapter.ViewHolder>{
private List<Model> originalList;
Adapter(List<Model> list){ originalList = list; }
#Override
public void onBindViewHolder(final Adapter.ViewHolder holder, final int position) {
Model list = originalList.get(position);
if (position % 2 == 1)
holder.itemView.setBackgroundColor(Color.parseColor("#e9e9e9"));
final View holder.nextItemView = ? // how to get reference to next View here
holder.product.setText(list.getName());
holder.price.setText(String.valueOf(list.getPrice()));
holder.quantity.setText(String.valueOf(list.getQuantity()));
holder.options.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
showPopupMenu(holder.options, nextItemView, position);
}
});
}
private void showPopupMenu(View options, final View view, final int position){
final PopupMenu popup = new PopupMenu(options.getContext(), options);
MenuInflater inflater = popup.getMenuInflater();
inflater.inflate(R.menu.options_menu, popup.getMenu());
popup.setOnMenuItemClickListener(new PopupMenu.OnMenuItemClickListener() {
#Override
public boolean onMenuItemClick(MenuItem item) {
String menuItem = item.toString();
if (menuItem.equals("Delete")){
originalList.remove(position);
notifyItemRemoved(position);
int count = originalList.size();
if (count != 0){
int color = Color.TRANSPARENT;
Drawable background = view.getBackground();
if (background instanceof ColorDrawable)
color = ((ColorDrawable) background).getColor();
if (color == Color.parseColor(#e9e9e9))
color = Color.TRANSPARENT;
view.setBackground(color);
}
}
return true;
}
});
popup.show();
}
}
options is a ImageButton on the click of which I show a popup menu with item labelled as Delete on click of which the row gets deleted from the list.
Quick fix you can call notifyDataSetChanged() instead of notifyItemRemoved(position)
and add an else part
if (position % 2 == 1)
holder.itemView.setBackgroundColor(Color.parseColor("#e9e9e9")); // gray
else
holder.itemView.setBackgroundColor(Color.parseColor("#ffffff")); // white
but this solution will do heavy operations if your list contains a lot of items
the solution which I recommend is using ListAdapter with DiffUtil which will trigger the operation for the only modified items , you can find a sample for it here link1 ,link2, link3
when an item removed. background of all items after that need to be updated.
Method 1
so after you remove item with position of p from list of itemList and notify it you have to do this.
if (itemList.size - p > 0)
notifyItemRangeChanged(p, itemList.size - p)
Method 2
at this point it should work but it can be more optimized. you need just change background but now it will call onBindViewHolder for each items after p.
you can use payload to just change background and do nothing more.
add a const value:
const val PAYLOAD_BACKGROUND = 10
change first method code into this. it says that only update background.
if (itemList.size - p > 0)
notifyItemRangeChanged(p, itemList.size - p, PAYLOAD_BACKGROUND)
override this method
onBindViewHolder(holder, position, payloads)
after you implemented this method the previous onBindViewHolder method will not call anymore. and you have to do all of that inside this method.
onBindViewHolder(holder, position, payloads) {
if (payloads.contains(PAYLOAD_BACKGROUND) || payloads.isEmpty()) {
// set background color
}
if (payloads.isEmpty()) {
// do anything else that you were doing inside onBindViewHolder
}
}
if payloads is not empty it means this is a partial update. but if payloads is empty means this is a complete update like the old onBindViewHolder
I am actually making some visibility changes to items that are clicked of the recycler view. But when the user clicks on one object and then clicks on the other object then the previous object should come to its initial state.
The manager.findViewByPosition(position) is working fine if the view is in focus of the screen but I am not able to get the view if the element is not in current focus.
For example:- the user clicks on 1st(position) item then clicks on the last position then the findViewByPosition returns a null.
Please help and let me know if there is some other way of doing it.
The expected result should be the view of the last item to be refreshed but it's not happening for the views that are not in the current focus of the screen.
Below is my code snippet. Updated with what you suggested.
public class BodyPartWithMmtRecyclerView extends
RecyclerView.Adapter<BodyPartWithMmtRecyclerView.ViewHolder>
{
//variables defined.
int selectedPosition = -1;
static class ViewHolder extends RecyclerView.ViewHolder {
//All the view items declared here.
ViewHolder(View view) {
super(view);
//All the views are defined here.
}
}
public BodyPartWithMmtRecyclerView(List<BodyPartWithMmtSelectionModel> bodyPartsList, Context context){
//array list initialization and shared preference variables initialization
}
public BodyPartWithMmtRecyclerView.ViewHolder onCreateViewHolder(#NonNull ViewGroup parent, int viewType) {
//Creating a new view.
}
public void onBindViewHolder(#NonNull final BodyPartWithMmtRecyclerView.ViewHolder holder, #SuppressLint("RecyclerView") final int position) {
BodyPartWithMmtSelectionModel bodyPartWithMmtSelectionModel = bodyPartsList.get(position);
holder.iv_bodypart.setImageResource(bodyPartWithMmtSelectionModel.getIv_body_part());
holder.tv_body_part_name.setText(bodyPartWithMmtSelectionModel.getExercise_name());
if(selectedPosition!=position && selectedPosition!=-1){
//updated the elements view to default view. Like made the visibility and other changes here.
}
//some click listeners on the sub-elements of the items. Like textviews, spinner, etc
holder.iv_bodypart.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
((BodyPartSelection)context).setFabVisible();
if(selectedPosition!=-1){
((BodyPartSelection)context).visibilityChanged(selectedPosition,position);
/*here what I was doing is whenever the user clicks on an item I check weather a previous item is clicked or not then if yes then I send the position to a function that makes it to default but the issue was that if the item is not in the focus of the screen the findViewByPosition returns null.*/
}
selectedPosition = position;
bodypartSelected = holder.tv_body_part_name.getText().toString();
holder.iv_bodypart.setVisibility(View.INVISIBLE);
holder.rl_left_right.setVisibility(View.VISIBLE);
}
});
//and other listeners below
}
#Override
public int getItemCount() {
return bodyPartsList==null?0:bodyPartsList.size();
}
#Override
public int getItemViewType(int position) {
return position;
}
}
VisibilityChanged function
public void visibilityChanged(int position, int clicked){
View view = manager.findViewByPosition(position);
if(view!=null) {
Log.i("inside","visibility change");
ImageView imageView = view.findViewById(R.id.bodypartImage);
//other elements and changing the visibility of elemets to default.
}
}
I have updated my code based on the snippet you updated. Please don't change the visibility condition if-else I have added with any different logic which I saw in your code snippet. As you did, it will not update both selected and default view as RecyclerView reuse the view layout. So if the condition is not proper, you may see multiple items as selected or some other types of unwated behaviour.
public void onBindViewHolder(#NonNull final BodyPartWithMmtRecyclerView.ViewHolder holder, #SuppressLint("RecyclerView") final int position) {
BodyPartWithMmtSelectionModel bodyPartWithMmtSelectionModel = bodyPartsList.get(position);
holder.iv_bodypart.setImageResource(bodyPartWithMmtSelectionModel.getIv_body_part());
holder.tv_body_part_name.setText(bodyPartWithMmtSelectionModel.getExercise_name());
if(selectedPosition == position){
//updated the elements view to SELECTED VIEW. Like made the visibility and other changes here.
} else {
//updated the elements view to default view. Like made the visibility and other changes here.
}
//some click listeners on the sub-elements of the items. Like textviews, spinner, etc
holder.iv_bodypart.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
((BodyPartSelection)context).setFabVisible();
/Comment by Hari: Don't try to change the visibility of default as it will be done automatically after calling notifyDataSetChanged(). */
if(selectedPosition!=-1){
((BodyPartSelection)context).visibilityChanged(selectedPosition,position);
/*here what I was doing is whenever the user clicks on an item I check weather a previous item is clicked or not then if yes then I send the position to a function that makes it to default but the issue was that if the item is not in the focus of the screen the findViewByPosition returns null.*/
/*Comment by Hari: This snippet is valuable which is missing as you are getting null issue here.
However Don't try to change the visibility of default as it will be done automatically after calling notifyDataSetChanged(). */
}
selectedPosition = position;
bodypartSelected = holder.tv_body_part_name.getText().toString();
holder.iv_bodypart.setVisibility(View.INVISIBLE);
holder.rl_left_right.setVisibility(View.VISIBLE);
//Keep this as last statement in onClick
notifyDataSetChanged();
}
});
//and other listeners below
}
Let me know your further response.
Based on #Hari N Jha's Answer.
Call notifyDataSetChanged() when you update anything. E.g
int selectedPosition = -1;
#Override
public void onBindViewHolder(MyViewHolder holder, int position) {
//....
if(position == selectedPosition) {
//Add background color change of your layout or as you want for selected item.
} else {
//Add background color change of your layout or as you want for default item.
}
notifyDataSetChanged(); //Call notifyDataSetChanged() here after done all the stufs
//...
}
Does anyone knows how to access adapter imageView inside activity to hide the view. Please specify any example.
I hope this will work for you.
By using SharedPreferences we can easily hide the view from activity or fragment.
Save flag in SharedPreferences i.e true from activity.
If you are using Recyclerview then in onBindViewHolder method check condition
if(flag==true){
holder.yourView.setVisibility(View.GONE);
}else{
holder.yourView.setVisibility(View.VISIBLE);
}
Go to onBindViewHolder of the adapter and take the id of your imageview and code like this
holder.mImgVw.setVisibility(View.GONE);
You should not directly interact with the ImageView, instead you can use notifyItemChanged() to update the ImageView state in the Adapter. But, you need to slightly modify your Adapter code by adding a flag in your model data or using SparseBooleanArray as a mechanism to saving the ImageView state.
Here the example:
public class Adapter ... {
private SparseBooleanArray mSelectedItems;
private List<YourModel> mItems;
public Adapter(List<YourModel> items) {
mItems = items;
mSelectedItems = new SparseBooleanArray();
}
...
public void onBindViewHolder(....) {
int itemPosition = viewHolder.getAdapterPosition();
YourModel item = items.get(itemPosition);
boolean visible = mSelectedItems.get(itemPosition);
viewHolder.imageView.setVisibility(visible? View.VISIBLE: View.GONE);
...
}
public void setItemVisibilityByPosition(int position, boolean visible) {
mSelectedItems.put(position, visible);
notifyItemChanged(position);
}
}
You can change the image visibility with:
// Assume the mAdapter is your Adapter
mAdapter.setItemVisibilityByPosition(5, true);
I have a RecyclerView with a Horizontal LinerLayout. It displays numbers from 10 to 1, that is used to rate something.
When I select 10 and scroll back to 1 and select 1. I have to update the UI to remove selection on 10 and update selection on 1. But, when I use findViewHolderForAdapterPosition() to remove the selection on 10 it gives me a NullPointerException
I am getting the position in the ViewHolder with getAdapterPosition().
Then, I use that position to get the ViewHolder by calling findViewHolderForAdapterPosition() on my recycler view object and update the UI to remove the selection from 10.
vh = (RatingRecyclerAdapter.ViewHolder)
mRecycler.findViewHolderForAdapterPosition(previousPosition);
vh.textRating.setBackgroundResource(R.drawable.rating_background_selected_orange);;
With some tests, I found out when I try to do the same thing without scrolling it works fine. However, only when I am scrolling it gives me a NullPointerException
How do I fix this?
As requested here is some important code from Adapter class.
#Override
public void onBindViewHolder(RatingRecyclerAdapter.ViewHolder holder, int position) {
String itemText = itemList.get(position);
holder.textRating.setText(itemText);
}
public class ViewHolder extends RecyclerView.ViewHolder {
TextView textRating;
public ViewHolder(View itemView) {
super(itemView);
textRating = (TextView) itemView.findViewById(R.id.text_rating);
textRating.setOnClickListener(ratingClickListener);
}
private final View.OnClickListener ratingClickListener = new View.OnClickListener() {
#Override
public void onClick(View v) {
int position = getAdapterPosition();
if (callback != null) {
callback.onClickRating(v, position);
}
}
};
}
Activity Class
#Override
public void onClickRating(View view, int position) {
RatingRecyclerAdapter.ViewHolder vh;
int color;
int previousPosition = mAdapter.getSelectedPosition(); //Get previously clicked postion if any.
if (previousPosition == Constants.NO_ITEM_SELECTED) {
// An item was selected first time
vh = (RatingRecyclerAdapter.ViewHolder)
mRecycler.findViewHolderForAdapterPosition(position);
mAdapter.setSelectedPosition(position); // Save new item selected position.
color = Utility.getItemColor(mAdapter.getSelectedRating());
mAdapter.setSelectedRatingResource(vh, color);
return;
}
if (position == previousPosition) // Same item was selected
return;
vh = (RatingRecyclerAdapter.ViewHolder)
mRecycler.findViewHolderForAdapterPosition(previousPosition);
color = Utility.getItemColor(mAdapter.getSelectedRating());
mAdapter.setUnselectedRatingResource(vh, color); // Remove the previous selected item drawables.
vh = (RatingRecyclerAdapter.ViewHolder)
mRecycler.findViewHolderForAdapterPosition(position);
mAdapter.setSelectedPosition(position); // Save new item selected position.
color = Utility.getItemColor(mAdapter.getSelectedRating());
mAdapter.setSelectedRatingResource(vh, color); // Set the new selected item drawables. Setting some background to indicate selection.
}
As Sevastyan has written in the comment, the RecyclerView immediately recycles the view as soon as the item is out of the screen. So if we call findViewHolderForAdapterPosition() for a view which is outside the screen we get a null value. (I am not confirming this is the actual case. But, this is what it seems to me.)
So I created a class that stores all the data about an item in the RecyclerView and stored all the colours and value of that item in the class. And when we are populating the view, set the all the colours based on data stored in that class.
PS: I THANK Sevastyan for not giving me the answer directly. But, only giving me the reason for getting that Exception.
If your view is out of the screen, it can be recycled OR cached.
In case it's recycled, you can handle in onViewRecycled() method or setup the view again inside onBind() when the view becomes visible (you can save the state on the object of your list if needed).
In case it's not recycled (onViewRecycled method not called for that position), it's probably cached. You can set the cache size to zero to prevent this state from happening.
recycler.setItemViewCacheSize(0)
I have a listview in fragment.
When I select a listview item, it gets highlighted and then I open another fragment.
Now, what I want is, when I move back to previous fragment, the list item should stay selected.
How can I do that?
I have implemented like
add this two methods in your Adapter
private int selectedIndex = ListView.NO_ID;
public int getSelectedIndex() {
return selectedIndex;
}
public void setSelectedIndex(int index) {
this.selectedIndex = index;
// Re-draw the list by informing the view of the changes
notifyDataSetChanged();
}
and in your Adapter getView(...) do
// Highlight the selected item in the list
if (selectedIndex != -1 && selectedIndex == position) {
YourView.setBackgroundResource(R.color.lightred);
}
and implement in Fragment in setOnItemClickListener onItemClick(...) like
adapter.setSelectedIndex(position);
save this selected value in some preferences and when you come back again call in Fragment on resume(...)
adapter.setSelectedIndex(selectedIndex);
OK let's do this
declare one field in your adapter say
private int selectedPosition=-1;
now create a setter for this
private void setSelectedPosition(int position)
{
selectedPosition=position;
}
Now in your getView method
if(position==selectedPosition)
{
listItemView.setSelected(true);
//OR
listItemView.setBackgroundColor(<Some Color>);
}
Now after setting the adapter when user tap and your OnItmeSelected called
adapter.setSelectedPosition(<your desired selected item position>);
adapter.notifyDataSetChanged();