Develop Reference

Android RecyclerView Custom Image Displaying

I have a recyclerview which displays data from an SQLite database.
I have a list of icons that I save in an ArrayList and apply color to them inside the ArrayList too.
Example: mMoodIcons.add(new MoodIcons(R.drawable.excited_icon, R.mipmap.background_clouds_excited, ContextCompat.getColor(mContext, R.color.excited), mContext.getString(R.string.excited)));
In the recycerview I have this code:
if(currentLog.getMoodBefore() == 3){
holder.moodIcon.setImageResource(R.drawable.confident_icon);
holder.moodIcon.setColorFilter(ContextCompat.getColor(mContext, R.color.confident));
}
I need to make it dynamic so, for example, each mood has a number 1 = happy, 2 = fine, etc
So when the recycler view is displaying the information from the log it can display the correct mood icon with the color applied.
Could someone help me with the logic to write this code? I'm hitting a wall.
EDIT: The way I have it written above works in the if statement. But that would require 18 if statements. Is there a slicker way of writing this, maybe using an arraylist and a for loop?

I solved this myself. I created an arraylist of the mood icons and colors. Then I used this code:
for (MoodIconsWorkoutLog moodBefore : moodIcons) {
if(moodBefore.getMoodBefore() == currentLog.getMoodBefore() ){
holder.moodIcon.setImageResource(moodBefore.getMoodImage());
holder.moodIcon.setColorFilter(moodBefore.getColour());
}
}
Worked perfectly

View not hiding when dynamically done in recycler view item

I am using RecyclerView to list Items and In each single list displaying an image which will be Visible/Gone dynamically. I am using View.GONE to hide the view.
In a condition where the image should hide is not working always. It is still showing in screen,and also in debug mode i have checked that and when getting the
image.getVisiblity() it is giving me int value "8" which means the view is Gone,But still i can see that image in that list.
It happens only sometimes.
And i tried to use View.INVISIBLE and it is working all the time but it is taking the space in layout which is as expected
I am using sparseArray to store all the holders classes.I have written a method in Adapter and calling this from activity.I am trying to hide the replayIcon view
public void handleReplayButton(int pos,Boolean isDisplay) {
Holder holder = holderSparseArray.get(pos);
if(holder != null) {
if (isDisplay != null && isDisplay == true) {
holder.playIcon.setVisibility(View.GONE);
holder.pauseIcon.setVisibility(View.GONE);
holder.replayIcon.setVisibility(View.VISIBLE);
} else if(isDisplay != null && isDisplay == false) {
holder.playIcon.setVisibility(View.VISIBLE);
holder.pauseIcon.setVisibility(View.GONE);
holder.replayIcon.setVisibility(View.GONE);
} else {
holder.playIcon.setVisibility(View.GONE);
holder.pauseIcon.setVisibility(View.VISIBLE);
holder.replayIcon.setVisibility(View.GONE);
}
}
}
Here it is going to the last else statement what i want and it is setting the view to GONE.and when i call holder.replayIcon.getVisibility() it is giving me int 8 but,still i can see the icon

Try calling invisible at the end of one statement which makes it visible and vice versa.
Or
You can also try to put notifydatasetchanged().

You will have to call notifyDataSetChanged() to refresh the list in the recycler view.
But since you have to remove an item, you can also use notifyItemRemoved
Also, if you are using setVisibility() method to HIDE the view, then make sure you also set the view as VISIBLE for valid items, because the items are reused in a recycler view.
For more : https://developer.android.com/reference/android/support/v7/widget/RecyclerView.Adapter

If you will call notifyDataSetChanged() - it will update all the items in the list.
Don't do that if you need to update special items by index because it will take a lot of memory to redraw the all views.
Instead like the guys wrote before you should use notifyItemChanged(), notifyItemInserted() or notifyItemRemoved().
If you want to update couple views use can use notifyItemRangeChanged(), notifyItemRangeRemoved() or notifyItemRangeInserted().
You can read more about it here
Also there is one way to it. You can use DiffUtils callbacks.
Pretty good approach that work with animation already.
DiffUtils Calbacks

Setting RecyclerViews itemAnimator to null does not remove animations

My outer RecyclerView crashes either with
IllegalArgumentException: Scrapped or attached views may not be recycled. isScrap:false isAttached:true...
or
IllegalStateException: The specified child already has a parent. You must call removeView() on the child's parent first.
Like the title suggests I have an RecyclerView in the list item layout of the first RecyclerView. This layout is used to display messages and the
inner RecyclerView to display attachments that come with the message. The inner RecyclerViews visibility is set to either GONE or VISIBLE depending whether the message has any attachments or not. The simplified outer list item layout looks like this
ConstraintLayout
TextView
TextView
TextView
RecyclerView
And the part of the adapter that handles the inner RecyclerView looks like this
private fun bindFiles(message: Message?) = with(itemView) {
if (message != null && message.attachments.isNotEmpty())
{
sent_message_attachments.setAsVisible()
sent_message_attachments.layoutManager = GridLayoutManager(this.context,Math.min(message.attachments.size,3))
sent_message_attachments.adapter = AttachmentAdapter(message.attachments)
sent_message_attachments.itemAnimator = null
sent_message_attachments.setHasFixedSize(true)
}
else{
sent_message_attachments.setAsGone()
sent_message_attachments.adapter = null
sent_message_attachments.layoutManager = null
}
}
The bug has something to do with the way I fetch the attachments in the inner adapter since once I disable the part that start the download process, everything is fine. There's no problem when loading images from the device, but once I start the download process, everything goes to hell. This is the part that handles images and kicks off the download process in the inner adapter. I have functions for videos and for other file types that are pretty much the same exact thing but use slightly different layout.
private fun bindImage(item: HFile?) = with(itemView) {
if (item != null)
{
if (item.isOnDevice && !item.path.isNullOrEmpty())
{
if (item.isGif)
{
attachment_image.displayGif(File(item.path))
}
else
{
attachment_image.displayImage(File(item.path))
}
}
else
{
//TODO: Add option to load images manually
FileHandler(item.id).downloadFileAsObservable(false)
.subscribeOn(Schedulers.io())
.observeOn(AndroidSchedulers.mainThread())
.subscribe(
{ progress ->
//TODO: Show download process
},
{ error ->
error.printStackTrace()
//TODO: Enable manual retry
},
{ notifyItemChanged(adapterPosition)} //onComplete
)
}
}
}
I use the same structure as above in my DiscussionListAdapter to load discussion portraits (profile pictures etc.) and it does not have the same issue.
These are the extensions functions used to inflate the viewHolders and to display the images
fun ViewGroup.inflate(layoutRes: Int): View
{
return LayoutInflater.from(context).inflate(layoutRes, this, false)
}
fun ImageView.displayGif(file:File){
GlideApp.with(context).asGif().load(file).transforms(CenterCrop(), RoundedCorners(30)).into(this)
}
fun ImageView.displayImage(file:File){
GlideApp.with(context).load(file).transforms(CenterCrop(), RoundedCorners(30)).into(this)
}
I've been on this for the past couple of days and just can't get my head around it. Any help in any direction is greatly appreciated. I know my explanations can be a bit all over the place so just ask for clarification when needed :)
UPDATE
I have now been able to produce this with a GridLayout as well as with RecyclerView. It's safe to assume that the nested RecyclerViews were not the culprit here. I even tried to ditch the Rx-piece that handled loading the images and created an IntentService for the process, but the same crashes still occur.
With GridLayout I mean that instead of having another adapter to populate the nested RecyclerView I use only one adapter to populate the message and to inflate and populate views for the attachments as well and to attach those views to the nested GridLayout.
The crash happens when I start to download a file and then scroll the view, that is supposed to show the downloaded file, out of the screen. That view should get recycled but for some reason the download process (which in my test cases only takes around 100ms-400ms) causes the app to throw one of the two errors mentioned in the original question. It might be worth noting that I'm using Realm and the adapter takes in a RealmResults<Message> list as it's dataset. My presenter looks for changes in the list and then notifies the adapter when needed (changed due to the implementation of IntentService).
This is how I'm capable to reproduce this time and time again:
Open a discussion that has messages with attachments
Start to scroll upwards for more messages
Pass a message with an attachment and scroll it off screen while it's still loading
Crash
There is no crash if I stop and wait for the download to complete and everything works as intended. The image/video/file gets updated with a proper thumbnail and the app wont crash if I scroll that out of view.
UPDATE 2
I tried swapping the nested ViewGroup for a single ImageView just to see is the problem within the nestedness. Lo and behold! It still crashes. Now I'm really confused, since the DiscussionListAdapter I mentioned before has the same exact thing in it and that one works like a charm... My search continues. I hope someone, some day will benefit from my agony.
UPDATE 3
I started to log the parent of every ViewHolder in the onBindViewHolder() function. Like expected I got nulls after nulls after nulls, before the app crashed and spew this out.
04-26 21:54:50.718 27075-27075/com.hailer.hailer.dev D/MsgAdapter: Parent of ViewHolder: android.view.ViewOverlay$OverlayViewGroup{82a9fbc V.E...... .......D 0,0-1440,2168}
There's a method to my madness after all! But this just poses more questions. Why is ViewOverlay used here? As a part of RecyclerView or as a part of the dark magicians plans to deprive me of my sanity?
Sidenote
I went digging into RecyclerViews code to check if I could find a reason for the ViewOverlaymystery. I found out that RecyclerView calls the adapters onCreateViewHolder() function only twice. Both times providing itself as the parent argument for the function. So no luck there... What the hell can cause the item view to have the ViewOverlay as it's parent? The parent is an immutable value, so the only way for the ViewOverlay to be set as the parent, is for something to construct a new ViewHolder and supply the ViewOverlay as the parent object.
UPDATE 4
Sometimes I amaze myself with my own stupidity. The ViewOverlay is used because the items are being animated. I didn't even consider this to be an option since I've set the itemAnimator for the RecyclerView as null, but for some odd reason that does not work. The items are still being animated and that is causing this whole charade. So what could be the cause of this? (How I chose to ignore the moving items, I do not know, but the animations became very clear when I forced the app to download same picture over and over again and the whole list went haywire.)
My DiscussionInstanceFragment contains the RecyclerView in question and a nested ConstraintLayout that in turn contains an EditText for user input and a send button.
val v = inflater.inflate(R.layout.fragment_discussion_instance, container, false)
val lm = LinearLayoutManager(context)
lm.reverseLayout = true
v.disc_instance_messages_list.layoutManager = lm
v.disc_instance_messages_list.itemAnimator = null
v.disc_instance_messages_list.adapter = mPresenter.messageAdapter
This is the piece that handles the initialization of the RecyclerView. I'm most definitely setting the itemAnimator as null, but the animations just wont stop! I've tried setting the animateLayoutChanges xml attribute on the root ConstraintLayout and on the RecyclerView but neither of them worked. It's worth mentioning that I also checked whether the RecyclerView had an itemAnimator in different states of the program, and every time I check the animator, it is null. So what is animating my RecyclerView?!

I have faced the same issue
Try this in your child RecyclerView it works for me
RecyclerView childRC = itemView.findViewById(R.id.cmol_childRC);
layoutManager = new LinearLayoutManager(context);
childRC.setItemAnimator(null);
childRC.setLayoutManager(layoutManager);
childRC.setNestedScrollingEnabled(false);
childRC.setHasFixedSize(true);
now set your Adapter like this
ArrayList<Model> childArryList = new ArrayList<>();
childArryList.addAll(arrayList.get(position).getArrayList());
ChildOrderAdapter adapter = new ChildOrderAdapter(context, childArryList);
holder.childRC.swapAdapter(adapter, true);
hope this helps

I finally figured out what was causing this. In my DiscussionInstanceView I have a small view that is animated into and out of view with ConstraintLayout keyframe animations. This view only shows the download progress of the chat history and is used only once, when the discussion is first opened. BUT since I had a call to hiding that view every time my dataset got updated, I was forcing the ConstraintLayout to fire of an animation sequence thus making everything animate during the dataset update. I just added a simple check whether I was downloading the history or not and this problem got fixed.

Android: Detect if a ListView has the scrollbar (after setting new data)

I have an ArrayAdapter linked to a ListView.
mListView.setAdapter(mArrayAdapter);
Whenever I reset the ArrayList data to the ArrayAdapter:
mArrayAdapter.clear();
mArrayAdapter.addAll(mArrayList);
mArrayAdapter.notifyDataSetChanged()
the ListView gets correctly updated
however, if just after the above three lines, I call my custom method mListView.hasScrollbar() to detect whether the listview has a scrollbar or not, I get a null lastVisibleItem:
public boolean hasScrollbar() {
View lastVisibleItem = (View) getChildAt(getChildCount() - 1);
if (lastVisibleItem.getBottom()>=getHeight()) {
return true;
}
return false;
}
does it mean that the listview is still refreshing?
My main question is:
how can I test if the listview has the scrollbar after resetting the adapter with new data?
thank you for any help!

Using getLastVisiblePosition / getFirstVisiblePosition is a valid method of detecting wether you have scrolling or not within the list view (aslong as you compare it to getCount() and do your math ofc).
The problem you have as you already guess is that you are attempting to check out of sync.
In order to sync your query when the adapter already filled your List Data and updated changes, you need to issue a post request to the list, which will stack that petition to the message queue of the adapter.
yourAdapter.notifyDataSetChanged();
yourAdapter.getListView().post(new Runnable() {
#Override public void run() {
//your code here
}
});
Make sure to call that after notifySetDataChanged() of course. Because you want the list to update before the check.

I think your question equals to "how to tell if list view contains items need to displayed on more than one screen"?
So my suggestion is to use listView.getFirstVisiblePosition() and getLastVisiblePosition() to tell it.

Android, Adapter: Filtering via getView() still leaves gray lines

My application uses a list of media files on the phone, i.e. images, audio and video. It also allows the user to filter the list via some checkboxes in a menu, so the user can choose to show or hide each type of files.
The way I've been doing this is by putting this in the adapter's getView():
// don't show unwanted file types
if (cmo.hasType(MediaType.AUDIO_FILE)){
if(!prefs.getBoolean(PREFS_SHOWAUDIO, true)){
return new ViewStub(mContext);;
}
}else if(cmo.hasType(MediaType.IMAGE_FILE)){
if(!prefs.getBoolean(PREFS_SHOWIMG, true)){
return new ViewStub(mContext);;
}
}else if( cmo.hasType(MediaType.VIDEO_FILE)){
if(!prefs.getBoolean(PREFS_SHOWVIDEO, true)){
return new ViewStub(mContext);;
}
}
which is quite effective in the sense that the list doesn't show those elements. However, the ListView still renders a 1px grey line between each View, even if they are ViewStubs, meaning I see a thick grey line whenever a group of consecutive items are filtered away.
How can I get rid of those lines? Should I create a new data array, containing only the elements that should show a view?

I think Adapter isn't a good place to add list logic. It's for fetching and displaying data, not for making decisions, what to show/hide. As you can see there is no way to not add a View for given index (in getView() method).
You should filter your list before you will pass it to an Adapter.