Develop Reference

How to loop on data while inflating layouts?

Do I have to rely on ListView/Recycler view each time I need to loop over data to repeat a layout ?
I totally understand it for long lists of data where scroll/performance is involved, but let's say I am sure i'll only have 0...3max items and need to display in very simple single-line-layout for each (1 image, 1 textview + button).. isn't there a simplier pattern than using adapters ?
Seems like overkill (and a pain to deal with for every little part of my screen where I need to loop overs small lists).
What are the other options while using Components architecture (databinding) ?
Manually inflating my layout ? In viewmodel ? fragment? Do I need to create another viewModel specially for this child layout ?
Thanks

I recently have a similar issue recently, but my problem was that of nested lists i.e. I needed to inflate another list inside a recycler view. Here is a minimal example of how I went about it.
Add a LinearLayout to your layout XML file:
<LinearLayout
android:id="#+id/smallList"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="vertical"
app:list="#{viewModel.yourList}" />
Create a binding adapter where you inflate the items. Like so:
#BindingAdapter("app:list")
fun setList(layout: LinearLayout, yourList: List<ListItemModel>) {
layout.removeAllViews() // Remove previous items if your list does change
for (listItem in yourList) {
ListItemBinding.inflate( // inflate your list item
LayoutInflater.from(layout.context),
layout, // pass your LinearLayout as root
true // attachToRoot is true so that the inflated view is added to the LinearLayout
).apply {
// set your binding variables
this.listItem = listItem
}
}
}
Note: This is a minimal example to solve the issue since actual data and functionality is unknown. You may want to:
Add a click listener variable to your list item XML file and set that similarly.
Create a custom view for the view if it is to be reused and write the binding adapter there.

Can you save Recyclerview position to a variable?

I am working on a simple eReader app. One of the things I need to do is save the position the user was at last for each ebook. To display the ebook I am using a Recyclerview for the text (it's just a Recyclerview displaying raw text).
I am not very familiar with Recyclerview, but from what I've read it seems saving the scroll position is possible. However, in most examples it shows it being used in a save/restore state context. What I need to do is save the position for each book.
Is it possible to save the position into some variable which can be loaded when the book is opened again? The way I am handling the books is using a custom object that contains the title and the actual text of the book. I would like to save the position into a variable inside these custom objects, for each individual book. So that when that object's text is displayed, it will go back to the last position.

You can get the recycler view position by:
GridLayoutManager layoutManager = ((GridLayoutManager)mRecyclerView.getLayoutManager());
int recyclerPosition = layoutManager.findFirstVisibleItemPosition();
and then you can save the position in sharedpreferences
and in onCreate or onResume you can call:
mRecyclerView.setPosition(recyclerPosition);

First of all, I'm not sure if using Recyclerview just for the mere purpose of displaying text is right. Recyclerview is used for more sophisticated uses like displaying lists with custom views etc. You can directly use TextView for this purpose.
What you can do it, create a ScrollView, then under it create one child vertical Linear Layout and then keep the TextView as child of this LinearLayout.
Something like this :
<ScrollView
android:layout_width="match_parent"
android:layout_height="match_parent">
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="vertical">
<TextView
android:layout_width="match_parent"
android:layout_height="wrap_content">
</LinearLayout>
</ScrollView>
Now, to know the position of the ScrollView, you can use getScrollY() on your ScrollView

holder.lay_item.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View view) {
if(holder.lay_item.isSelected()) {
holder.lay_item.setSelected(false);
foodAlergies.get(position).setFlag(false);
} else {
holder.lay_item.setSelected(true);
foodAlergies.get(position).setFlag(true);
}
String type="";
int child_position=-1;
itemClickListener.recyclerViewClicked(type,position,child_position);
}
});
public void recyclerViewClicked(String type, int position, int child_position) {
// String prodctid = searchdata.get(position).getId();
}
happy coding

Android ListView with EditText focus issues [duplicate]

I've spent about 6 hours on this so far, and been hitting nothing but roadblocks. The general premise is that there is some row in a ListView (whether it's generated by the adapter, or added as a header view) that contains an EditText widget and a Button. All I want to do is be able to use the jogball/arrows, to navigate the selector to individual items like normal, but when I get to a particular row -- even if I have to explicitly identify the row -- that has a focusable child, I want that child to take focus instead of indicating the position with the selector.
I've tried many possibilities, and have so far had no luck.
layout:
<ListView
android:id="#android:id/list"
android:layout_height="fill_parent"
android:layout_width="fill_parent"
/>
Header view:
EditText view = new EditText(this);
listView.addHeaderView(view, null, true);
Assuming there are other items in the adapter, using the arrow keys will move the selection up/down in the list, as expected; but when getting to the header row, it is also displayed with the selector, and no way to focus into the EditText using the jogball. Note: tapping on the EditText will focus it at that point, however that relies on a touchscreen, which should not be a requirement.
ListView apparently has two modes in this regard:
1. setItemsCanFocus(true): selector is never displayed, but the EditText can get focus when using the arrows. Focus search algorithm is hard to predict, and no visual feedback (on any rows: having focusable children or not) on which item is selected, both of which can give the user an unexpected experience.
2. setItemsCanFocus(false): selector is always drawn in non-touch-mode, and EditText can never get focus -- even if you tap on it.
To make matters worse, calling editTextView.requestFocus() returns true, but in fact does not give the EditText focus.
What I'm envisioning is basically a hybrid of 1 & 2, where rather than the list setting if all items are focusable or not, I want to set focusability for a single item in the list, so that the selector seamlessly transitions from selecting the entire row for non-focusable items, and traversing the focus tree for items that contain focusable children.
Any takers?

This helped me.
In your manifest :
<activity android:name= ".yourActivity" android:windowSoftInputMode="adjustPan"/>

Sorry, answered my own question. It may not be the most correct or most elegant solution, but it works for me, and gives a pretty solid user experience. I looked into the code for ListView to see why the two behaviors are so different, and came across this from ListView.java:
public void setItemsCanFocus(boolean itemsCanFocus) {
mItemsCanFocus = itemsCanFocus;
if (!itemsCanFocus) {
setDescendantFocusability(ViewGroup.FOCUS_BLOCK_DESCENDANTS);
}
}
So, when calling setItemsCanFocus(false), it's also setting descendant focusability such that no child can get focus. This explains why I couldn't just toggle mItemsCanFocus in the ListView's OnItemSelectedListener -- because the ListView was then blocking focus to all children.
What I have now:
<ListView
android:id="#android:id/list"
android:layout_height="match_parent"
android:layout_width="match_parent"
android:descendantFocusability="beforeDescendants"
/>
I use beforeDescendants because the selector will only be drawn when the ListView itself (not a child) has focus, so the default behavior needs to be that the ListView takes focus first and draws selectors.
Then in the OnItemSelectedListener, since I know which header view I want to override the selector (would take more work to dynamically determine if any given position contains a focusable view), I can change descendant focusability, and set focus on the EditText. And when I navigate out of that header, change it back it again.
public void onItemSelected(AdapterView<?> listView, View view, int position, long id)
{
if (position == 1)
{
// listView.setItemsCanFocus(true);
// Use afterDescendants, because I don't want the ListView to steal focus
listView.setDescendantFocusability(ViewGroup.FOCUS_AFTER_DESCENDANTS);
myEditText.requestFocus();
}
else
{
if (!listView.isFocused())
{
// listView.setItemsCanFocus(false);
// Use beforeDescendants so that the EditText doesn't re-take focus
listView.setDescendantFocusability(ViewGroup.FOCUS_BEFORE_DESCENDANTS);
listView.requestFocus();
}
}
}
public void onNothingSelected(AdapterView<?> listView)
{
// This happens when you start scrolling, so we need to prevent it from staying
// in the afterDescendants mode if the EditText was focused
listView.setDescendantFocusability(ViewGroup.FOCUS_BEFORE_DESCENDANTS);
}
Note the commented-out setItemsCanFocus calls. With those calls, I got the correct behavior, but setItemsCanFocus(false) caused focus to jump from the EditText, to another widget outside of the ListView, back to the ListView and displayed the selector on the next selected item, and that jumping focus was distracting. Removing the ItemsCanFocus change, and just toggling descendant focusability got me the desired behavior. All items draw the selector as normal, but when getting to the row with the EditText, it focused on the text field instead. Then when continuing out of that EditText, it started drawing the selector again.

My task was to implement ListView which expands when clicked. The additional space shows EditText where you can input some text. App should be functional on 2.2+ (up to 4.2.2 at time of writing this)
I tried numerous solutions from this post and others I could find; tested them on 2.2 up to 4.2.2 devices.
None of solutions was satisfactionary on all devices 2.2+, each solution presented with different problems.
I wanted to share my final solution :
set listview to android:descendantFocusability="afterDescendants"
set listview to setItemsCanFocus(true);
set your activity to android:windowSoftInputMode="adjustResize"
Many people suggest adjustPan but adjustResize gives much better ux imho, just test this in your case. With adjustPan you will get bottom listitems obscured for instance. Docs suggest that ("This is generally less desirable than resizing"). Also on 4.0.4 after user starts typing on soft keyboard the screen pans to the top.
on 4.2.2 with adjustResize there are some problems with EditText focus. The solution is to apply rjrjr solution from this thread. It looks scarry but it is not. And it works. Just try it.
Additional 5. Due to adapter being refreshed (because of view resize) when EditText gains focus on pre HoneyComb versions I found an issue with reversed views:
getting View for ListView item / reverse order on 2.2; works on 4.0.3
If you are doing some animations you might want to change behaviour to adjustPan for pre-honeycomb versions so that resize doesnt fire and adapter doesn't refresh the views. You just need to add something like this
if(android.os.Build.VERSION.SDK_INT < android.os.Build.VERSION_CODES.HONEYCOMB)
getWindow().setSoftInputMode(WindowManager.LayoutParams.SOFT_INPUT_ADJUST_PAN);
All this gives acceptable ux on 2.2 - 4.2.2 devices.
Hope it will save people some time as it took me at least several hours to come to this conclusion.

This saved my life--->
set this line
ListView.setDescendantFocusability(ViewGroup.FOCUS_AFTER_DESCENDANTS);
Then in your manifest in activity tag type this-->
<activity android:windowSoftInputMode="adjustPan">
Your usual intent

We're trying this on a short list that does not do any view recycling. So far so good.
XML:
<RitalinLayout
android:layout_width="match_parent"
android:layout_height="match_parent"
>
<ListView
android:id="#+id/cart_list"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:scrollbarStyle="outsideOverlay"
/>
</RitalinLayout>
Java:
/**
* It helps you keep focused.
*
* For use as a parent of {#link android.widget.ListView}s that need to use EditText
* children for inline editing.
*/
public class RitalinLayout extends FrameLayout {
View sticky;
public RitalinLayout(Context context, AttributeSet attrs) {
super(context, attrs);
ViewTreeObserver vto = getViewTreeObserver();
vto.addOnGlobalFocusChangeListener(new ViewTreeObserver.OnGlobalFocusChangeListener() {
#Override public void onGlobalFocusChanged(View oldFocus, View newFocus) {
if (newFocus == null) return;
View baby = getChildAt(0);
if (newFocus != baby) {
ViewParent parent = newFocus.getParent();
while (parent != null && parent != parent.getParent()) {
if (parent == baby) {
sticky = newFocus;
break;
}
parent = parent.getParent();
}
}
}
});
vto.addOnGlobalLayoutListener(new ViewTreeObserver.OnGlobalLayoutListener() {
#Override public void onGlobalLayout() {
if (sticky != null) {
sticky.requestFocus();
}
}
});
}
}

this post was matching exactly my keywords. I have a ListView header with a search EditText and a search Button.
In order to give focus to the EditText after loosing the initial focus the only HACK that i found is:
searchText.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View arg0) {
// LOTS OF HACKS TO MAKE THIS WORK.. UFF...
searchButton.requestFocusFromTouch();
searchText.requestFocus();
}
});
Lost lots of hours and it's not a real fix. Hope it helps someone tough.

If the list is dynamic and contains focusable widgets, then the right option is to use RecyclerView instead of ListView IMO.
The workarounds that set adjustPan, FOCUS_AFTER_DESCENDANTS, or manually remember focused position, are indeed just workarounds. They have corner cases (scrolling + soft keyboard issues, caret changing position in EditText). They don't change the fact that ListView creates/destroys views en masse during notifyDataSetChanged.
With RecyclerView, you notify about individual inserts, updates, and deletes. The focused view is not being recreated so no issues with form controls losing focus. As an added bonus, RecyclerView animates the list item insertions and removals.
Here's an example from official docs on how to get started with RecyclerView: Developer guide - Create a List with RecyclerView

some times when you use android:windowSoftInputMode="stateAlwaysHidden"in manifest activity or xml, that time it will lose keyboard focus. So first check for that property in your xml and manifest,if it is there just remove it. After add these option to manifest file in side activity android:windowSoftInputMode="adjustPan"and add this property to listview in xml android:descendantFocusability="beforeDescendants"

Another simple solution is to define your onClickListener, in the getView(..) method, of your ListAdapter.
public View getView(final int position, View convertView, ViewGroup parent){
//initialise your view
...
View row = context.getLayoutInflater().inflate(R.layout.list_item, null);
...
//define your listener on inner items
//define your global listener
row.setOnClickListener(new OnClickListener(){
public void onClick(View v) {
doSomethingWithViewAndPosition(v,position);
}
});
return row;
That way your row are clickable, and your inner view too :)

The most important part is to get the focus working for the list cell.
Especially for list on Google TV this is essential:
setItemsCanFocus method of the list view does the trick:
...
mPuzzleList = (ListView) mGameprogressView.findViewById(R.id.gameprogress_puzzlelist);
mPuzzleList.setItemsCanFocus(true);
mPuzzleList.setAdapter(new PuzzleListAdapter(ctx,PuzzleGenerator.getPuzzles(ctx, getResources(), version_lite)));
...
My list cell xml starts like follows:
<?xml version="1.0" encoding="utf-8"?>
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:id="#+id/puzzleDetailFrame"
android:focusable="true"
android:nextFocusLeft="#+id/gameprogress_lessDetails"
android:nextFocusRight="#+id/gameprogress_reset"
...
nextFocusLeft/Right are also important for D-Pad navigation.
For more details check out the great other answers.

I just found another solution. I believe it's more a hack than a solution but it works on android 2.3.7 and android 4.3 (I've even tested that good old D-pad)
init your webview as usual and add this: (thanks Michael Bierman)
listView.setItemsCanFocus(true);
During the getView call:
editText.setOnFocusChangeListener(
new OnFocusChangeListener(View view,boolean hasFocus){
view.post(new Runnable() {
#Override
public void run() {
view.requestFocus();
view.requestFocusFromTouch();
}
});

Just try this
android:windowSoftInputMode="adjustNothing"
in the
activity
section of your manifest.
Yes, it adjusts nothings, which means the editText will stay where it is when IME is opening. But that's just an little inconvenience that still completely solves the problem of losing focus.

In my case, there is 14 input edit text in the list view. The problem I was facing, when the keyboard open, edit text focus lost, scroll the layout, and as soon as focused view not visible to the user keyboard down. It was not good for the user experience. I can't use windowSoftInputMethod="adjustPan". So after so much searching, I found a link that inflates custom layout and sets data on view as an adapter by using LinearLayout and scrollView and work well for my case.

listview on click to edit

I have set up a listview with one edit text widget. The listview is populated with a string file and I wanted to make changes on each item by clicking on the item. code builds and the listview shows as planned. When the item is clicked it gets focus but then looses focus after the keyboard pops up without any entries.
els_edit_tiles.xml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical" >
<EditText
android:id="#+id/listText"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:ems="10" >
</EditText>
This is the onclicklistener, I assume the changes will need to be here and did not post the adapter code.
private class ListClickhandler implements OnItemClickListener {
#Override
public void onItemClick(AdapterView<?> Adapter, View view, int position, long arg3) {
TextView listText = (TextView) view.findViewById(R.id.listText);
String text = listText.getText().toString();
// Toast.makeText(context, text + " " + position, Toast.LENGTH_LONG).show();
}
}

I assume you mean the item loses its highlight, rather than focus. Focus goes wherever you tap and is there whether the highlight shows or not. So, I'll explain some options for the disappearing highlight.
For better or worse, they've designed it this way. You have a few choices. One is to subclass ListView and try to figure out how to add a sticky highlight. (I tried that and got it to work, but abandoned it for another reason - I wanted to put the list in a ScrollView, which doesn't work with a ListView).
Another choice: use a spinner (aka a drop down list). This doesn't exactly do what you're asking but it does show you which item was selected -- it is the one that shows when the spinner collapses.
Yet a third choice (I implemented this) - Use a LinearLayout and add each item as a child of the layout. You have to implement your own selection and highlighting, but that takes relatively little code (I can help if you need). This effectively gives you a list that shows all items - it doesn't scroll. You can include it in a ScrollView along with other elements to scroll the whole collection together.

Remove header from listView

I'm having some problems when trying to remove the header from a listView. At first I use addHeaderView() to add it, but when I change to another layout I want it to disappear but removeHeaderView() doesn't work...
I also tried setting visibility to GONE and it doesn't disappear...
What can I do?
Thanks in advance

Try the approach mentioned below..
Android ListView#addHeaderView and ListView#addFooterView methods are strange: you have to add the header and footer Views before you set the ListView's adapter so the ListView can take the headers and footers into consideration -- you get an exception otherwise. Here we add a ProgressBar (spinner) as the headerView:
// spinner is a ProgressBar
listView.addHeaderView(spinner);
We'd like to be able to show and hide that spinner at will, but removing it outright is dangerous because we'd never be able to add it again without destroying the ListView -- remember, we can't addHeaderView after we've it's adapter:
listView.removeHeaderView(spinner); //dangerous!
So let's hide it! Turns out that's hard, too. Just hiding the spinner view itself results in an empty, but still visible, header area.
Now try to hide the spinner:
spinner.setVisibility(View.GONE);
Result: header area still visible with an ugly space:
The solution is to put the progress bar in a LinearLayout that wraps it's content, and hiding the content. That way the wrapping LinearLayout will collapse when its content is hidden, resulting in a headerView that is technically still present, but 0dip high:
<LinearLayout
xmlns:a="http://schemas.android.com/apk/res/android"
android:orientation="vertical"
android:layout_width="fill_parent"
android:layout_height="wrap_content">
<!-- simplified -->
<ProgressBar
android:id="#+id/spinner"
android:layout_width="wrap_content"
android:layout_height="wrap_content"/>
</LinearLayout>
Then, set the layout as the header:
spinnerLayout = getLayoutInflater().inflate(R.layout.header_view_spinner, null);
listView.addHeaderView(spinnerLayout);
And when we need to hide it, hide the layout's content, not the layout:
spinnerLayout.findViewById(R.id.spinner).setVisibility(View.GONE);
Now the header disappears from view. No more ugly space at the top!

Most people don't like to use AddHeaderView, however I sometimes found it very convenient, to avoid modifying complex adapters, or if the headers are not very related to them.
With this easy trick you will be able to seamlessly remove/add headers:
I add an empty LinearLayout with orientation vertical, and height wrap_content, as the only Header View (let mListView be the target listView):
LinearLayout mCustomHeaders=new LinearLayout(context);
mCustomHeaders.setOrientation(LinearLayout.VERTICAL);
mListView.addHeaderView(mCustomHeaders);
mListView.setAdapter (.......)
Thenafter, I can add random stuff, anywhere, to the list as header, even when the list is full:
mCustomHeaders.add(myHeaderView1);
mCustomHeaders.add(myHeaderView2);
mCustomHeaders.add(myHeaderView3);
You can also delete all headers, anytime:
mCustomHeaders.removeAllViews(); // will erase all headers
You get the idea .... Hope it helps !

The problem is that you are always creating a new object when you do:
View headerView = someView
So the new view is not the same as the view already added as listView header, try this:
View headerView = inflater.inflate(R.layout.adapter_datatable_saleitem_header, null, false);
headerView.setTag(this.getClass().getSimpleName() + "header");
if (listView.getHeaderViewsCount() > 0) {
View oldView = listView.findViewWithTag(this.getClass().getSimpleName() + "header");
if (oldView != null) {
listView.removeHeaderView(oldView);
}
}

You can check if header count > 0 then remove the header and add it again.
its works fine for me.
View _headerView;
private void function HandleHeaderView(){
if(listView.getHeaderViewsCount() > 0)
{
listView.removeHeaderView(_headerView);
}
/* Add list view header */
_headerView = GetHeaderView();
listView.addHeaderView(_headerView);
}
private View GetHeaderView()
{
View header = getLayoutInflater().inflate(R.layout.header_layout, null);
// TODO: ...
return header
}

Where drawerLogoView is my headerview, here's what I do:
drawerLogoView = mInflater.inflate(R.layout.navigation_drawer_custom_layout, null);
mDrawerList.addHeaderView(drawerLogoView,null,false);
LinearLayout layOut = ((LinearLayout)drawerLogoView.findViewById(R.id.NavProfilePreviewLayout));
layOut.setLayoutParams(new RelativeLayout.LayoutParams(RelativeLayout.LayoutParams.MATCH_PARENT, 0));
That way, it becomes invisible :D
To show it back, you can use this:
LinearLayout layOut = ((LinearLayout)drawerLogoView.findViewById(R.id.NavProfilePreviewLayout));
layOut.setLayoutParams(newRelativeLayout.LayoutParams(RelativeLayout.LayoutParams.MATCH_PARENT, RelativeLayout.LayoutParams.WRAP_CONTENT));

If you are using addHeaderView(), you can't delete your header after that.
So, don't use addHeaderView(). Rather, create your own adapter that
blends your main roster of Views with your header. While my
MergeAdapter will not handle your specific case, you can use it to see
the concept of blending multiple row sources:
https://github.com/commonsguy/cwac-merge

I encountered this problem in a slightly disguised scenario: the ListView I was dealing with came from PreferenceFragment, and the header represents a PreferenceCategory. So, my freedom of setting up the ListView was severely limited. But there were two approaches (partly inspired by other answers on this page). One was to add a custom layout to my PreferenceCategory (using a class that extends android.preference.PreferenceCategory, see Custom PreferenceCategory Headings). But I found an easier workaround: for the first Preference in this PreferenceCategory, I override onCreateView():
#Override public View onCreateView(ViewGroup parent) {
parent.setTop(-parent.getChildAt(0).getTop());
return super.onCreateView(parent);
}