Develop Reference

Improve spacing between recycleView items

I have an activity with recycleView this is what I should show in design
I use this code to show it
val arr:ArrayList<string> = arrayListOf("English","Intermediate","English","English","arr","UICollectionViewFlowLayoutFlowFlowFlow","English","UICollectionViewDelegate","English","Intermediate","UIViewController","viewDidLoad","Intermediate","String","Intermediate","arr","Intermediate","UIKit","Intermediate","English","columnLayout","English","languageLabel")
recyclerView.setLayoutDirection(View.LAYOUT_DIRECTION_RTL)
recyclerView.layoutManager = GridLayoutManager(this, 3)
adaAdapter = CustomAdapter(this, arr)
recyclerView.adapter = adaAdapter
With this adapter
class CustomAdapter(val context: DreamsActivity, val items: ArrayList<String>) : RecyclerView.Adapter<CustomAdapter.ViewHolderProductList>() {
// holds this device's screen width,
private var screenWidth = 0
override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): ViewHolderProductList {
val displayMetrics = DisplayMetrics()
context.windowManager.getDefaultDisplay().getMetrics(displayMetrics)
screenWidth = displayMetrics.widthPixels
val layoutInflater = LayoutInflater.from(parent.context)
val cellForRow = layoutInflater.inflate(R.layout.dreams_collection,parent, false)
val devicewidth: Int = (displayMetrics.widthPixels / 3) - 10
val params = cellForRow.getLayoutParams() as GridLayoutManager.LayoutParams
params.width = devicewidth
cellForRow.setLayoutParams(params)
return ViewHolderProductList(cellForRow)
}
override fun getItemCount(): Int {
return items.size
}
override fun onBindViewHolder(holder: ViewHolderProductList, position: Int) {
val item = items[position]
holder.typeTv.text = item
}
inner class ViewHolderProductList(itemView: View) : RecyclerView.ViewHolder(itemView) {
var typeTv: TextView = itemView.findViewById(R.id.typeTv)
var mainL: ConstraintLayout = itemView.findViewById(R.id.mainL)
}
}
With this XML
<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".MainActivity">
<RecyclerView
android:id="#+id/recyclerView"
android:layout_width="0dp"
android:layout_height="0dp"
android:layout_marginStart="10dp"
android:layout_marginTop="20dp"
android:layout_marginEnd="10dp"
android:layout_marginBottom="15dp"
android:background="#FFFFFF"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent" />
</androidx.constraintlayout.widget.ConstraintLayout>
And Item layout
<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:id="#+id/mainL"
android:layout_width="60dp"
android:padding="10dp"
android:layout_height="wrap_content">
<androidx.constraintlayout.widget.ConstraintLayout
android:layout_width="match_parent"
android:layout_height="match_parent">
<TextView
android:id="#+id/typeTv"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginStart="5dp"
android:layout_marginTop="5dp"
android:layout_marginEnd="5dp"
android:layout_marginBottom="5dp"
android:text="TextView"
android:textSize="14sp"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent" />
</androidx.constraintlayout.widget.ConstraintLayout>
</androidx.constraintlayout.widget.ConstraintLayout>
But I got this
And don't know how to do it as I need the number of items to be dynamic according to the text length but the GridLayoutManager only sets the number of columns static.
Any help is greatly appreciated

The desired layout tends to be Chips rather than a RecyclerView
Here is a demo:
Material app gradle dependency: implementation 'com.google.android.material:material:1.4.0'
Layout:
<com.google.android.material.chip.ChipGroup xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
android:id="#+id/my_chip_group"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:padding="8dp"
app:chipSpacing="16dp"
app:chipSpacingHorizontal="4dp"
app:chipSpacingVertical="4dp" />
Adding chips:
val arr =
arrayListOf(
"English",
"Intermediate",
"English",
"English",
"arr",
"UICollectionViewFlowLayoutFlowFlowFlow",
"English",
"UICollectionViewDelegate",
"English",
"Intermediate",
"UIViewController",
"viewDidLoad",
"Intermediate",
"String",
"Intermediate",
"arr",
"Intermediate",
"UIKit",
"Intermediate",
"English",
"columnLayout",
"English",
"languageLabel"
)
fun addChips(context: Context) {
val chipGroup = findViewById<ChipGroup>(R.id.my_chip_group)
for (i in 0 until arr.size) {
val chip = Chip(context)
chip.layoutParams = FrameLayout.LayoutParams(WRAP_CONTENT, WRAP_CONTENT)
chip.text = arr[i]
chipGroup.addView(chip)
}
}

What you're asking for is something with the visual look of a Chip from Material Components. While the documentation for Chips suggests putting them in a ChipGroup, this loses the benefit of recycling views if you have more than enough to cover the screen. On the other hand, if they need to behave like a RadioGroup, where you can select only one to be toggled at a time, then ChipGroup would be easier to use.
To do this with RecylerView, you can change your item view layouts to use a Chip instead of a TextView. Set the item's layout width to wrapContent. Then use Google's Flexbox Layout library to get the layout with variable length items.
In Gradle dependencies: implementation 'com.google.android.flexbox:flexbox:3.0.0'
In your activity:
recyclerView.layoutManager = FlexboxLayoutManager(this)
.apply { flexDirection = FlexDirection.ROW }
Result:
There's a related question here that is helpful.

Different width of each horizontal RecyclerViews items

I get a problem with my horizontal RecyclerView. I need to create RecyclerView with different width of each item. I use wrap_content for this:
<?xml version="1.0" encoding="utf-8"?>
<androidx.cardview.widget.CardView
android:id="#+id/recyclerItemLayout"
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
android:orientation="horizontal"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
app:cardPreventCornerOverlap="false"
app:cardCornerRadius="#dimen/_10sdp"
android:layout_marginStart="5dp"
android:layout_marginEnd="5dp"
app:cardElevation="0dp"
app:cardBackgroundColor="#android:color/darker_gray"
android:layout_marginTop="10dp"
android:layout_marginBottom="10dp">
<TextView
android:id="#+id/recyclerItemText"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_gravity="center"
android:gravity="center"
android:textSize="#dimen/_17sdp"
android:text="test"
android:textColor="#color/colorKeyboardRecyclerViewItemText"
android:layout_marginStart="5dp"
android:layout_marginEnd="5dp"
android:layout_marginTop="7dp"
android:layout_marginBottom="7dp"/>
</androidx.cardview.widget.CardView>
But when I scroll recyclerview and get to the first element I got this:
I think it is because the adapter redraws items every time. Here is code of my adapter:
class KeyboardAdapter(private val fontsNames: FontsData, private val fontButtonCallback: (Int) -> Unit): RecyclerView.Adapter<KeyboardAdapter.ViewHolder>() {
override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): ViewHolder {
val v = LayoutInflater.from(parent.context).inflate(R.layout.keyboard_recyclerview_item, parent, false)
return ViewHolder(v)
}
override fun getItemCount(): Int {
return fontsNames.fontsArrayEn.count()
}
override fun onBindViewHolder(holder: ViewHolder, position: Int) {
holder.itemText.text = fontsNames.fontsArrayEn[position].name
val selectedColor = holder.itemLayout.context.resources.getColor(R.color.colorKeyboardRecyclerViewSelectedItem)
val backgroundColor = holder.itemLayout.context.resources.getColor(android.R.color.transparent)
holder.itemLayout.setOnClickListener{
fontButtonCallback(position)
changeIsSelectedState(position)
fontsNames.fontsArrayEn[position].isSelected = true
notifyDataSetChanged()
}
/* holder.itemLayout.post{ val itemHeight = holder.itemLayout.height.toFloat()
val itemRadius = itemHeight /2.5
holder.itemLayout.radius = Utils().intToDp(holder.itemLayout.context, itemRadius.toFloat())} */
if (fontsNames.fontsArrayEn[position].isSelected)
holder.itemLayout.setCardBackgroundColor(selectedColor)
else
holder.itemLayout.setCardBackgroundColor(backgroundColor)
}
class ViewHolder(itemView: View): RecyclerView.ViewHolder(itemView){
val itemLayout = itemView.findViewById<CardView>(R.id.recyclerItemLayout)!!
val itemText = itemView.findViewById<TextView>(R.id.recyclerItemText)!!
}
private fun changeIsSelectedState(position: Int){
for (i in 0 until fontsNames.fontsArrayEn.count()){
fontsNames.fontsArrayEn[i].isSelected = i == position
}
}
}
And i have one more question. How I can set cardCornerRadius dynamically depends of item height ?
Thanks in advance!

The TextView inside the card is the problem.
The text view is match_parent
android:layout_width="match_parent"
android:layout_height="match_parent"
But the parent is wrap_content.
Change the TextView to wrap_content and then every word is gonna be the size of the TextView and the CardView will have the size of the child.

Recyclerview view not populating

I'm a Kotlin newbie learning how to create simple recyclerview apps. My code is supposed to list the integers 1..10 in vertically stacked cells. However, it only lists the first item. I've consulted several tutorials and reviewed my code several times(after long breaks), but I can't see anything wrong in my code.
I got the bright idea early today to print Log statements. Examining them, I note that my onBindViewHolder function is only called once. What blunder am I making?
Here is my log output:
D/QuoteAdapter: value is: 1
D/QuoteAdapter: index is: 0
D/QuoteAdapter: Size is: 10
my activity:
class MainActivity : AppCompatActivity() {
lateinit var mRecyclerView: RecyclerView
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_main)
mRecyclerView = findViewById(R.id.recyclerView)
mRecyclerView.layoutManager = LinearLayoutManager(this)
mRecyclerView.adapter = QuoteAdapter()
//mRecyclerView.setHasFixedSize(true)
}
}
my adapter:
class QuoteAdapter : RecyclerView.Adapter<QuoteViewHolder>() {
private val listOfInts = intArrayOf(1, 2, 3, 4, 5, 6, 7, 8, 9, 10)
private val TAG = "QuoteAdapter"
override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): QuoteViewHolder {
val view = LayoutInflater.from(parent.context)
.inflate(R.layout.recyclerview_item_row, parent, false)
return QuoteViewHolder(view)
}
override fun getItemCount(): Int {
Log.d(TAG, "Size is: ${listOfInts.size.toString()}")
return listOfInts.size
}
override fun onBindViewHolder(holder: QuoteViewHolder, position: Int) {
val item = listOfInts[position]
Log.d(TAG, "value is: ${item.toString()}")
Log.d(TAG, "index is: ${position.toString()}")
holder.listTitle.text = item.toString()
}
}
my viewholder:
class QuoteViewHolder(itemView: View) : RecyclerView.ViewHolder(itemView) {
val listTitle = itemView.findViewById(R.id.itemString) as TextView
}
my layout:
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical" android:layout_width="match_parent"
android:layout_height="match_parent">
<TextView
android:id="#+id/itemString"
android:layout_width="match_parent"
android:layout_height="wrap_content" />
</LinearLayout>
my main layout is shown below:
<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".MainActivity">
<androidx.recyclerview.widget.RecyclerView
android:id="#+id/recyclerView"
android:layout_width="0dp"
android:layout_height="0dp"
android:layout_marginStart="8dp"
android:layout_marginLeft="8dp"
android:layout_marginTop="8dp"
android:layout_marginEnd="8dp"
android:layout_marginRight="8dp"
android:layout_marginBottom="8dp"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent" />
</androidx.constraintlayout.widget.ConstraintLayout>

In your "my layout" try this:
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical" android:layout_width="match_parent"
android:layout_height="wrap_content">
<TextView
android:id="#+id/itemString"
android:layout_width="match_parent"
android:layout_height="wrap_content" />
</LinearLayout>
Notice layout_height of LinearLayout has changed to wrap_content
Also doubt you need the android:orientation="vertical" on your ViewHolders item xml unless you will add more than just 1 TextView in the future.

Like Zain says, you can just use a TextView on its own in a layout file, which will also fix the problem (so long as its height is wrap_content!)
There are actually a few included with Android - type android.R.layout. and you'll see a few things, like simple_list_item_1 which is just a styled TextView (you can ctrl+click the reference or whatever to look at the file). Can be nice if you just want to make a quick thing!
The ID of the TextView in android.R.layout.simple_list_item_1 is #android:id/text1 - note the android prefix, because its part of the android resources, not your app's. Which means you have to reference the ID in the same way as the layout, with android at the front: android.R.id.text1

You can get rid of the LinearLayout in the list item layout, and only keep the TextView.
So, replace your list item layout with:
<TextView xmlns:android="http://schemas.android.com/apk/res/android"
android:id="#+id/itemString"
android:layout_width="match_parent"
android:layout_height="wrap_content" />

RecyclerView with horizontal GridLayoutManager adjusts its height to largest row

I want to use RecyclerView with GridLayoutManager to achieve something like that:
Here is GridLayoutManager with horizontal orientation and 2 rows. What's important for me here is that RecyclerView is set as wrap_content.
So I tried to achieve my goal with such code:
MainActivity.kt
class MainActivity : AppCompatActivity() {
private val adapter = Adapter()
private val layoutManager = GridLayoutManager(this, 2, RecyclerView.HORIZONTAL, false)
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_main)
recyclerView.adapter = adapter
recyclerView.layoutManager = layoutManager
adapter.submitList(listOf(Unit, Unit, Unit, Unit))
}
}
Adapter.kt
class Adapter : ListAdapter<Any, ItemHolder>(DiffCallback()) {
override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): ItemHolder {
val itemView = LayoutInflater.from(parent.context).inflate(viewType, parent, false)
return ItemHolder(itemView)
}
override fun onBindViewHolder(holder: ItemHolder, position: Int) {
}
override fun getItemViewType(position: Int): Int {
return when {
position % 2 == 0 -> R.layout.item_small
else -> R.layout.item_normal
}
}
class DiffCallback : DiffUtil.ItemCallback<Any>() {
override fun areItemsTheSame(oldItem: Any, newItem: Any) = false
override fun areContentsTheSame(oldItem: Any, newItem: Any) = false
}
class ItemHolder(itemView: View) : RecyclerView.ViewHolder(itemView)
}
activity_main.xml
<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".MainActivity">
<androidx.recyclerview.widget.RecyclerView
android:id="#+id/recyclerView"
android:layout_width="0dp"
android:layout_height="wrap_content"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent" />
</androidx.constraintlayout.widget.ConstraintLayout>
item_normal.xml
<?xml version="1.0" encoding="utf-8"?>
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="100dp"
android:layout_height="100dp"
android:layout_margin="8dp"
android:background="#color/colorAccent" />
item_small.xml
<?xml version="1.0" encoding="utf-8"?>
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="100dp"
android:layout_height="50dp"
android:layout_margin="8dp"
android:background="#color/colorAccent" />
Unfortunately as the result, each row stretches to the largest row in grid:
The question is how can I remove the spacing between first row and second row? Keep in mind that I have to have scrollable horizontal grid that its height depends on its content. And items have to have fixed size.

Assuming you know the ratios between heights of individual rows, you can try to use SpanSizeLookup to adjust height of each row. In your simple case, the smaller item (50dp) will take one row (span size 1) while the larger item (100dp) will take two rows (span size 2) so the whole grid overall will contain 3 rows.
Of course, for a more complex row configuration, the ratios might get a little more complicated: Say I wanted rows of heights 32dp/48dp/64dp, then the height ratios are 32/144, 48/144 and 64/144, which we can simplify to 2/9, 3/9, 4/9, getting 9 rows in total, with span sizes 2, 3, and 4 for individual items. In extreme cases, this can result in large number of rows (when the fractions cannot be simplified), but assuming you are using some type of grid (x8, x10, etc.) and the items are reasonably sized, it should still be manageable.
Anyway, in your case, the code would be this:
val layoutManager = GridLayoutManager(this, 3, RecyclerView.HORIZONTAL, false)
layoutManager.spanSizeLookup = object : GridLayoutManager.SpanSizeLookup() {
override fun getSpanSize(position: Int) = when (position % 2) {
0 -> 1 // 50dp item
else -> 2 // 100dp item
}
}
Given more rows, the when statement is going to get more complex, but if you already have the adapter at hand, you can use getItemViewType to differentiate individual rows in the when statement more easily.
If the number of item types is large or changes often (for example different item types on different screens), you can of course also implement the logic above in code, assuming you have access to the heights of the individual item types. Simply sum the heights to obtain the denominator and then find greatest common divisor of all heights and the sum to find the "simplification factor".

I think GridLayoutManager by default constraints the child views to be exactly same sizes.
I adjust the code to use a LinearLayoutManager, and the view for ViewHolder is to wrap two types views into a RelativeLayout.
See some code below:
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="wrap_content"
android:layout_height="wrap_content">
<View
android:id="#+id/top"
android:layout_width="100dp"
android:layout_height="50dp"
android:layout_margin="8dp"
android:layout_alignParentTop="true"
android:background="#color/colorAccent" />
<View
android:id="#+id/bottom"
android:layout_width="100dp"
android:layout_height="100dp"
android:layout_margin="8dp"
android:layout_below="#+id/top"
android:background="#color/colorAccent" />
</RelativeLayout>
RecyclerAdapter:
View view = LayoutInflater.from(viewGroup.getContext()).inflate(
R.layout.item_normal,
viewGroup,
false
);
ViewHolder viewHolder = new ViewHolder(view);
return viewHolder;
And set LinearLayoutManager:
LinearLayoutManager layoutManager = new LinearLayoutManager(this, RecyclerView.HORIZONTAL, false);
recyclerView.setLayoutManager(layoutManager);

Try to use a StaggeredGridLayoutManager to have different heights. Replace your GridLayoutManager with the below StaggeredGridLayoutManager
StaggeredGridLayoutManager layoutManager = new StaggeredGridLayoutManager(2, StaggeredGridLayoutManager.VERTICAL);

Recyclerview only showing first value

i am having an issue with my gson parsing. I have a nested gson and i would like get the value of "name" under attributes. The problem is my recyclerview is only showing the first value(which is bill 1) and not bill 2 or bill 3. here is my code
// MainActivity.kt
recycler_view.layoutManager = LinearLayoutManager(requireContext())
recycler_view.addItemDecoration(LineItemDecorator(requireContext()))
val bill = GsonBuilder().create().fromJson(jsonString, Bills::class.java)
val nameList: List<Bill> = Arrays.asList(bill)
val adapter = BillsRecyclerAdapter(nameList)
recycler_view.adapter = adapter
adapter.notifyDataSetChanged()
// Bills.kt
data class Bills(
val data: ArrayList<Data>,
val meta: Meta,
val links: Links
)
// BillsRecyclerAdapter.kt
class BillsRecyclerAdapter(private val items: List<Bill>):
RecyclerView.Adapter<BillsRecyclerAdapter.BillsHolder>() {
override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): BillsHolder {
return BillsHolder(parent.inflate(R.layout.bills_list_item))
}
override fun onBindViewHolder(holder: BillsHolder, position: Int) {
holder.billName.text = items[position].data[position].attributes.name
}
override fun getItemCount() = items.size
class BillsHolder(view: View): RecyclerView.ViewHolder(view) {
val billName: TextView = view.billName
val billAmount: TextView = view.billAmount
}
}
<!-- recyclerview.xml -->
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical"
android:layout_width="match_parent"
android:layout_height="match_parent">
<androidx.recyclerview.widget.RecyclerView
android:id="#+id/recycler_view"
android:layout_marginTop="#dimen/materialize_toolbar"
android:layout_width="match_parent"
android:layout_height="match_parent" />
</LinearLayout>
<!-- bill_list_item.xml-->
<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
android:orientation="vertical"
android:layout_width="match_parent"
android:layout_height="match_parent">
<TextView
android:id="#+id/billName"
android:textSize="20sp"
android:layout_marginStart="8dp"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
app:layout_constraintStart_toStartOf="parent"/>
<TextView
android:id="#+id/billAmount"
android:textSize="20sp"
android:layout_marginEnd="8dp"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
app:layout_constraintEnd_toEndOf="parent"/>
</androidx.constraintlayout.widget.ConstraintLayout>
here is my json string. https://pastebin.com/iEqhmB35
thanks for any help provided

Check the following
Check your items.size if it really is not zero,
Also check your bills_list_item.xml try to set the root parent's height to wrap_content
Also check if you have this on you recyclerview
recyclerView.setHasFixedSize(true);
recyclerView.setItemAnimator(new DefaultItemAnimator());
recyclerView.setLayoutManager(new LinearLayoutManager(getContext()));
What's important there is the layout manager
If it doesn't help, can you share your Bills.java class, there might be something wrong with the serialization of JSON raw data.
Hope this helps.
Cheers