Develop Reference

How to open a "Details" Fragment onclick of Recyclerview in Kotlin

I have home fragment and I want it to go to another fragment which will show its "details", which passes the data of the clicked recyclerview item to that "details" fragment.
When I click the article it will move to detail article which passes the data.
As for the code, here's the adapter:
class ArticleAdapter(private val articleList: ArrayList<Article>) :
RecyclerView.Adapter<ArticleAdapter.MyViewHolder>() {
override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): MyViewHolder {
val binding = ItemArticleBinding.inflate(LayoutInflater.from(parent.context), parent, false)
return MyViewHolder(binding)
}
override fun onBindViewHolder(holder: MyViewHolder, position: Int) {
val data = articleList[position]
holder.bind(data)
}
class MyViewHolder(private val binding: ItemArticleBinding) :
RecyclerView.ViewHolder(binding.root) {
fun bind(data: Article) {
Glide.with(binding.root.context)
.load(data.img)
.into(binding.articleImage)
binding.articleTitle.text = data.title
binding.root.setOnClickListener {
val article = Article(
data.title,
data.img,
data.content
)
}
}
}
override fun getItemCount(): Int {
return articleList.size
}
}
Here's my detailFragment
class DetailArticleFragment : Fragment() {
private var _binding: FragmentDetailArticleBinding? = null
private val binding get() = _binding!!
override fun onCreateView(
inflater: LayoutInflater,
container: ViewGroup?,
savedInstanceState: Bundle?
): View {
_binding = FragmentDetailArticleBinding.inflate(inflater, container, false)
return binding.root
}
override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
super.onViewCreated(view, savedInstanceState)
val intent = Intent(binding.root.context, DetailArticleFragment::class.java)
val article = intent.getParcelableExtra<Article>(DETAIL_ARTICLE) as Article
Glide.with(this)
.load(article.img)
.into(_binding!!.articleImage)
_binding!!.articleTitle.text = article.title
_binding!!.articleDescription.text = article.content
}
override fun onDestroyView() {
super.onDestroyView()
_binding = null
}
companion object {
const val DETAIL_ARTICLE = "detail_article"
}
}

You need to pass click listener interface to adapter, for example:
typealias OnArticleClick = (article: Article) -> Unit
class ArticleAdapter(
private val articleList: ArrayList<Article>
) :
RecyclerView.Adapter<ArticleAdapter.MyViewHolder>() {
var onArticleClick: OnArticleClick? = null
...
binding.root.setOnClickListener {
val article = Article(
data.title,
data.img,
data.content
)
onArticleClick?.invoke(article)
}
...
}
And init onArticleClick in your home fragment with RecyclerView:
adapter.apply {
onArticleClick = {
// show details fragment
}
}

android kotlin property does not change with passed method to adapter

i have defined a val in my fragment like so
private var selectionMode: Boolean = false
and a property to change it
fun enableSelectionMode() {
selectionMode = true
}
and i passed both to Adapter and want to call enableSelectionMode after clicking on each recycler item but nothing happen
here is my fragment:
class PostsFragment : Fragment() {
private val model: PostsViewModel by activityViewModels()
private var selectionMode: Boolean = false
fun enableSelectionMode() {
selectionMode = true
}
private lateinit var recyclerView: RecyclerView
override fun onCreateView(
inflater: LayoutInflater, container: ViewGroup?,
savedInstanceState: Bundle?
): View? {
val view = inflater.inflate(R.layout.fragment_posts, container, false)
recyclerView = view.findViewById(R.id.posts_recycler)
recyclerView.layoutManager = LinearLayoutManager(view.context)
model.posts.observe(viewLifecycleOwner, { items ->
recyclerView.adapter = PostsAdapter(items, model, selectionMode,
::enableSelectionMode)
})
return view
}
}
and my adapter
class PostsAdapter(
private val posts: List<Post>,
private val model: PostsViewModel,
private val selectionMode: Boolean,
private val enableIt: () -> Unit
) :
RecyclerView.Adapter<PostsAdapter.ViewHolder>() {
companion object {
private const val TYPE_FROM = 0
private const val TYPE_TO = 1
}
inner class ViewHolder(itemView: View) : RecyclerView.ViewHolder(itemView) {
var postContent: TextView = itemView.findViewById(R.id.post_content)
var selectPostCheckBox: ImageView = itemView.findViewById(R.id.post_select_checkbox)
}
override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): ViewHolder {
val view = LayoutInflater.from(parent.context)
.inflate(
if (viewType == TYPE_TO) R.layout.to_post else R.layout.from_post,
parent,
false
)
return ViewHolder(view)
}
#SuppressLint("CheckResult")
override fun onBindViewHolder(holder: ViewHolder, position: Int) {
holder.selectPostCheckBox.visibility = if (selectionMode) View.VISIBLE else View.GONE
holder.postContent.text = selectionMode.toString()
holder.selectPostCheckBox.setImageResource(R.drawable.cursor_color)
holder.itemView.setOnClickListener() {
enableIt()
notifyDataSetChanged()
}
}
override fun getItemCount() = posts.size
override fun getItemViewType(position: Int): Int {
return posts[position].selfPost
}
}

How to create custom arrayAdapter without context attribute

For a school project, I made a custom arrayadapter with a context, resources and items attribute. Today I received feedback from my teacher and he wants me to find a solution where I don't have a Context attribute because he doesnt like that I always need to specify the context.
This is my code:
class TalentListAdapter(
var mCtx: Context,
var resources: Int,
var items: MutableList<Talent>
) : ArrayAdapter<Talent>(mCtx, resources, items) {
lateinit var mItem: Talent
override fun getView(position: Int, convertView: View?, parent: ViewGroup): View {
val layoutInflater: LayoutInflater = LayoutInflater.from(mCtx)
val view: View = layoutInflater.inflate(resources, null)
mItem = items[position]
//set name of talent
val talentTextView: TextView = view.findViewById(R.id.talentName)
talentTextView.text = mItem.toString()
return view
}
}
He wants to get rid of the mCtx: Context attribute, but I don't find a solution for it. Any suggestions?
The adapter is created like this atm:
override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
super.onViewCreated(view, savedInstanceState)
val listView: ListView = binding.talentList
// set custom adapter for talent_list
val adapter = TalentListAdapter(view.context, R.layout.talentlayout, binding.talentViewModel?.getTalents()?.value as MutableList<Talent>)
listView.adapter = adapter
}

Can you try this
class YourAdapter() : RecyclerView.Adapter<YourAdapter.ViewHolder>() {
inner class ViewHolder(val view: View) : RecyclerView.ViewHolder(view)
var Data: List<YourResponse> = emptyList()
set(value) {
field = value
notifyDataSetChanged()
}
override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): ViewHolder {
val view = LayoutInflater.from(parent.context).inflate(
R.layout.your_layout, parent, false
)
return ViewHolder(view)
}
override fun getItemCount(): Int {
return Data.size
}
override fun onBindViewHolder(holder: ViewHolder, position: Int) {
val getYourModel = Data[position]
val Binding = holder.view
Binding.yourTextView.apply{
text = getYourModel.yourField
}
.....
}
}
and pass Data from your Fragment or Activity (my example uses Retrofit2)
private var theList: List<YourResponse> = emptyList()
private val theAdapter =yourAdapter()
override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
super.onViewCreated(view, savedInstanceState)
onUpdateData()
}
private fun onUpdateData() {
...
override fun onResponse(call: Call<YourResponse>, response: Response<YourResponse>) {
val body = response.body()?.results
if (response.isSuccessful && body != null) {
onUpdateDataSuccess(body)
} else {
// Something
}
}
...
}
private fun onUpdateDataSuccess(data: List<YourResponse>) {
theList = data
theAdapter.Data = data
}
...

You only need context while inflating so you should use parent.context instead of explicit context.
Parent.Context represent the Activity/Fragment where this recycler view is implemented.

Sharing recyclerview item ID with another fragment

Currently I have a recyclerview adapter that gets data from the database and displays it in the dashboard fragment. Once the item is clicked, I want to pass the item id to the details fragment to get the correct items information on the detailed view. How can I pass this ID to the detailed fragment?
Dashboard Fragment
class DashboardFragment : Fragment() {
private lateinit var viewModel: DashboardViewModel
override fun onCreateView(inflater: LayoutInflater, container: ViewGroup?,
savedInstanceState: Bundle?): View? {
// Get a reference to the binding object and inflate the fragment views.
val binding: DashboardFragmentBinding = DataBindingUtil.inflate(
inflater, R.layout.dashboard_fragment, container, false)
val application = requireNotNull(this.activity).application
val dataSource = NumberDatabase.getInstance(application).numberDatabaseDao
val viewModelFactory = DashboardViewModelFactory(dataSource, application)
// Get a reference to the ViewModel associated with this fragment.
val dashboardViewModel =
ViewModelProviders.of(
this, viewModelFactory).get(DashboardViewModel::class.java)
// To use the View Model with data binding, you have to explicitly
// give the binding object a reference to it.
binding.dashboardViewModel = dashboardViewModel
val adapter = CounterAdapter(CounterListener { nightId ->
dashboardViewModel.onCountClicked(nightId)
})
binding.counterList.adapter = adapter
dashboardViewModel.counts.observe(viewLifecycleOwner, Observer {
it?.let {
adapter.submitList(it)
}
})
}
Adapter
class CounterAdapter (val clickListener: CounterListener): ListAdapter<Number, CounterAdapter.ViewHolder>(NightDiffCallback()) {
override fun onBindViewHolder(holder: ViewHolder, position: Int) {
holder.bind(getItem(position)!!, clickListener)
}
override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): ViewHolder {
return ViewHolder.from(parent)
}
class ViewHolder private constructor(val binding: ListItemCounterBinding) : RecyclerView.ViewHolder(binding.root){
fun bind(item: Number, clickListener: CounterListener) {
binding.night = item
binding.clickListener = clickListener
binding.executePendingBindings()
}
companion object {
fun from(parent: ViewGroup): ViewHolder {
val layoutInflater = LayoutInflater.from(parent.context)
val binding = ListItemCounterBinding.inflate(layoutInflater, parent, false)
return ViewHolder(binding)
}
}
}
}
class CounterListener(val clickListener: (nightId: Long) -> Unit) {
fun onClick(night: Number) = clickListener(night.nightId)
}

In your recyclerview
class RecipeRecyclerAdapter(
mFragmentCommunication: FragmentCommunication
) :
RecyclerView.Adapter<RecyclerView.ViewHolder>() {
private var mFragmentCommunication: FragmentCommunication? = null
init {
this.mFragmentCommunication =mFragmentCommunication
}
override fun onCreateViewHolder(parent: ViewGroup, viewType: Int):
RecyclerView.ViewHolder {
view = LayoutInflater.from(parent.context)
.inflate(
com.broadcast.recipeslistapp.R.layout.layout_recipe_list_item,
parent,
false
)
return RecipeViewHolder(view)
}
}
override fun getItemCount(): Int {
if (mRecipes.isNullOrEmpty()) {
return 0
} else {
return mRecipes!!.size
}
}
override fun onBindViewHolder(holder: RecyclerView.ViewHolder, position: Int) {
holder.itemView.setOnClickListener {
mFragmentCommunication!!.PassNightId(nightId = 1) //value of nightId
}
}
interface FragmentCommunication {
fun PassNightId(nightId: Int)
}
Fragment A from where you want to send data :
class RecipeListActivity : BaseActivity(),
RecipeRecyclerAdapter.FragmentCommunication {
private lateinit var layoutManager: LinearLayoutManager
}
private fun initRecyclerView() {
mAdapter = RecipeRecyclerAdapter( this)
val itemDecorator = VerticalSpacingItemDecorator(30);
recipe_list.addItemDecoration(itemDecorator);
recipe_list.adapter = mAdapter
layoutManager = LinearLayoutManager(this);
recipe_list.layoutManager = layoutManager
}
override fun PassNightId(nightId: Int) {
val testFragment = TestFragment()
val bundle = Bundle()
bundle.putString("nightId", "$nightId")
testFragment.arguments = bundle
supportFragmentManager.beginTransaction().replace(R.id.containerId,testFragment).commit()
}
}
Fragment B where you want to getData :
class TestFragment : Fragment()
{
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
val nightId =arguments?.getString("nightId")
}
override fun onCreateView(
inflater: LayoutInflater,
container: ViewGroup?,
savedInstanceState: Bundle?
): View? {
return inflater.inflate(R.layout.test_fragment,container,false)
}
}
This is how you can send data from on fragment to another fragment.

ViewPager2 | View.ClickListener not called

I use new android widget ViewPager2 version 1.0.0-alpha03 and when I set click listener on it method onClick() not called.
My Actvity class:
class MainActivity : AppCompatActivity() {
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_main)
supportFragmentManager.beginTransaction()
.add(R.id.fragmentContent, SecondFragment.newInstance(), SecondFragment.TAG)
.addToBackStack(SecondFragment.TAG)
.commit()
}
}
My Fragment:
class SecondFragment : Fragment() {
companion object {
val TAG = SecondFragment::class.java.canonicalName
fun newInstance(): SecondFragment = SecondFragment()
}
override fun onCreateView(
inflater: LayoutInflater,
container: ViewGroup?,
savedInstanceState: Bundle?
): View? {
return inflater.inflate(R.layout.fragment_second, container, false)
}
override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
viewPager2.setOnClickListener {
Log.d("logi", "click : ")
}
}
}
My layout xml file:
<androidx.coordinatorlayout.widget.CoordinatorLayout
xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent">
<androidx.viewpager2.widget.ViewPager2
android:id="#+id/viewPager2"
android:layout_width="match_parent"
android:layout_height="match_parent"/>
</androidx.coordinatorlayout.widget.CoordinatorLayout>
Any assumption or workaround?

I found a solution! ViewPager2 contains RecyclerView and we must work with it as RecyclerView. I created RecyclerView.Adapter and set the ClickListener on itemView into the constructor RecyclerView.ViewHolder and VOILA!!!
in Fragment:
override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
viewPager2.adapter = ViewPager2Adapter {
Log.d("logi", "clicked at : $it")
}
}
RecyclerView adapter:
class ViewPager2Adapter(private val itemClickListener: (Int) -> (Unit)) :
RecyclerView.Adapter<RecyclerView.ViewHolder>() {
val items = mutableListOf<Any>()
override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): RecyclerView.ViewHolder =
ItemViewHolder(LayoutInflater.from(parent.context).inflate(R.layout.item, parent, false))
override fun getItemCount(): Int = items.size
override fun onBindViewHolder(holder: RecyclerView.ViewHolder, position: Int) {
// bind your items
}
private inner class ItemViewHolder(itemView: View): RecyclerView.ViewHolder(itemView) {
init {
itemView.setOnClickListener {
Log.d("logi", "Click!") // WORKS!!!
itemClickListener(adapterPosition)
}
}
}
}

Another approach can be like below:
class MyAdapter(
private val items: List<Any>,
private val onItemClickListener: OnItemClickListener
) : RecyclerView.Adapter<MyAdapter.MyViewHolder>() {
override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): MyViewHolder {
val itemView = parent.inflate(R.layout.item_details_view_pager)
return MyViewHolder(itemView)
}
override fun getItemCount(): Int = items.size
override fun onBindViewHolder(holder: MyViewHolder, position: Int) {
holder.imageView.apply {
setOnClickListener {
onItemClickListener.onItemClick(position)
}
...
}
}
inner class MyViewHolder(itemView: View) : RecyclerView.ViewHolder(itemView) {
val imageView: ImageView = itemView.findViewById(R.id.some_image_view)
}
}
The constructor parameter onItemClickListener could be a lambda as well, but it's a simple interface for me:
interface OnItemClickListener {
fun onItemClick(position: Int)
}