MainActivity.kt
package com.cfsuman.kotlintutorials
import android.os.Bundle
import android.widget.Button
import androidx.appcompat.app.AppCompatActivity
import androidx.recyclerview.widget.LinearLayoutManager
import androidx.recyclerview.widget.RecyclerView
class MainActivity : AppCompatActivity() {
private lateinit var context:MainActivity
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_main)
// Get the context
context = this;
// Get the widgets reference from XML layout
val button = findViewById<Button>(R.id.button)
val recyclerView = findViewById<RecyclerView>(R.id.recyclerView)
// initialize a mutable list of animals
val animals = mutableListOf(
"Squirrel", "Mouse", "Chameleon",
"Deer", "Raccoon", "Antelope",
"Beaver", "Weasel", "Hedgehog",
"Lynx", "Groundhog", "Anteater",
"Wombat"
)
// initialize an instance of linear layout manager
LinearLayoutManager(
context, // context
RecyclerView.VERTICAL, // orientation
false // reverse layout
).apply {
// specify the layout manager for recycler view
recyclerView.layoutManager = this
}
// finally, data bind the recycler view with adapter
val adapter = RecyclerViewAdapter(animals).apply {
recyclerView.adapter = this
}
button.setOnClickListener {
// schedules the layout animation to be played
// after the next layout pass of this view group
recyclerView.scheduleLayoutAnimation()
// refresh the recycler view
adapter.notifyDataSetChanged()
//adapter.notifyItemChanged(0)
}
}
}
RecyclerViewAdapter.kt
package com.cfsuman.kotlintutorials
import android.view.LayoutInflater
import android.view.View
import android.view.ViewGroup
import android.widget.TextView
import androidx.recyclerview.widget.RecyclerView
class RecyclerViewAdapter(private val animals: MutableList<String>)
: RecyclerView.Adapter<RecyclerViewAdapter.ViewHolder>() {
override fun onCreateViewHolder(
parent: ViewGroup, viewType: Int): ViewHolder {
// inflate the custom view from xml layout file
val view: View = LayoutInflater.from(parent.context)
.inflate(R.layout.custom_view,parent,false)
// return the view holder
return ViewHolder(view)
}
override fun onBindViewHolder(holder: ViewHolder, position: Int) {
// display the current animal
holder.animal.text = "${position+1}. ${animals[position]}"
}
override fun getItemCount(): Int {
// number of items in the data set held by the adapter
return animals.size
}
class ViewHolder(itemView: View)
: RecyclerView.ViewHolder(itemView){
val animal: TextView = itemView.findViewById(R.id.tvAnimal)
}
// this two methods useful for avoiding duplicate item
override fun getItemId(position: Int): Long {
return position.toLong()
}
override fun getItemViewType(position: Int): Int {
return position
}
}
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"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:id="@+id/rootLayout"
android:background="#DCDCDC"
android:padding="8dp">
<Button
android:id="@+id/button"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginStart="8dp"
android:text="Refresh"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent" />
<androidx.recyclerview.widget.RecyclerView
android:id="@+id/recyclerView"
android:layout_width="0dp"
android:layout_height="0dp"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="@+id/button"
android:layoutAnimation="@anim/recyclerview_layout_animation" />
</androidx.constraintlayout.widget.ConstraintLayout>
custom_view.xml
<?xml version="1.0" encoding="utf-8"?>
<androidx.cardview.widget.CardView
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
android:id="@+id/cardView"
android:layout_width="match_parent"
android:layout_height="wrap_content"
app:cardBackgroundColor="#F8F8F8"
app:cardCornerRadius="8dp"
app:cardElevation="4dp"
app:cardMaxElevation="6dp"
app:contentPadding="24dp"
android:layout_margin="4dp">
<androidx.constraintlayout.widget.ConstraintLayout
android:layout_width="match_parent"
android:layout_height="wrap_content">
<TextView
android:id="@+id/tvAnimal"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:fontFamily="sans-serif"
android:textSize="24sp"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent" />
</androidx.constraintlayout.widget.ConstraintLayout>
</androidx.cardview.widget.CardView>
res/anim/recyclerview_item_animation.xml
<?xml version="1.0" encoding="utf-8"?>
<!-- recycler view item fall down animation -->
<set
xmlns:android="http://schemas.android.com/apk/res/android"
android:duration="500">
<translate
android:fromYDelta="-20%"
android:toYDelta="0"
android:interpolator="@android:anim/decelerate_interpolator" />
<alpha
android:fromAlpha="0"
android:toAlpha="1"
android:interpolator="@android:anim/decelerate_interpolator" />
<scale
android:fromXScale="105%"
android:fromYScale="105%"
android:toXScale="100%"
android:toYScale="100%"
android:pivotX="50%"
android:pivotY="50%"
android:interpolator="@android:anim/decelerate_interpolator" />
</set>
res/anim/recyclerview_layout_animation.xml
<?xml version="1.0" encoding="utf-8"?>
<!-- important: tweak the delay percentage
to slow down or speed up animation -->
<layoutAnimation
xmlns:android="http://schemas.android.com/apk/res/android"
android:animation="@anim/recyclerview_item_animation"
android:animationOrder="normal"
android:delay="50%" />
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