RecyclerView's GridLayoutManger allows to lay out items of recyclerView in grid format , Lets see example .
Add RecyclerView to your layout
Create XML Layout activity_main.xml , this will be set as content view for launcher Activity (MainActivity.kt) and add RecyclerView to your layout file
file : activity_main.xml
<?xml version="1.0" encoding="utf-8"?>
<androidx.recyclerview.widget.RecyclerView
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:id="@+id/recyclerView"/>
Data Class
file : Model.kt
package com.tutorialsbuzz.recyclerview
data class Model(val name: String, val version: String) {}
To Load Data Into RecyclerView , We will read JSON File Kept Inside Asset folder and map it to above defined data class .
file : main\assets\android_version.json
[
{
"name": "Cupcake",
"version": "Android 1.5"
},
{
"name": "Donut",
"version": "Android 1.6"
},
{
"name": "Eclairs",
"version": "Android 2.0-2.1"
},
{
"name": "Froyo",
"version": "Android 2.2-2.3"
},
{
"name": "Gingerbread",
"version": "Android 2.3-2.3.7"
},
{
"name": "Honeycomb",
"version": "Android 3.0-3.2.6"
},
{
"name": "Icecream",
"version": "Android 4.0-4.0.4"
},
{
"name": "Jellybean",
"version": "Android 4.1-4.3.1"
},
{
"name": "Kitkat",
"version": "Android 4.4-4.4.4"
},
{
"name": "Lolipop",
"version": "Android 5.0-5.1.1"
},
{
"name": "Marshmallow",
"version": "Android 6.0-6.0.1"
},
{
"name": "Nougat",
"version": "Android 7.0-7.1.2"
},
{
"name": "Oreo",
"version": "Android 8.0-8.1"
},
{
"name": "Pie",
"version": "Android 9.0"
}
]
Image Resource
Name field from json matches to respective png file name kept inside drawable .
Folder : app\src\main\res\drawable
Adapter and ViewHolder For RecyclerView .
1. Create Grid Cell Layout
Create XML Layout file in res/layout and name it row_item.xml .
file : row_item.xml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:padding="18dp"
android:gravity="center"
android:orientation="vertical">
<com.tutorialsbuzz.recyclerviewgrid.CirleImageView
android:layout_width="60dp"
android:layout_height="60dp"
app:civ_border_width="8dp"
app:civ_border_color="#e5e5e5"
android:id="@+id/img"
android:contentDescription="@string/app_name"/>
<TextView
android:id="@+id/txt"
android:textSize="14sp"
android:text="Title"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:singleLine="true"
android:textStyle="bold"/>
<TextView
android:id="@+id/sub_txt"
android:textSize="14sp"
android:text="Title"
android:visibility="gone"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:textStyle="italic"/>
</LinearLayout>
2. Adapter class
Create a Adapter That RecyclerView Can Use ,Create a class CustomAdapter extend it to RecyclerView.Adapter .
RecyclerView.Adapter has three abstract methods that we must override .
- onCreateViewHolder() : Inside this method we specify the layout that each item of the RecyclerView should use .onCreateViewHolder has return type of RecyclerView.ViewHolder which represent each row of recyclerView . Using Inflator get the view of above defined row_item and pass it to viewholder constructor and then return.
- onBindViewHolder() : Inside this method data will be displayed at the specified position .
- getItemCount() : Returns the total number of items in the data set held by the adapter.
3. ViewHolder
Create Inner class ViewHolder extend it to RecyclerView.ViewHolder , add bind function which takes above defined model data class object
Create Inner class ViewHolder extend it to RecyclerView.ViewHolder , add bind function which takes above defined model data class object
file : CustomAdapter.kt
package com.tutorialsbuzz.recyclerview
import android.content.Context
import android.view.LayoutInflater
import android.view.View
import android.view.ViewGroup
import androidx.recyclerview.widget.RecyclerView
import com.tutorialsbuzz.recyclerviewgrid.R
import kotlinx.android.synthetic.main.row_item.view.*
class CustomAdapter(val modelList: List<Model>, val context: Context) :
RecyclerView.Adapter<RecyclerView.ViewHolder>() {
override fun onBindViewHolder(holder: RecyclerView.ViewHolder, position: Int) {
(holder as ViewHolder).bind(modelList.get(position));
}
override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): RecyclerView.ViewHolder {
val layoutInflater = LayoutInflater.from(parent.context)
return ViewHolder(layoutInflater.inflate(R.layout.row_item, parent, false))
}
override fun getItemCount(): Int {
return modelList.size;
}
lateinit var mClickListener: ClickListener
fun setOnItemClickListener(aClickListener: ClickListener) {
mClickListener = aClickListener
}
interface ClickListener {
fun onClick(pos: Int, aView: View)
}
inner class ViewHolder(itemView: View) : RecyclerView.ViewHolder(itemView), View.OnClickListener {
init {
itemView.setOnClickListener(this)
}
override fun onClick(p0: View?) {
mClickListener.onClick(adapterPosition, itemView)
}
fun bind(model: Model): Unit {
itemView.txt.text = model.name
itemView.sub_txt.text = model.version
val id = context.resources.getIdentifier(model.name.toLowerCase(), "drawable", context.packageName)
itemView.img.setImageResource(id)
}
}
}
Applying GridLayoutManger To RecyclerView
GridLayoutManger is a subclass of RecyclerView.LayoutManager , This class lay out items of recyclerView in grid format .
GridLayoutManager(Context context, int spanCount)
The Above Constructor Creates Vertical GridLayoutManager and it takes two parameters
- Context: Current context, will be used to access resources.
- int: The number of columns in the grid
recyclerView.layoutManager = GridLayoutManager(this, 4)
Activity
- Override onCreate function and set the content of this MainActivity with above defined xml layout (activity_main.xml).
- Read JSON Data From Asset Folder , this will be used for binding data into RecyclerView .
- Set GridLayoutManager to RecyclerView.
- Create Instance of Adapter and set to RecyclerView .
file : MainActivity.kt
package com.tutorialsbuzz.recyclerviewgrid
import android.os.Bundle
import android.view.View
import android.widget.Toast
import androidx.appcompat.app.AppCompatActivity
import androidx.recyclerview.widget.GridLayoutManager
import com.tutorialsbuzz.recyclerview.CustomAdapter
import com.tutorialsbuzz.recyclerview.Model
import kotlinx.android.synthetic.main.activity_main.*
import org.json.JSONArray
import org.json.JSONObject
class MainActivity : AppCompatActivity() {
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_main)
val model = readFromAsset();
val adapter = CustomAdapter(model, this)
recyclerView.layoutManager = GridLayoutManager(this, 4)
recyclerView.adapter = adapter;
adapter.setOnItemClickListener(object : CustomAdapter.ClickListener {
override fun onClick(pos: Int, aView: View) {
Toast.makeText(this@MainActivity, model.get(pos).name, Toast.LENGTH_SHORT).show()
}
})
}
private fun readFromAsset(): List<Model> {
val modeList = mutableListOf<Model>()
val bufferReader = application.assets.open("android_version.json").bufferedReader()
val json_string = bufferReader.use {
it.readText()
}
val jsonArray = JSONArray(json_string);
for (i in 0..jsonArray.length() - 1) {
val jsonObject: JSONObject = jsonArray.getJSONObject(i)
val model = Model(jsonObject.getString("name"), jsonObject.getString("version"))
modeList.add(model)
}
return modeList
}
}
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