RecyclerView: ItemClick

<?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/list"

android:layout_width="match_parent"

android:layout_height="match_parent"

app:layout_constraintBottom_toBottomOf="parent"

app:layout_constraintEnd_toEndOf="parent"

app:layout_constraintHorizontal_bias="0.5"

app:layout_constraintStart_toStartOf="parent"

app:layout_constraintTop_toTopOf="parent"

tools:listitem="@layout/list_item" />

</androidx.constraintlayout.widget.ConstraintLayout>

<?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="wrap_content">

<TextView

android:id="@+id/name"

android:layout_width="0dp"

android:layout_height="wrap_content"

android:layout_marginStart="8dp"

android:layout_marginTop="8dp"

android:layout_marginEnd="8dp"

android:layout_marginBottom="8dp"

android:textAppearance="@style/TextAppearance.AppCompat.Large"

android:textSize="30sp"

app:layout_constraintBottom_toBottomOf="parent"

app:layout_constraintEnd_toStartOf="@+id/is_married"

app:layout_constraintStart_toStartOf="parent"

app:layout_constraintTop_toTopOf="parent"

tools:text="Name" />

<TextView

android:id="@+id/age"

android:layout_width="wrap_content"

android:layout_height="wrap_content"

android:layout_marginEnd="8dp"

app:layout_constraintBottom_toTopOf="@+id/is_married"

app:layout_constraintEnd_toEndOf="parent"

app:layout_constraintTop_toTopOf="@+id/name"

tools:text="age" />

<TextView

android:id="@+id/is_married"

android:layout_width="wrap_content"

android:layout_height="wrap_content"

app:layout_constraintBottom_toBottomOf="@+id/name"

app:layout_constraintEnd_toEndOf="@+id/age"

app:layout_constraintTop_toBottomOf="@+id/age"

tools:text="isMarried" />

</androidx.constraintlayout.widget.ConstraintLayout>

<resources>

……

<string name="married">Married</string>

<string name="un_married">Un married</string>

</resources>

package domain.recyclerviewsample

import androidx.appcompat.app.AppCompatActivity

import android.os.Bundle

import android.widget.Toast

import androidx.recyclerview.widget.LinearLayoutManager

import red.mercy.recyclerviewsample.databinding.ActivityMainBinding

class MainActivity : AppCompatActivity() {

private lateinit var binding: ActivityMainBinding

// Item がクリックされた時に実行する処理(interface) を実装する

private val onItemClick = object : MyAdapter.Callback {

override fun onItemClick(person: Person) {

Toast.makeText(applicationContext, person.toString(), Toast.LENGTH_SHORT).show()

}

}

override fun onCreate(savedInstanceState: Bundle?) {

super.onCreate(savedInstanceState)

binding = ActivityMainBinding.inflate(layoutInflater)

setContentView(binding.root)

val persons = arrayListOf(

Person("Bob", 23, false),

Person("John", 25, true),

Person("Nancy", 22, true),

Person("Maria", 20, false),

Person("Mirror", 28, false),

Person("David", 27, true),

Person("Ada", 26, true)

)

val viewManager = LinearLayoutManager(this)

// 実装した interface を Adapter のコンストラクタ引数として渡す

val myAdapter = MyAdapter(this, persons, onItemClick)

binding.list.apply {

layoutManager = viewManager

adapter = myAdapter

}

}

}

package domain.recyclerviewsample

import android.content.Context

import android.view.LayoutInflater

import android.view.ViewGroup

import androidx.recyclerview.widget.RecyclerView

import red.mercy.recyclerviewsample.databinding.ListItemBinding

class MyAdapter(

private val context: Context,

private val persons: ArrayList<Person>,

private val callback: Callback

) : RecyclerView.Adapter<MyAdapter.ViewHolder>() {

// Item がクリックされた時に呼び出す処理を

// interface として定義

interface Callback {

fun onItemClick(person: Person)

}

private val inflater = LayoutInflater.from(context)

override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): ViewHolder =

ViewHolder(context, ListItemBinding.inflate(inflater, parent, false), callback)

override fun onBindViewHolder(holder: ViewHolder, position: Int) = holder.bind(persons[position])

override fun getItemCount(): Int = persons.size

class ViewHolder(

private val context: Context,

private val binding: ListItemBinding,

private val callback: Callback

) : RecyclerView.ViewHolder(binding.root) {

fun bind(person: Person) {

binding.run {

// ItemView の OnClickListener で、interface のメソッドを呼び出す

root.setOnClickListener {

callback.onItemClick(person)

}

name.text = person.name

age.text = person.age.toString()

isMarried.text = context.getString(if (person.isMarried) R.string.married else R.string.un_married)

}

}

}

}

package domain.recyclerviewsample

import java.io.Serializable

data class Person(

val name: String,

val age: Int,

val isMarried: Boolean = false

) : Serializable {

override fun toString(): String =

"name: $name, age: $age, ${if (isMarried) "Married" else "Un married"}"

}