[Android] RecyclerView の基本的な設定

Android7

RecyclerView は、ListView をさらに進化させて柔軟にしたものだそうです。
cellをドラッグ&ドロップさせたり追加・消去などに強みを発揮するようですが、ここでは簡単な基本設定を試してみます。
　

Android Studio 2.2.2
Android 7.1.1

RecyclerView

　
わかりやすい説明がGoogle Developerのリストとカードの作成にあります。ここではそれにあるサンプルコードを元にして実際に動かしてみたいと思います。

　

　
基本的にはListViewの進化形なので、ListViewがわかっていることが前提です。

LayoutManagerはアイテムの位置調整を行い、ビューの再利用（Recycle）する機能をもっているそうですが、ListViewでもconvertViewを駆使すればできていた事でしたが、あえて記述しなくても良くなったということでしょうか。
　
レイアウトのサンプルコードをLinearLayoutに入れました。
activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/activity_main"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    tools:context=".MainActivity">

    <!-- A RecyclerView with some commonly used attributes -->
    <android.support.v7.widget.RecyclerView
        android:id="@+id/my_recycler_view"
        android:scrollbars="vertical"
        android:layout_width="match_parent"
        android:layout_height="match_parent"/>

</LinearLayout>

<?xml version="1.0" encoding="utf-8"?>

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"

xmlns:tools="http://schemas.android.com/tools"

android:id="@+id/activity_main"

android:layout_width="match_parent"

android:layout_height="match_parent"

android:orientation="vertical"

tools:context=".MainActivity">

<android.support.v7.widget.RecyclerView

android:id="@+id/my_recycler_view"

android:scrollbars="vertical"

android:layout_width="match_parent"

android:layout_height="match_parent"/>

</LinearLayout>

　
RecyclerView オブジェクトのハンドルを取得してレイアウトマネージャーに接続し、アダプターにデータセットを渡します。
データセットとして20個の要素を持つ配列で設定してみます。
MainActivity.java

import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.support.v7.widget.LinearLayoutManager;
import android.support.v7.widget.RecyclerView;

public class MainActivity extends AppCompatActivity {

    private RecyclerView mRecyclerView;
    private RecyclerView.Adapter mAdapter;
    private RecyclerView.LayoutManager mLayoutManager;

    private String[] myDataset = new String[20];


    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        mRecyclerView = (RecyclerView) findViewById(R.id.my_recycler_view);

        // use this setting to improve performance if you know that changes
        // in content do not change the layout size of the RecyclerView
        mRecyclerView.setHasFixedSize(true);

        // use a linear layout manager
        mLayoutManager = new LinearLayoutManager(this);

        mRecyclerView.setLayoutManager(mLayoutManager);

        for(int i=0; i<myDataset.length; i++) {
            myDataset[i] = "Data_0"+String.valueOf(i);
        }

        // specify an adapter (see also next example)
        mAdapter = new MyAdapter(myDataset);
        mRecyclerView.setAdapter(mAdapter);
    }

}

import android.support.v7.app.AppCompatActivity;

import android.os.Bundle;

import android.support.v7.widget.LinearLayoutManager;

import android.support.v7.widget.RecyclerView;

public class MainActivity extends AppCompatActivity {

private RecyclerView mRecyclerView;

private RecyclerView.Adapter mAdapter;

private RecyclerView.LayoutManager mLayoutManager;

private String[] myDataset = new String[20];

@Override

protected void onCreate(Bundle savedInstanceState) {

super.onCreate(savedInstanceState);

setContentView(R.layout.activity_main);

mRecyclerView = (RecyclerView) findViewById(R.id.my_recycler_view);

// use this setting to improve performance if you know that changes

// in content do not change the layout size of the RecyclerView

mRecyclerView.setHasFixedSize(true);

// use a linear layout manager

mLayoutManager = new LinearLayoutManager(this);

mRecyclerView.setLayoutManager(mLayoutManager);

for(int i=0; i<myDataset.length; i++) {

myDataset[i] = "Data_0"+String.valueOf(i);

}

// specify an adapter (see also next example)

mAdapter = new MyAdapter(myDataset);

mRecyclerView.setAdapter(mAdapter);

}

　
Adapterですが、別ファイルとして作成しましたので、元の例と異なる箇所がでてきます。
MyAdapter.java

import android.support.v7.widget.RecyclerView;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.TextView;

public class MyAdapter extends RecyclerView.Adapter<MyAdapter.ViewHolder> {

    private String[] mDataset = new String[20];

    // Provide a reference to the views for each data item
    // Complex data items may need more than one view per item, and
    // you provide access to all the views for a data item in a view holder
    public static class ViewHolder extends RecyclerView.ViewHolder {

        // each data item is just a string in this case
        public TextView mTextView;

        public ViewHolder(View v) {
            super(v);
            mTextView = (TextView)v.findViewById(R.id.text_view);
        }
    }

    // Provide a suitable constructor (depends on the kind of dataset)
    public MyAdapter(String[] myDataset) {
        mDataset = myDataset;
    }

    // Create new views (invoked by the layout manager)
    @Override
    public ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
        // create a new view
        View view = LayoutInflater.from(parent.getContext())
                .inflate(R.layout.my_text_view, parent, false);
        
        // set the view's size, margins, paddings and layout parameters


        ViewHolder vh = new ViewHolder(view);
        return vh;
    }

    // Replace the contents of a view (invoked by the layout manager)
    @Override
    public void onBindViewHolder(ViewHolder holder, int position) {
        // - get element from your dataset at this position
        // - replace the contents of the view with that element
        holder.mTextView.setText(mDataset[position]);
    }

    // Return the size of your dataset (invoked by the layout manager)
    @Override
    public int getItemCount() {
        return mDataset.length;
    }
}

import android.support.v7.widget.RecyclerView;

import android.view.LayoutInflater;

import android.view.View;

import android.view.ViewGroup;

import android.widget.TextView;

public class MyAdapter extends RecyclerView.Adapter<MyAdapter.ViewHolder> {

private String[] mDataset = new String[20];

// Provide a reference to the views for each data item

// Complex data items may need more than one view per item, and

// you provide access to all the views for a data item in a view holder

public static class ViewHolder extends RecyclerView.ViewHolder {

// each data item is just a string in this case

public TextView mTextView;

public ViewHolder(View v) {

super(v);

mTextView = (TextView)v.findViewById(R.id.text_view);

}

// Provide a suitable constructor (depends on the kind of dataset)

public MyAdapter(String[] myDataset) {

mDataset = myDataset;

}

// Create new views (invoked by the layout manager)

@Override

public ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {

// create a new view

View view = LayoutInflater.from(parent.getContext())

.inflate(R.layout.my_text_view, parent, false);

// set the view's size, margins, paddings and layout parameters

ViewHolder vh = new ViewHolder(view);

return vh;

}

// Replace the contents of a view (invoked by the layout manager)

@Override

public void onBindViewHolder(ViewHolder holder, int position) {

// - get element from your dataset at this position

// - replace the contents of the view with that element

holder.mTextView.setText(mDataset[position]);

}

// Return the size of your dataset (invoked by the layout manager)

@Override

public int getItemCount() {

return mDataset.length;

}

　
cellとなる部分はListViewと同じように要素のレイアウトで作ります
my_text_view.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="wrap_content">

    <TextView
        android:id="@+id/text_view"
        android:layout_width="wrap_content"
        android:layout_height="50dp" />

</LinearLayout>

<?xml version="1.0" encoding="utf-8"?>

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"

android:layout_width="match_parent"

android:layout_height="wrap_content">

<TextView

android:id="@+id/text_view"

android:layout_width="wrap_content"

android:layout_height="50dp" />

</LinearLayout>

　
ここで注意するところは、layout_heightを限定しないとセルの高さがとんでもなく広がってしまうことがあります。
　
ここまで来てもまだエラーが残っていると思いますがライブラリーを追加しないといけません
com.android.support:recyclerview-v7
なお、このバージョンはビルドツールのバージョンと合っていないとエラーになることもありますので、それぞれの環境で調整してください。
build.gradle

dependencies {
    ...
    compile 'com.android.support:recyclerview-v7:25.1.0'
}

dependencies {

...

compile 'com.android.support:recyclerview-v7:25.1.0'

}

　
これでリストがスクロールするRecyclerViewの簡単な例ができたと思います。
　

　
しかし、これは境界ラインも無いしカスタマイズで作り込む必要があります。
逆にいうとListViewのカスタマイズには限界があったところを柔軟に拡張したということでしょうか。

RecyclerViewで画像とテキストのリストを作成

　
いままでの例を元に、画像と文字列を組み合わせた構成されるcellを作ってみたいと思います。
また、データセットも追加・削除・移動を前提にするためArrayListを使います。
また双方向連結リストのLinkedListを使用すれば削除・追加などが早くなるようです。
　
MainActivity.java

import android.app.Activity;
import android.os.Bundle;
import android.support.v7.widget.LinearLayoutManager;
import android.support.v7.widget.RecyclerView;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;

public class MainActivity extends Activity {

    private RecyclerView mRecyclerView;
    private RecyclerView.Adapter mAdapter;
    private RecyclerView.LayoutManager mLayoutManager;

    // ArrayListを定義
    private List<Integer> itemImages;
    private List<String> itemNames;
    private List<String> itemEmails;

    private static final String[] names = {
            "katakuriko",
            "kurumi",
            "mai",
            "miki",
            "nagi",
            "saya",
            "toko",
            "yuka",
            "yumiko",
            "yuyu"
    };

    // それぞれの画像ファイルをdarawableに入れます
    // ArrayListにコピーするためintからInteger型にしました
    private static final Integer[] photos = {
            R.drawable.katakuriko,
            R.drawable.kurumi,
            R.drawable.mai,
            R.drawable.miki,
            R.drawable.nagi,
            R.drawable.saya,
            R.drawable.toko,
            R.drawable.yuka,
            R.drawable.yumiko,
            R.drawable.yuyu
    };

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        mRecyclerView = (RecyclerView) findViewById(R.id.my_recycler_view);

        // use this setting to improve performance if you know that changes
        // in content do not change the layout size of the RecyclerView
        mRecyclerView.setHasFixedSize(true);

        // use a linear layout manager
        mLayoutManager = new LinearLayoutManager(this);

        mRecyclerView.setLayoutManager(mLayoutManager);

        // 配列をArrayListにコピー
        itemNames = new ArrayList<String>(Arrays.asList(names));
        itemImages = new ArrayList<Integer>(Arrays.asList(photos));

        itemEmails = new ArrayList<String>();
        for(int i=0; i<itemNames.size() ;i++ ){
            String str = itemNames.get(i)+"@gmail.com";
            itemEmails.add(str);
        }

        // specify an adapter (see also next example)
        mAdapter = new MyAdapter(itemImages, itemNames, itemEmails);
        mRecyclerView.setAdapter(mAdapter);
    }

}

import android.app.Activity;

import android.os.Bundle;

import android.support.v7.widget.LinearLayoutManager;

import android.support.v7.widget.RecyclerView;

import java.util.ArrayList;

import java.util.Arrays;

import java.util.List;

public class MainActivity extends Activity {

private RecyclerView mRecyclerView;

private RecyclerView.Adapter mAdapter;

private RecyclerView.LayoutManager mLayoutManager;

// ArrayListを定義

private List<Integer> itemImages;

private List<String> itemNames;

private List<String> itemEmails;

private static final String[] names = {

"katakuriko",

"kurumi",

"mai",

"miki",

"nagi",

"saya",

"toko",

"yuka",

"yumiko",

"yuyu"

};

// それぞれの画像ファイルをdarawableに入れます

// ArrayListにコピーするためintからInteger型にしました

private static final Integer[] photos = {

R.drawable.katakuriko,

R.drawable.kurumi,

R.drawable.mai,

R.drawable.miki,

R.drawable.nagi,

R.drawable.saya,

R.drawable.toko,

R.drawable.yuka,

R.drawable.yumiko,

R.drawable.yuyu

};

@Override

protected void onCreate(Bundle savedInstanceState) {

super.onCreate(savedInstanceState);

setContentView(R.layout.activity_main);

mRecyclerView = (RecyclerView) findViewById(R.id.my_recycler_view);

// use this setting to improve performance if you know that changes

// in content do not change the layout size of the RecyclerView

mRecyclerView.setHasFixedSize(true);

// use a linear layout manager

mLayoutManager = new LinearLayoutManager(this);

mRecyclerView.setLayoutManager(mLayoutManager);

// 配列をArrayListにコピー

itemNames = new ArrayList<String>(Arrays.asList(names));

itemImages = new ArrayList<Integer>(Arrays.asList(photos));

itemEmails = new ArrayList<String>();

for(int i=0; i<itemNames.size() ;i++ ){

String str = itemNames.get(i)+"@gmail.com";

itemEmails.add(str);

}

// specify an adapter (see also next example)

mAdapter = new MyAdapter(itemImages, itemNames, itemEmails);

mRecyclerView.setAdapter(mAdapter);

}

　
MyAdapter.java

import android.support.v7.widget.RecyclerView;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ImageView;
import android.widget.TextView;

import java.util.List;


public class MyAdapter extends RecyclerView.Adapter<MyAdapter.ViewHolder> {

    private List<Integer> iImages;
    private List<String> iNames;
    private List<String> iEmails;

    // Provide a reference to the views for each data item
    // Complex data items may need more than one view per item, and
    // you provide access to all the views for a data item in a view holder
    public static class ViewHolder extends RecyclerView.ViewHolder {
        // each data item is just a string in this case
        public ImageView imageView;
        public TextView textView;
        public TextView emailView;

        public ViewHolder(View v) {
            super(v);
            imageView = (ImageView)v.findViewById(R.id.image_view);
            textView = (TextView)v.findViewById(R.id.text_view);
            emailView = (TextView)v.findViewById(R.id.email_view);

        }
    }

    // Provide a suitable constructor (depends on the kind of dataset)
    public MyAdapter(List<Integer> itemImages, List<String> itemNames, List<String> itemEmails) {
        this.iImages = itemImages;
        this.iNames = itemNames;
        this.iEmails = itemEmails;

    }

    // Create new views (invoked by the layout manager)
    @Override
    public ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
        // create a new view
        View view = LayoutInflater.from(parent.getContext())
                .inflate(R.layout.my_text_view, parent, false);

        // set the view's size, margins, paddings and layout parameters


        ViewHolder vh = new ViewHolder(view);
        return vh;
    }

    // Replace the contents of a view (invoked by the layout manager)
    @Override
    public void onBindViewHolder(ViewHolder holder, int position) {
        // - get element from your dataset at this position
        // - replace the contents of the view with that element
        holder.imageView.setImageResource(iImages.get(position));
        holder.textView.setText(iNames.get(position));
        holder.emailView.setText(iEmails.get(position));
    }

    // Return the size of your dataset (invoked by the layout manager)
    @Override
    public int getItemCount() {
        return iNames.size();
    }
}

import android.support.v7.widget.RecyclerView;

import android.view.LayoutInflater;

import android.view.View;

import android.view.ViewGroup;

import android.widget.ImageView;

import android.widget.TextView;

import java.util.List;

public class MyAdapter extends RecyclerView.Adapter<MyAdapter.ViewHolder> {

private List<Integer> iImages;

private List<String> iNames;

private List<String> iEmails;

// Provide a reference to the views for each data item

// Complex data items may need more than one view per item, and

// you provide access to all the views for a data item in a view holder

public static class ViewHolder extends RecyclerView.ViewHolder {

// each data item is just a string in this case

public ImageView imageView;

public TextView textView;

public TextView emailView;

public ViewHolder(View v) {

super(v);

imageView = (ImageView)v.findViewById(R.id.image_view);

textView = (TextView)v.findViewById(R.id.text_view);

emailView = (TextView)v.findViewById(R.id.email_view);

}

// Provide a suitable constructor (depends on the kind of dataset)

public MyAdapter(List<Integer> itemImages, List<String> itemNames, List<String> itemEmails) {

this.iImages = itemImages;

this.iNames = itemNames;

this.iEmails = itemEmails;

}

// Create new views (invoked by the layout manager)

@Override

public ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {

// create a new view

View view = LayoutInflater.from(parent.getContext())

.inflate(R.layout.my_text_view, parent, false);

// set the view's size, margins, paddings and layout parameters

ViewHolder vh = new ViewHolder(view);

return vh;

}

// Replace the contents of a view (invoked by the layout manager)

@Override

public void onBindViewHolder(ViewHolder holder, int position) {

// - get element from your dataset at this position

// - replace the contents of the view with that element

holder.imageView.setImageResource(iImages.get(position));

holder.textView.setText(iNames.get(position));

holder.emailView.setText(iEmails.get(position));

}

// Return the size of your dataset (invoked by the layout manager)

@Override

public int getItemCount() {

return iNames.size();

}

　
activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/activity_main"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    android:paddingTop="20dp"
    android:background="#fac"
    tools:context=".MainActivity">


    <!-- A RecyclerView with some commonly used attributes -->
    <android.support.v7.widget.RecyclerView
        android:id="@+id/my_recycler_view"
        android:scrollbars="vertical"
        android:layout_width="match_parent"
        android:layout_height="match_parent"/>

</LinearLayout>

<?xml version="1.0" encoding="utf-8"?>

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"

xmlns:tools="http://schemas.android.com/tools"

android:id="@+id/activity_main"

android:layout_width="match_parent"

android:layout_height="match_parent"

android:orientation="vertical"

android:paddingTop="20dp"

android:background="#fac"

tools:context=".MainActivity">

<android.support.v7.widget.RecyclerView

android:id="@+id/my_recycler_view"

android:scrollbars="vertical"

android:layout_width="match_parent"

android:layout_height="match_parent"/>

</LinearLayout>

　
cellのレイアウトは色々と設定しました
my_text_view.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="horizontal"
    android:layout_width="match_parent"
    android:paddingLeft="20dp"
    android:paddingTop="5dp"
    android:paddingRight="20dp"
    android:paddingBottom="5dp"
    android:background="#fac"
    android:layout_height="wrap_content">

    <RelativeLayout
        android:layout_width="wrap_content"
        android:layout_height="wrap_content">

        <ImageView
            android:background="#f44"
            android:layout_width="100dp"
            android:layout_height="100dp" />

        <ImageView
            android:id="@+id/image_view"
            android:layout_margin="2dp"
            android:layout_width="96dp"
            android:layout_height="96dp" />

    </RelativeLayout>

    <LinearLayout
        android:orientation="vertical"
        android:background="#cef"
        android:layout_weight="1"
        android:layout_width="0dp"
        android:layout_height="match_parent">

        <TextView
            android:id="@+id/text_view"
            android:textSize="24sp"
            android:textColor="#00f"
            android:paddingLeft="20dp"
            android:paddingTop="20dp"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content" />

        <TextView
            android:id="@+id/email_view"
            android:textSize="18sp"
            android:textColor="#00f"
            android:paddingLeft="20dp"
            android:layout_gravity="center_vertical"
            android:autoLink="email"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content" />
    </LinearLayout>

</LinearLayout>

<?xml version="1.0" encoding="utf-8"?>

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"

android:orientation="horizontal"

android:layout_width="match_parent"

android:paddingLeft="20dp"

android:paddingTop="5dp"

android:paddingRight="20dp"

android:paddingBottom="5dp"

android:background="#fac"

android:layout_height="wrap_content">

<RelativeLayout

android:layout_width="wrap_content"

android:layout_height="wrap_content">

<ImageView

android:background="#f44"

android:layout_width="100dp"

android:layout_height="100dp" />

<ImageView

android:id="@+id/image_view"

android:layout_margin="2dp"

android:layout_width="96dp"

android:layout_height="96dp" />

</RelativeLayout>

<LinearLayout

android:orientation="vertical"

android:background="#cef"

android:layout_weight="1"

android:layout_width="0dp"

android:layout_height="match_parent">

<TextView

android:id="@+id/text_view"

android:textSize="24sp"

android:textColor="#00f"

android:paddingLeft="20dp"

android:paddingTop="20dp"

android:layout_width="wrap_content"

android:layout_height="wrap_content" />

<TextView

android:id="@+id/email_view"

android:textSize="18sp"

android:textColor="#00f"

android:paddingLeft="20dp"

android:layout_gravity="center_vertical"

android:autoLink="email"

android:layout_width="wrap_content"

android:layout_height="wrap_content" />

</LinearLayout>

　
バージョンなどは自分の環境に合わせてください
build.gradle

apply plugin: 'com.android.application'

android {
    ...
}

dependencies {
    ...
    compile 'com.android.support:recyclerview-v7:25.1.0'
}

apply plugin: 'com.android.application'

android {

...

}

dependencies {

...

compile 'com.android.support:recyclerview-v7:25.1.0'

}

　
少しはましになったでしょうか
　
　
関連ページ:

RecyclerView の基本的な設定
RecyclerViewとItemTouchHelperでドラッグ&ドロップ

Reference:

リストとカードの作成