RecyclerView①

MainActivity.java

package com.example.recyclerviewdemo1;

import androidx.appcompat.app.AppCompatActivity;
import androidx.recyclerview.widget.LinearLayoutManager;
import androidx.recyclerview.widget.RecyclerView;

import android.os.Bundle;
import android.widget.LinearLayout;

public class MainActivity extends AppCompatActivity {

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

        RecyclerView recyclerView = findViewById(R.id.recyclerView);
        LinearLayoutManager linearLayoutManager = new LinearLayoutManager(this);
        recyclerView.setLayoutManager(linearLayoutManager);

        String[] data_array = {"abc","cde","efg","ghi","ijk","klm"};
        MyAdapter myAdapter = new MyAdapter(data_array);
        recyclerView.setAdapter(myAdapter);
    }
}

acitivity_main.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"
    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/recyclerView"
        android:layout_width="match_parent"
        android:layout_height="match_parent"/>

</LinearLayout>

MyAdapter.java

package com.example.recyclerviewdemo1;

import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;

import androidx.annotation.NonNull;
import androidx.recyclerview.widget.RecyclerView;

public class MyAdapter extends RecyclerView.Adapter<MyViewHolder> {
    private String[] dataSet;


    public MyAdapter(String[] dateArray) {
        dataSet = dateArray;

    }

    @NonNull
    @Override
    public MyViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {

        LayoutInflater inflater = LayoutInflater.from(parent.getContext());
        View view = inflater.inflate(R.layout.my_text_view,parent,false);
        MyViewHolder myViewHolder = new MyViewHolder(view);
        return myViewHolder;
    }

    @Override
    public void onBindViewHolder(@NonNull MyViewHolder holder, int position) {

         holder.getTextView().setText(dataSet[position]);
    }

    @Override
    public int getItemCount() {
        return dataSet.length;
    }
}

MyViewHolder.java

package com.example.recyclerviewdemo1;

import android.view.View;
import android.widget.TextView;

import androidx.annotation.NonNull;
import androidx.recyclerview.widget.RecyclerView;

public class MyViewHolder extends RecyclerView.ViewHolder{
    private TextView textView;
    public MyViewHolder(@NonNull View itemView) {
        super(itemView);
        textView = itemView.findViewById(R.id.textView);
    }
    public TextView getTextView(){
        return textView;
    }
}

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/textView"
        android:layout_width="wrap_content"
        android:layout_height="50sp"/>

</LinearLayout>

build.gradle(app)に下記を追加します。

dependencies {
    implementation 'androidx.recyclerview:recyclerview:1.2.1'
    （省略）
}