Android RecyclerView by Java

This is a similar contents of “Android RecyclerView“(kotlin). In this time, realize same function as Java

build.gradle

implementation 'androidx.recyclerview:recyclerview:1.1.0-beta04'

Coding Flow

1. Prepare row (item) layout
2. Prepare Activity layout
3. Prepare data class
4. Prepare Adapter
5. Add adapter to Activity

Flow is same as ListView

recyclerview_row.xml

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    xmlns:app="http://schemas.android.com/apk/res-auto">

    <ImageView
        android:id="@+id/mainicon"
        android:layout_width="60dp"
        android:layout_height="60dp"
        android:layout_marginStart="16dp"
        android:layout_marginTop="16dp"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent"
        android:src="@drawable/nogizaka"
        android:scaleType="fitCenter"/>

    <TextView
        android:id="@+id/mainname"
        android:layout_width="wrap_content"
        android:layout_height="0dp"
        android:layout_marginStart="8dp"
        app:layout_constraintStart_toEndOf="@id/mainicon"
        app:layout_constraintTop_toTopOf="@id/mainicon" />

    <TextView
        android:id="@+id/maindate"
        android:layout_width="wrap_content"
        android:layout_height="0dp"
        android:layout_marginStart="8dp"
        android:layout_marginTop="3dp"
        android:textSize="12sp"
        app:layout_constraintStart_toEndOf="@id/mainname"
        app:layout_constraintTop_toTopOf="@id/mainname" />

    <TextView
        android:id="@+id/content"
        android:layout_width="300dp"
        android:layout_height="0dp"
        android:layout_below="@+id/mainname"
        android:layout_marginStart="8dp"
        android:layout_marginTop="4dp"
        android:textStyle="bold"
        app:layout_constraintStart_toEndOf="@id/mainicon"
        app:layout_constraintTop_toBottomOf="@id/mainname" />


</androidx.constraintlayout.widget.ConstraintLayout>

activity_recyclerview.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:orientation="vertical"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <androidx.recyclerview.widget.RecyclerView
        android:id="@+id/listView"
        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_toTopOf="parent">
    </androidx.recyclerview.widget.RecyclerView>

</androidx.constraintlayout.widget.ConstraintLayout>

RecyclerData.java

@Data
public class RecyclerData {

    private String content;

    private String date;

    private String name;

    public RecyclerData(String content, String date, String name) {
        this.content = content;
        this.date = date;
        this.name = name;
    }
}

I use lombok for getter/setter, if you have interest in lombok, please check my other entry(Android getter/setter lombok).

RecyclerDataAdapter.java

public class RecyclerDataAdapter extends RecyclerView.Adapter<RecyclerDataAdapter.RecyclerDataHolder> {

    private List<RecyclerData> list;

    private Context context;

    class RecyclerDataHolder extends RecyclerView.ViewHolder {

        ImageView iconView;

        TextView nameTextView;

        TextView dateTextView;

        TextView contentTextView;

        public RecyclerDataHolder(View view) {
            super(view);
            this.iconView = view.findViewById(R.id.mainicon);
            this.nameTextView = view.findViewById(R.id.mainname);
            this.dateTextView = view.findViewById(R.id.maindate);
            this.contentTextView = view.findViewById(R.id.content);
        }
    }

    public RecyclerDataAdapter(Context context, List<RecyclerData> list) {
        super();
        this.list = list;
        this.context = context;
    }

    @NonNull
    @Override
    public RecyclerDataHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
        return new RecyclerDataHolder(LayoutInflater.from(context).inflate(R.layout.recyclerview_row, parent, false));
    }

    @Override
    public int getItemCount() {
        return list.size();
    }

    @Override
    public void onBindViewHolder(@NonNull RecyclerDataHolder holder, int position) {
        holder.iconView.setImageResource(R.drawable.nogizaka);
        holder.nameTextView.setText(list.get(position).getName());
        holder.dateTextView.setText(list.get(position).getDate());
        holder.contentTextView.setText(list.get(position).getContent());
    }
}

RecyclerViewActivity.java

public class RecyclerViewActivity extends Activity {

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

        RecyclerData recyclerData = new RecyclerData("Tsundere", "2019/12/25", "Saito, Asuka");
        recyclerData.getContent();
        recyclerData.getDate();
        recyclerData.getName();

        List<RecyclerData> list = new ArrayList<>();
        list.add(recyclerData);
        list.add(new RecyclerData("Kawaii", "2019/12/31", "Hori, Miona"));

        RecyclerDataAdapter recyclerDataAdapter = new RecyclerDataAdapter(this, list);
        RecyclerView recyclerView = findViewById(R.id.listView);
        recyclerView.setAdapter(recyclerDataAdapter);
        recyclerView.setLayoutManager(new LinearLayoutManager(this));
        recyclerDataAdapter.notifyDataSetChanged();
    }
}