Skapandet av en recycler view i android studio.

public class MainActivity extends AppCompatActivity {
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        SimpleAdapter adapter = new SimpleAdapter(generateSimpleList()); //PROBLEM!
        RecyclerView recyclerView = (RecyclerView)findViewById(R.id.simple_recyclerview);
        recyclerView.setHasFixedSize(true);
        recyclerView.setLayoutManager(new LinearLayoutManager(this));
        recyclerView.setAdapter(adapter);
    }

    private List<SimpleViewModel> generateSimpleList() {
        List<SimpleViewModel> simpleViewModelList = new ArrayList<>();
        for (int i = 0; i < 100; i++) {
            simpleViewModelList.add(new SimpleViewModel(String.format(Locale.US, "This is item %d", i)));
        }
        return simpleViewModelList;
    }
}

import androidx.annotation.NonNull;

public class SimpleViewModel {

    private String simpleText;

    public SimpleViewModel(@NonNull final String simpleText){
        setSimpleText(simpleText);
    }

    public String getSimpleText() {
        return simpleText;
    }

    public void setSimpleText(String simpleText) {
        this.simpleText = simpleText;
    }
}

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

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

import java.util.List;

public class SimpleAdapter extends RecyclerView.Adapter {

    @NonNull
    @Override
    public RecyclerView.ViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
        final View view = LayoutInflater.from(parent.getContext()).inflate(viewType, parent, false);
        return new SimpleViewHolder(view);
    }

    @Override
    public void onBindViewHolder(@NonNull RecyclerView.ViewHolder holder, int position) {
        ((SimpleViewHolder) holder).bindData(models.get(position)); //PROBLEM!
    }

    @Override
    public int getItemCount() {
        return models.size(); //PROBLEM!
    }

    @Override
    public int getItemViewType(int position) {
        return R.layout.item_simple_itemview;
    }
}

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

import androidx.recyclerview.widget.RecyclerView;

public class SimpleViewHolder extends RecyclerView.ViewHolder {

    private TextView simpleTextView;

    public SimpleViewHolder(final View itemView){
        super(itemView);
        simpleTextView = (TextView) itemView.findViewById(R.id.simple_text);
    }

    public void bindData(final SimpleViewModel viewModel){
        simpleTextView.setText(viewModel.getSimpleText());
    }
}

<?xml version="1.0" encoding="utf-8"?>
<FrameLayout  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/simple_recyclerview"
        android:layout_width="match_parent"
        android:layout_height="473dp" />

</FrameLayout>

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

    <TextView
        android:id="@+id/simple_text"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="This is some temp text" />

</FrameLayout>