使用recyclerview和retrofit时，无法显示获取的数据

implementation 'androidx.recyclerview:recyclerview:1.2.1'

implementation 'com.squareup.retrofit2:retrofit:2.9.0'
implementation 'com.squareup.retrofit2:converter-gson:2.9.0'

<androidx.recyclerview.widget.RecyclerView
    android:id="@+id/recyclerView"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical" />

public class MyAdapter extends RecyclerView.Adapter<MyAdapter.ViewHolder> {
    private List<DataItem> dataList;

    public MyAdapter(List<DataItem> dataList) {
        this.dataList = dataList;
    }

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

    @Override
    public void onBindViewHolder(@NonNull ViewHolder holder, int position) {
        DataItem item = dataList.get(position);
        holder.bindData(item);
    }

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

    public static class ViewHolder extends RecyclerView.ViewHolder {
        private TextView textView;

        public ViewHolder(@NonNull View itemView) {
            super(itemView);
            textView = itemView.findViewById(R.id.textView);
        }

        public void bindData(DataItem item) {
            textView.setText(item.getText());
        }
    }
}

public class MainActivity extends AppCompatActivity {
    private RecyclerView recyclerView;
    private MyAdapter adapter;

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

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

        // 创建Retrofit实例
        Retrofit retrofit = new Retrofit.Builder()
                .baseUrl("https://api.example.com/") // 设置API基础URL
                .addConverterFactory(GsonConverterFactory.create()) // 设置数据转换器为Gson
                .build();

        // 创建API接口实例
        MyApiService apiService = retrofit.create(MyApiService.class);

        // 发起网络请求
        Call<List<DataItem>> call = apiService.getData();
        call.enqueue(new Callback<List<DataItem>>() {
            @Override
            public void onResponse(Call<List<DataItem>> call, Response<List<DataItem>> response) {
                if (response.isSuccessful()) {
                    List<DataItem> dataList = response.body();
                    adapter = new MyAdapter(dataList);
                    recyclerView.setAdapter(adapter);
                } else {
                    // 处理请求失败的情况
                }
            }

            @Override
            public void onFailure(Call<List<DataItem>> call, Throwable t) {
                // 处理请求失败的情况
            }
        });
    }
}