android - 从 Activity 更新适配器中的 TextView

Question

当我点击按钮“btn”时，我想从 Activity SlotsActivity 更新适配器 (textViewNum) 中的 TextView

如何访问 TextView ？？请记住 listItems 不为空。

这是我的 Activity 代码:

public class SlotsActivity extends AppCompatActivity{

private RecyclerView recyclerView;
private MyAdapter adapter;
private List<ListItem> listItems;
private Button btn;

@SuppressLint("WrongViewCast")
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_slots);
    recyclerView = findViewById(R.id.recyclerview);
    recyclerView.setHasFixedSize(true);
    recyclerView.setLayoutManager(new LinearLayoutManager(this));
    listItems = new ArrayList<>();
    ....

    btn=findViewById(R.id.btn);
    btn.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {
            //i want to update the textview here
        }
    });

}

这是我的适配器:

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

    private List<ListItem> listItems ;
    private Context context;

    public MyAdapter(List<ListItem> listItems, Context context) {
        this.listItems = listItems;
        this.context = context;
    }
    ....

    @Override
    public void onBindViewHolder(@NonNull final ViewHolder holder, int position) {
        final ListItem listItem= listItems.get(position);
        //**I want to update this textView**
        holder.textViewNum.setText("N° slot : "+listItem.getNum()+"");
    }
      ....

    public class ViewHolder extends RecyclerView.ViewHolder implements View.OnClickListener{

        public TextView textViewNum;

        public ViewHolder(View itemView) {
            super(itemView);
            textViewNum = itemView.findViewById(R.id.textViewNum);
        }
    }
   }

Answer 1

一种方法是使用ViewHolder 作为SlotsActivity 的子类，并在父类中声明TextView 变量。喜欢

public class SlotsActivity extends AppCompatActivity{
private RecyclerView recyclerView;
private MyAdapter adapter;
....
TextView txtView;
.....
public class ViewHolder extends RecyclerView.ViewHolder implements View.OnClickListener{

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

这样您就可以访问和更改 TextView 值。