Question

我正在尝试使用来自SQLite数据库内容的数据加载recyclerview。但它不起作用

这就是我所做的

活动类

public class ViewMembership extends AppCompatActivity {
private  RecyclerView recyclerView;
private  membership_view_recycler_adapter m;

private  DBHelper dbHelper;


public List<membership_recycler_model> membershipList=new ArrayList<>();
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_view_membership);
    dbHelper=new DBHelper(this);

    ////////////////////////////////////////////////////////////////////////////

    recyclerView=(RecyclerView) findViewById(R.id.View_Membership_Recycler);
    m=new membership_view_recycler_adapter(membershipList);
    RecyclerView.LayoutManager layoutManager=new LinearLayoutManager(getApplicationContext());
    recyclerView.setLayoutManager(layoutManager);
    recyclerView.setItemAnimator(new DefaultItemAnimator());

    recyclerView.addItemDecoration(new DividerItemDecoration(this, LinearLayoutManager.VERTICAL));

    recyclerView.setAdapter(m);

    prepare_membership();

    //////////////////////////////////////////////////////////////////////////

}
public void  prepare_membership()
{
    System.out.println("#######################Prepare_membership called");
    membershipList=dbHelper.membership_for_recycler_view();
   m.notifyDataSetChanged();
}}

适配器类

public class membership_view_recycler_adapter extends RecyclerView.Adapter<membership_view_recycler_adapter.MyViewHolder> {

public class MyViewHolder extends RecyclerView.ViewHolder {
    public TextView name,region;
    public MyViewHolder(View itemView) {
        super(itemView);
        name=(TextView) itemView.findViewById(R.id.membership_name_textview);
        region=(TextView) itemView.findViewById(R.id.membership_region_textview);
    }
}


public membership_view_recycler_adapter(List<membership_recycler_model> membership_list) {
    this.membership_list = membership_list;
}

private List<membership_recycler_model> membership_list;



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

@Override
public void onBindViewHolder(MyViewHolder holder, int position) {
    membership_recycler_model membership=membership_list.get(position);
    holder.name.setText(membership.getMembership_name());
    holder.region.setText(membership.getRegion());
}

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

我没有编译错误，应用程序没有抛出任何异常。 dbHelper.membership_for_recycler_view（）返回适当的值。我是Android的新手。我是在教程的帮助下完成的。我做错了什么？

Answer 1

我认为这里的问题是你在呼叫prepare_membership() 稍后运行并在使用空列表之前将数据传递到适配器。尝试进行以下更改：

在适配器中添加新方法 -

       public void refreshData(List<membership_recycler_model> membership_list){
            this.membership_list = membership_list;
            notifyDataSetChanged();
        }

在prepare_membership（）函数内部从db获取列表后调用此方法，即m.refreshData(membershipList)

`

RecyclerView没有填充数据

1 个答案: