android - RecyclerView 显示为空

Question

我对 recyclerview 很陌生，所以我尝试转换一个 ListView ，我得到了这个:

    public class WalletListRecyclerViewAdapter extends RecyclerView.Adapter<WalletListRecyclerViewAdapter.WalletItemHolder> {

    ArrayList<WalletItem> walletItemList;
    MainActivity context;
    private static LayoutInflater inflater=null;
    public WalletListRecyclerViewAdapter(MainActivity mainActivity, ArrayList<WalletItem> walletItemList) {
        // TODO Auto-generated constructor stub

        context = mainActivity;
        this.walletItemList = walletItemList;
        inflater = ( LayoutInflater )context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
    }

    @Override
    public WalletItemHolder onCreateViewHolder(final ViewGroup viewGroup, final int i) {

        View rowView;

        final DialogInterface.OnClickListener walletItemOnEditClickHandler = new DialogInterface.OnClickListener() {

            @Override
            public void onClick(DialogInterface dialog, int which) {

                WalletItem.onClickEditButton(viewGroup,context,walletItemList,i);
            }

        };

        final DialogInterface.OnClickListener walletItemOnDeleteClickHandler = new DialogInterface.OnClickListener() {

            @Override
            public void onClick(DialogInterface dialog, int which) {
                walletItemList.remove(i);
                RecyclerView rv = (RecyclerView) context.findViewById(R.id.recyclerView);
                context.recreate();
            }

        };

        View.OnClickListener walletItemOnClickHandler = new View.OnClickListener() {
            @Override
            public void onClick(View v) {

                AlertDialog.Builder builder = new AlertDialog.Builder(context);
                builder.setNeutralButton("Edit",walletItemOnEditClickHandler);
                builder.setPositiveButton("Delete",walletItemOnDeleteClickHandler);

                builder.show();
            }
        };

        rowView = inflater.inflate(R.layout.wallet_item, null);

        return new WalletItemHolder(rowView);
    }


    @Override
    public void onBindViewHolder(WalletItemHolder holder, int i) {
        WalletItem wi = walletItemList.get(i);
        SimpleDateFormat dateFormat = new SimpleDateFormat("E dd/MM/yyyy hh:mm");
        holder.tvDescription.setText(wi.getDescription());
        holder.tvAmount.setText(""+walletItemList.get(i).getAmount());
        holder.tvDate.setText(dateFormat.format(walletItemList.get(i).getDate()));
        holder.ivIcon.setImageResource(walletItemList.get(i).getImageResource());
    }

    public static class WalletItemHolder extends RecyclerView.ViewHolder {
        public TextView tvDescription;
        public TextView tvAmount;
        public TextView tvDate;
        public ImageView ivIcon;

        /**
        *Constructor
         **/
        public WalletItemHolder(View v) {
            super(v);
            tvDescription =  (TextView) v.findViewById(R.id.textDescription);
            tvAmount = (TextView)  v.findViewById(R.id.textAmount);
            tvDate = (TextView)  v.findViewById(R.id.textDate);
            ivIcon = (ImageView) v.findViewById(R.id.imageView1);
        }
    }

    @Override
    public int getItemCount() {
        // TODO Auto-generated method stub
        return walletItemList.size();
    }

    @Override
    public long getItemId(int position) {
        // TODO Auto-generated method stub
        return position;
    }
}

在我的 Activity 中使用

public class MainActivity extends AppCompatActivity {

private RecyclerView rv;
private Context context;
private MainActivity mainActivity = this;

private String m_DialogText = "";
private double m_DialogAmount = 0;
private WalletItem m_DialogResult = null;

private boolean drawn = false;

public static ArrayList<WalletItem> wlltList = new ArrayList<WalletItem>() ;// WalletItem.listBuilder(prgmImages, amountDummy, prgmNameList, dates);

private GoogleApiClient client;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
    setSupportActionBar(toolbar);

    context = this;

    wlltList.add(new WalletItem(R.drawable.testicongreen,15.0,"pippo",new Date()));

    rv = (RecyclerView) findViewById(R.id.recyclerView);
    if(wlltList != null) {
        rv.setAdapter(new WalletListRecyclerViewAdapter(this, wlltList));
    }

    FloatingActionButton fab = (FloatingActionButton) findViewById(R.id.fab);
    fab.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {

            WalletItem.onClickAddButton(view,mainActivity,wlltList);
        }
    });

    client = new GoogleApiClient.Builder(this).addApi(AppIndex.API).build();
}

ListView 工作正常，但我不知道我做错了什么，因为即使我添加了一些元素，RecyclerView 也显示为空

Answer 1

您还没有为您的 RecyclerView 设置 LayoutManager。在设置适配器之前添加以下行。

rv.setLayoutManager(new LinearLayoutManager(this));