Question

我从webservices获取数据比我必须在recyclerView中显示这些数据...我在asyncTest的AsyncTask中设置我的recyclelerView因为我必须首先获取数据。问题是我的活动中没有View，每次收到此消息...
这是我的Main_activity ......

    public class Store_Items_Display extends AppCompatActivity
    {
    public String s;
    private RecyclerView recyclerView;
    private DataAdapter dataAdapter;
    private ArrayList<String> arrayList = new ArrayList<>();

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

        recyclerView = (RecyclerView) findViewById(R.id.recycleView);
        dataAdapter = new DataAdapter(arrayList);
        Log.i("ArrayList  size :::", String.valueOf(arrayList.size()));
        RecyclerView.LayoutManager layoutManager = new LinearLayoutManager(getApplicationContext());
        recyclerView.setHasFixedSize(true);
        recyclerView.setLayoutManager(layoutManager);
        recyclerView.setItemAnimator(new DefaultItemAnimator());
        recyclerView.setAdapter(dataAdapter);

        new Connection().execute();

        Intent intent = getIntent();
        Bundle bundle = intent.getExtras();
        if (bundle != null)
        {
            s = (String) bundle.get("userName");
            Log.i("Oncreate UserName ::: ", "Hamza");
        }
        else
        {
            Log.i("Data in intent ::;", "is Null");
        }

        getSupportActionBar().setDisplayHomeAsUpEnabled(true);
        getSupportActionBar().setHomeButtonEnabled(true);
        Button submitButton = (Button) findViewById(R.id.button8);
        submitButton.setOnClickListener(new View.OnClickListener()
        {
            @Override
            public void onClick(View v)
            {
                Toast.makeText(Store_Items_Display.this, "Submitted", Toast.LENGTH_SHORT).show();
            }
        });
    }


    public boolean onOptionsItemSelected(MenuItem item)
    {
        Intent myIntent = new Intent(getApplicationContext(), StoreFirstActivity.class);
        startActivityForResult(myIntent, 0);
        return true;
    }

    class Connection extends AsyncTask<Void, Void, Void>
    {
        StringBuilder result = new StringBuilder();
        final String TAG = "Items in ArrayList :::";

        @Override
        protected void onPreExecute()
        {
            super.onPreExecute();
            Toast.makeText(Store_Items_Display.this, "Welcome", Toast.LENGTH_LONG);
        }

        @Override
        protected Void doInBackground(Void... params)
        {
            try
            {
                Log.i("User Name ::: ", "Hamza");
                URL url = new URL("http://10.0.3.2/FixItApp/GetData.php?user_name=khan"); // need changes here...
                HttpURLConnection httpUrlConnection = (HttpURLConnection) url.openConnection();
                InputStream in = new BufferedInputStream(httpUrlConnection.getInputStream());
                BufferedReader reader = new BufferedReader(new InputStreamReader(in));
                String line;
                while ((line = reader.readLine()) != null)
                {
                    result.append(line);
                }
                in.close();
                reader.close();
                if (!result.toString().equals(""))
                {
                    JSONObject jsonObject = new JSONObject(result.toString());
                    JSONArray jsonArray = new JSONArray(jsonObject.getString("user_data"));
                    for (int i = 0; i < jsonArray.length(); i++)
                    {
                        String serial = jsonArray.getJSONObject(i).getString("serial_number");
                        String items = jsonArray.getJSONObject(i).getString("items");
                        String brand = jsonArray.getJSONObject(i).getString("brand");
                        String price = jsonArray.getJSONObject(i).getString("price");
                        arrayList.add(serial);
                        arrayList.add(items);
                        arrayList.add(brand);
                        arrayList.add(price);
                        Log.i(TAG, serial);
                        Log.i(TAG, arrayList.toString());
                        Log.i("ArrayList Size :::", String.valueOf(arrayList.size()));
                    }
                }
                else
                {
                    Toast.makeText(Store_Items_Display.this, "No data found of this name", Toast.LENGTH_LONG);
                }
            }
            catch(Exception e)
            {
                e.printStackTrace();
            }
            return null;
        }

        @Override
        protected void onPostExecute(Void aVoid)
        {
            super.onPostExecute(aVoid);
            dataAdapter.notifyDataSetChanged();
        }
    }
}

这是我的DataAdapter类......

public class DataAdapter extends RecyclerView.Adapter<DataAdapter.MyViewHolder>
{
    private ArrayList<String> dataList;

    public DataAdapter(ArrayList<String> arrayList)
    {
        this.dataList = arrayList;
    }

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

    @Override
    public void onBindViewHolder(MyViewHolder holder, int position)
    {
        String items = dataList.get(position);
        holder.serial.setText(items);

    }

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

    class MyViewHolder extends RecyclerView.ViewHolder
    {
        public TextView serial;
        public TextView items;
        public TextView brand;
        public TextView price;
        public MyViewHolder(View itemView)
        {
            super(itemView);
            serial = (TextView) itemView.findViewById(R.id.serial);
            items = (TextView) itemView.findViewById(R.id.items);
            brand = (TextView) itemView.findViewById(R.id.brand);
            price = (TextView) itemView.findViewById(R.id.price);
        }
    }
}

Answer 1

代码在某些方面很糟糕。如果您每次获取数据时都设置了新适配器，那么notifyDataSetChanged()呼叫就没有意义了。但事实上你应该做的是替换数据，而不是适配器，然后只需在现有适配器上调用dataAdapter.notifyDataSetChanged();，让它知道数据已经改变。

RecyclerView：没有连接适配器;跳过布局？

1 个答案: