Question

因此，我正在使用Volley从Thinkspeak.com API获取数据，该API具有将结果显示为JSON格式的有限结果。

这是Thinkspeak.com API的结果：

{
  "channel": {
    "id": "channel_id",
    "name": "SISTEM FDRS",
    "latitude": "lat",
    "longitude": "long",
    "field1": "Field Label 1",
    "field2": "Field Label 2",
    "field3": "Field Label 3",
    "field4": "Field Label 4",
    "field5": "Field Label 5",
    "field6": "Field Label 6",
    "created_at": "2019-01-20T02:01:36Z",
    "updated_at": "2019-06-27T08:06:29Z",
    "last_entry_id": 115
  },
  "feeds": [{
      "created_at": "2019-07-05T10:36:02Z",
      "entry_id": 106,
      "field1": "31.20",
      "field2": "64.30",
      "field3": "0.00",
      "field4": "2.95",
      "field5": "86",
      "field6": "2"
    },
    {
      "created_at": "2019-07-05T10:36:50Z",
      "entry_id": 107,
      "field1": "31.20",
      "field2": "64.67",
      "field3": "0.00",
      "field4": "2.41",
      "field5": "86",
      "field6": "2"
    },
    /* ... and so on .. */
  ]
}

由于可以通过使用addOnScrollListener方法达到RecyclerView的结尾，因此可以增加限制。

但是RecyclerView中显示的数据是重复的，我不知道为什么。

这是活动代码：

public class FFMCActivity extends AppCompatActivity {

  private List < Feed > feedList;
  private RecyclerView recyclerView;

  private String url = "https://api.thingspeak.com/channels/id/feeds.json?api_key=api_key&results=";
  private int load_results = 1;

  AdapterFFMC adapterFFMC;

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

    recyclerView = findViewById(R.id.recyclerview);
    recyclerView.setHasFixedSize(true);
    recyclerView.setNestedScrollingEnabled(false);
    recyclerView.setLayoutManager(new LinearLayoutManager(this));
    feedList = new ArrayList < > ();
    adapterFFMC = new AdapterFFMC(feedList);
    recyclerView.setAdapter(adapterFFMC);

    getData(load_results);

    recyclerView.addOnScrollListener(new RecyclerView.OnScrollListener() {
      @Override
      public void onScrolled(RecyclerView recyclerView, int dx, int dy) {
        if (recyclerView.getAdapter().getItemCount() != 0) {
          int lastVisibleItemPosition = ((LinearLayoutManager) recyclerView.getLayoutManager()).findLastCompletelyVisibleItemPosition();
          if (lastVisibleItemPosition != RecyclerView.NO_POSITION && lastVisibleItemPosition == recyclerView.getAdapter().getItemCount() - 1) {
            getData(load_results++);
            Toast.makeText(FFMCActivity.this, "Data loaded: " + load_results, Toast.LENGTH_SHORT).show();
          }

        }
      }
    });

  }

  private void getData(int results) {

    JsonObjectRequest jsonObjectRequest = new JsonObjectRequest(
      Request.Method.GET, url + results,
      null,
      new Response.Listener < JSONObject > () {
        @Override
        public void onResponse(JSONObject response) {

          JSONArray Jarray = null;
          try {
            Jarray = response.getJSONArray("feeds");
            for (int i = 0; i < Jarray.length(); i++) {

              JSONObject feed = Jarray.getJSONObject(i);
              feedList.add(new Feed(
                feed.getString("created_at"),
                feed.getString("entry_id"),
                feed.getString("field1"),
                feed.getString("field2"),
                feed.getString("field3"),
                feed.getString("field4"),
                feed.getString("field5"),
                feed.getString("field6")
              ));

            }
            Collections.sort(feedList, new Comparator < Feed > () {
              @Override
              public int compare(Feed feed1, Feed feed2) {
                if (Integer.parseInt(feed1.getEntry_id()) > Integer.parseInt(feed2.getEntry_id())) {
                  return -1;
                } else {
                  return 1;
                }
              }
            });
            adapterFFMC.notifyDataSetChanged();
          } catch (JSONException e) {
            Log.e("VolleyError", "JSON Parsing Error: " + e.getMessage());
          }
        }
      },
      new Response.ErrorListener() {
        @Override
        public void onErrorResponse(VolleyError error) {
          Log.e("VolleyError", "JSON Response Error: " + error.getMessage());

        }
      }
    );

    RequestQueue requestQueue = Volley.newRequestQueue(this);
    requestQueue.add(jsonObjectRequest);
  }

}

这是适配器代码：

public class AdapterFFMC extends RecyclerView.Adapter < AdapterFFMC.ViewHolder > {
  private List < Feed > dataFFMC;

  public AdapterFFMC(List < Feed > dataFFMC) {
    this.dataFFMC = dataFFMC;
  }

  @Override
  public ViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {

    View v = LayoutInflater.from(parent.getContext()).inflate(R.layout.item_ffmc, parent, false);
    ViewHolder holder = new ViewHolder(v);

    return holder;

  }

  @Override
  public void onBindViewHolder(@NonNull ViewHolder holder, int position) {

    Feed feed = dataFFMC.get(position);
    holder.created_at.setText(feed.getCreated_at());
    holder.created_day.setText(feed.getCreated_at());
    holder.entry_id.setText(feed.getEntry_id());
    holder.field_1.setText(feed.getField_1());
    holder.field_2.setText(feed.getField_2());
    holder.field_3.setText(feed.getField_3());
    holder.field_4.setText(feed.getField_4());
    holder.field_5.setText(feed.getField_5());
    holder.field_6.setText(feed.getField_6());

  }

  @Override
  public long getItemId(int position) {
    return position;
  }

  @Override
  public int getItemViewType(int position) {
    return position;
  }

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


  public class ViewHolder extends RecyclerView.ViewHolder {

    TextView created_at, created_day, entry_id, field_1, field_2, field_3, field_4, field_5, field_6;

    public ViewHolder(View itemView) {

      super(itemView);

      created_at = itemView.findViewById(R.id.created_at);
      created_day = itemView.findViewById(R.id.created_day);
      entry_id = itemView.findViewById(R.id.entry_id);
      field_1 = itemView.findViewById(R.id.field_1);
      field_2 = itemView.findViewById(R.id.field_2);
      field_3 = itemView.findViewById(R.id.field_3);
      field_4 = itemView.findViewById(R.id.field_4);
      field_5 = itemView.findViewById(R.id.field_5);
      field_6 = itemView.findViewById(R.id.field_6);
    }
  }
}

如何防止上面的代码重复结果？

任何帮助将不胜感激谢谢。

Answer 1

将代码的顺序更改为此。

    feedList = new ArrayList < > ();
    getData(load_results);
    adapterFFMC = new AdapterFFMC(feedList);
    recyclerView.setAdapter(adapterFFMC);

设置阵列适配器后，您正在初始化阵列。

为什么在RecyclerView中加载更多数据时会出现重复项？

1 个答案: