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ArrayList未显示在RecyclerView中

adapter android-recyclerview arraylist android
  •  -3
  • random1234  · 技术社区  · 9 年前

    这是我到目前为止的代码,但RecyclerView没有显示任何内容。

    所有代码更新为我的当前代码 

    public class MainActivity extends AppCompatActivity {

private ActivityMainViewModel viewmodel;
RecyclerView recyclerView;
MainAdapter mAdapter;
public static ArrayList<Integer> rideList = new ArrayList<>();

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

    ActivityMainBinding binding = DataBindingUtil.setContentView(this, R.layout.activity_main);

    viewmodel = new ActivityMainViewModel();
    binding.setViewmodel(viewmodel);

    recyclerView = (RecyclerView) findViewById(R.id.recycler_view);
    recyclerView.setHasFixedSize(true);
    recyclerView.setLayoutManager(new LinearLayoutManager(this));
    mAdapter = new MainAdapter(rideList);
    recyclerView.setAdapter(mAdapter);
}

    以下是MainAdapter类: 

    class MainAdapter extends android.support.v7.widget.RecyclerView.Adapter<MainAdapter.ViewHolder> {

private ArrayList<Integer> rideList;

public MainAdapter(ArrayList<Integer> rideList)
{
    this.rideList = rideList;
}

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

@Override
public void onBindViewHolder(MainAdapter.ViewHolder holder, int position)
{
    holder.rideHeight.setText(String.valueOf(rideList.get(position)));
}

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

public class ViewHolder extends RecyclerView.ViewHolder {

    public TextView rideHeight;
    public ViewHolder(View itemView) {
        super(itemView);

        rideHeight = (TextView) itemView.findViewById(R.id.rideHeight_textView);
    }
}

    } 

    <?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical"
android:layout_width="match_parent"
android:layout_height="wrap_content">

<TextView
    android:id="@+id/rideHeight_textView"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:textSize="20sp"/>

</LinearLayout>

    我知道这看起来可能很混乱,但那是因为我一直在谷歌和youtube上搜索如何使用RecyclerView,所以我可能混合了不同的教程,自己尝试了一些东西。

    谢谢

    编辑:根据请求添加的JsonData代码: 

    public class JsonData
{
public ObservableField<String> dropHeight = new ObservableField<>();
public ObservableField<String> rideCount = new ObservableField<>();
int eID;
int sID;

public JsonData()
{
    dropHeight.set("");
    rideCount.set("");
}

public void downloadFromSkistar()
{
    if (SettingsActivity.submitClicked)
    {
        eID = SettingsActivity.x;
        sID = SettingsActivity.y;
    }
    else
    {
        eID = 3206;
        sID = 11;
    }

    try
    {
        URL url = new URL("https://www.skistar.com/myskistar/api/v2/views/statisticspage.json?entityId=" + eID + "&seasonId=" + sID + " ");
        HttpURLConnection conn = (HttpURLConnection) url.openConnection();
        conn.setReadTimeout(10000 /* milliseconds */);
        conn.setConnectTimeout(15000 /* milliseconds */);
        conn.setRequestMethod("GET");
        // Starts the query
        conn.connect();

        int response = conn.getResponseCode();
        Log.i("AndroidExample", "Response: " + response);

        if (response == 200)
        {
            String json = getJson(conn.getInputStream());

            JSONObject jsonObject = new JSONObject(json);
            JSONArray jsonArray = jsonObject.getJSONArray("rideStatistics");

            int reponame = 0;
            int rHeight = 0;

            for (int i = 0; i < jsonArray.length(); i++)
            {
                JSONObject skiRun = jsonArray.getJSONObject(i);
                reponame += skiRun.getInt("height");

                rHeight += skiRun.getInt("height");
                MainActivity.rideList.add(new Integer(rHeight));
                rHeight = 0;
            }
            final int height = reponame;
            final int count =  jsonArray.length();

            new Handler(Looper.getMainLooper()).post(new Runnable() {
                @Override
                public void run() {
                    dropHeight.set("" + height);
                    rideCount.set("" + count);
                }
            });
        }
    }
    catch (Exception e)
    {
        Log.i("AndroidExample", "Error");
    }
    finally
    {
    }
}

private String getJson(InputStream stream) throws IOException
{
    BufferedReader reader;
    reader = new BufferedReader(new InputStreamReader(stream, "UTF-8"));

    StringBuilder builder = new StringBuilder();
    String line;

    while ((line = reader.readLine()) != null) {
        builder.append(line + '\n');
    }
    //Should be placed in finally
    stream.close();
    return builder.toString();
}
}
    4 回复  |  直到 9 年前
        1
  •  0
  •   Enamul Haque    9 年前 

    1. public class CustomModel {
 private  int it;

  public int getIt() {
   return it;
   }

  public void setIt(int it) {
   this.it = it;
    }
 }

    2. 适配器。。。 

           private class  MainAdapter extends RecyclerView.Adapter<MainAdapter.ViewHolder>{

public MainAdapter(ArrayList<CustomModel> list){

    dataSet = list;
}

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

    View itemLayoutView = LayoutInflater.from(viewGroup.getContext()).inflate(
            R.layout.row, null);

    itemLayoutView.setLayoutParams(new RecyclerView.LayoutParams(RecyclerView.LayoutParams.MATCH_PARENT, RecyclerView.LayoutParams.WRAP_CONTENT));

    MainAdapter.ViewHolder viewHolder = new MainAdapter.ViewHolder(itemLayoutView);

    return viewHolder;
}


@Override
public void onBindViewHolder(ViewHolder viewHolder, int position) {
    CustomModel cardModel = dataSet.get(position);
    viewHolder.rideHeight_textView.setText(String.valueOf(cardModel.getId()));

}

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

public void updateList(List<CustomModel> temp) {
    dataSet = (ArrayList<CustomModel>) temp;
    notifyDataSetChanged();
}

public  class ViewHolder extends RecyclerView.ViewHolder {

    public TextView rideHeight_textView;



    public ViewHolder(View itemLayoutView) {
        super(itemLayoutView);

        rideHeight_textView = (TextView) itemLayoutView  .findViewById(R.id.rideHeight_textView);


        itemLayoutView.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
               //action ****
            }
        });
    }
     }

}

    3. 打个电话就行了 

       ArrayList<CustomModel> menuList = new ArrayList<>();
CustomModel c = new CustomModel();
c.setIt(1);
recyclerView.setHasFixedSize(true);
// ListView
recyclerView.setLayoutManager(new LinearLayoutManager(Your activity.this));
// create an Object for Adapter
MainAdapter mAdapter = new MainAdapter(menuList);
// set the adapter object to the Recyclerview
recyclerView.setAdapter(mAdapter);


    4.  <?xml version="1.0" encoding="utf-8"?>
  <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
   android:orientation="vertical"
   android:background="#ffffff"
    android:padding="@dimen/activity_vertical_margin"
    android:layout_width="match_parent"
     android:layout_height="wrap_content">

<TextView
 android:id="@+id/rideHeight_textView"
 android:layout_width="match_parent"
  android:layout_height="wrap_content"
 android:textColor="#000000"
 android:textSize="20sp"/>

 </LinearLayout>
        2
  •  0
  •   Misagh    9 年前 
    recyclerView = (RecyclerView) findViewById(R.id.recycler_view);
recyclerView.setHasFixedSize(true);
LinearLayoutManager layoutManager = new LinearLayoutManager(context);
layoutManager.setOrientation(LinearLayoutManager.VERTICAL);
recyclerView.setLayoutManager(layoutManager);
mAdapter = new MainAdapter(JsonData.rideList, MainActivity.this);
recyclerView.setAdapter(mAdapter);
mAdapter.notifyDataSetChanged();


    class MainAdapter extends android.support.v7.widget.RecyclerView.Adapter<MainAdapter.ViewHolder> {

        private ArrayList<Integer> rideList = new ArrayList<>();
        private Context context;

        public MainAdapter(ArrayList<Integer> rideList, Context context)
        {

    this.context = context;
      this.rideList = rideList;
    }

    @Override
    public MainAdapter.ViewHolder onCreateViewHolder(ViewGroup parent, int viewType)
    {
        View view = LayoutInflater.from(context).inflate(R.layout.row, parent, false);
        return new ViewHolder(view);
    }

    @Override
    public void onBindViewHolder(MainAdapter.ViewHolder holder, int position)
    {
        holder.rideHeight.setText(String.valueOf(rideList.get(position)));
    }

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

    public class ViewHolder extends RecyclerView.ViewHolder {

        public TextView rideHeight;
        public ViewHolder(View itemView) {
            super(itemView);

            rideHeight = (TextView) itemView.findViewById(R.id.rideHeight_textView);
        }
    }
    }

    row.xml 

    <?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical"
android:background="#ffffff"
android:padding="@dimen/activity_vertical_margin"
android:layout_width="match_parent"
android:layout_height="wrap_content">

<TextView
    android:id="@+id/rideHeight_textView"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:textColor="#000000"
    android:textSize="20sp"/>

</LinearLayout>
        3
  •  0
  •   M.Waqas Pervez    9 年前

    对于初学者来说,您没有在中调用数据获取程序方法 JsonData

    在适配器类中添加以下方法: 

    public void setList(ArrayList<Integer> rideList)
{
this.rideList = rideList;
notifyDataSetChanged();
}

    类别添加: 

    private MainAdapter adapter;

public JsonData(MainAdapter adapter)
{
this.adapter = adapter;
dropHeight.set("");
rideCount.set("");
}

    和改变 downloadFromSkistar 

    public void downloadFromSkistar()
{
if (SettingsActivity.submitClicked)
{
    eID = SettingsActivity.x;
    sID = SettingsActivity.y;
}
else
    {
        eID = 3206;
        sID = 11;
    }
 new AsyncTask<Void, Void, List<Integer>>() {

                            @Override
                            protected List<Integer> doInBackground(Void... voids) {

try
{

    URL url = new 
 URL("https://www.skistar.com/myskistar/api/v2/views/statisticspage.json?
 entityId=" + eID + "&seasonId=" + sID + " ");
    HttpURLConnection conn = (HttpURLConnection) url.openConnection();
    conn.setReadTimeout(10000 /* milliseconds */);
    conn.setConnectTimeout(15000 /* milliseconds */);
    conn.setRequestMethod("GET");
    // Starts the query
    conn.connect();

    int response = conn.getResponseCode();
    Log.i("AndroidExample", "Response: " + response);

    if (response == 200)
    {
        String json = getJson(conn.getInputStream());

        JSONObject jsonObject = new JSONObject(json);
        JSONArray jsonArray = jsonObject.getJSONArray("rideStatistics");

        int reponame = 0;
        int rHeight = 0;

        for (int i = 0; i < jsonArray.length(); i++)
        {
            JSONObject skiRun = jsonArray.getJSONObject(i);
            reponame += skiRun.getInt("height");

            rHeight += skiRun.getInt("height");
            rideList.add(new Integer(rHeight));
            rHeight = 0;
        }

    }
}
catch (Exception e)
{
    Log.i("AndroidExample", "Error");
}
finally
{
}

                                return rideList;
                            }

                            @Override
                            protected void onPostExecute(List<Integer> list) 
{
                                super.onPostExecute(list);
                                adapter.setList(rideList);
                            }
                        };

}

    最后终于改变了 MainActivity 收件人: 

    public class MainActivity extends AppCompatActivity {

private ActivityMainViewModel viewmodel;
RecyclerView recyclerView;
MainAdapter mAdapter;

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

ActivityMainBinding binding = DataBindingUtil.setContentView(this, R.layout.activity_main);

viewmodel = new ActivityMainViewModel();
binding.setViewmodel(viewmodel);

recyclerView = (RecyclerView) findViewById(R.id.recycler_view);
recyclerView.setHasFixedSize(true);
recyclerView.setLayoutManager(new LinearLayoutManager(this));
mAdapter = new MainAdapter(JsonData.rideList);

recyclerView.setAdapter(mAdapter);
new JsonData(mAdapter).downloadFromSkistar();
}

    NetworkOnMainThread AsyncTask

        4
  •  0
  •   random1234    9 年前

    下面是我解决这个问题的方法,顺便说一句,我也在使用SwipeRefreshLayout。 

    public class MainActivity extends AppCompatActivity {

private ActivityMainViewModel viewmodel;
RecyclerView recyclerView;
MainAdapter mAdapter;
public static ArrayList<Integer> rideList = new ArrayList<>();

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

    ActivityMainBinding binding = DataBindingUtil.setContentView(this, R.layout.activity_main);

    viewmodel = new ActivityMainViewModel();
    binding.setViewmodel(viewmodel);

    recyclerView = (RecyclerView) findViewById(R.id.recycler_view);
    recyclerView.setHasFixedSize(true);
    recyclerView.setLayoutManager(new LinearLayoutManager(this));
    mAdapter = new MainAdapter(rideList);
    recyclerView.setAdapter(mAdapter);

    viewmodel.jdDownloadFromSkistar();

    final SwipeRefreshLayout swipeRefreshLayout = (SwipeRefreshLayout) findViewById(R.id.swipelayout);;
    swipeRefreshLayout.setColorSchemeResources(R.color.refresh,R.color.refresh1,R.color.refresh2);

    swipeRefreshLayout.setOnRefreshListener(new SwipeRefreshLayout.OnRefreshListener() {
        @Override
        public void onRefresh() {

            swipeRefreshLayout.setRefreshing(true);

            refreshRecyclerView();

            swipeRefreshLayout.setRefreshing(false);
        }
    });
}

private void refreshRecyclerView()
{
    mAdapter.notifyDataSetChanged();
}

    我所做的就是调用jdDownloadFromSkistar();方法,当我滑动以刷新时,它使用notifyDataSetChanged()更新适配器;方法

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