Question

在这个问题中“RecyclerView: No Adapter attached; skipping layout” for recyclerview我抱怨说没有附加适配器;跳过布局＆＃34;使用RecyclerView时出错。部分是因为我没有得到解决这个问题的解决方案，我在Android Studio上疯狂了;在这个过程中，我打开了RecyclerView类，我发现该错误将显示的唯一条件是适配器为空时。我已经初始化并附加了适配器。我搜索并搜索了谷歌;没有解决方案。

我不明白，如果我移动初始化并附加到onCreate方法，应用程序会完全崩溃。

我现在的问题是：什么时候在RecyclerView中是一个适配器null，问题的解决方案可能是什么？

请帮助绿色开发者;这是我的第一个应用程序。任何建议都会受到欢迎。

MainActivity.java的这一部分

//Creating Views
    private RecyclerView recyclerView;
    private RecyclerView.Adapter adapter;
    private RecyclerView.LayoutManager layoutManager;

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

        //Initializing Views
        recyclerView = (RecyclerView) findViewById(R.id.post_recycler);
        layoutManager = new LinearLayoutManager(this);
        recyclerView.setLayoutManager(layoutManager);
        //Adding adapter to recyclerview
        recyclerView.setAdapter(adapter);

我也试过这个： 的 MainActivity.java

    //Creating Views
    private RecyclerView recyclerView;
    private RecyclerView.Adapter adapter;
    private RecyclerView.LayoutManager layoutManager;

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

        //Initializing Views
        recyclerView = (RecyclerView) findViewById(R.id.post_recycler);
        layoutManager = new LinearLayoutManager(this);
        recyclerView.setLayoutManager(layoutManager);

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

    //Initializing Views
    recyclerView = (RecyclerView) findViewById(R.id.post_recycler);
    layoutManager = new LinearLayoutManager(this);
    recyclerView.setLayoutManager(layoutManager);


    //Initializing the postlist list
    mPostItemsList = new ArrayList<>();

    //Caling method to get data
    getData();

//This method will get data from the web api
private void getData(){
    //Showing progress dialog
    final ProgressDialog progressDialog = ProgressDialog.show(this, "Loading posts", "Please wait", false, false);

    //Creating a json request
    JsonArrayRequest jsonArrayRequest = new JsonArrayRequest(ConfigPost.GET_URL,
            new Response.Listener<JSONArray>() {
                @Override
                public void onResponse(JSONArray response) {
                    //Dismissing the progress dialog
                    progressDialog.dismiss();

                    //calling method to parse json array
                    parseData(response);

                }
            },
            new Response.ErrorListener() {
                @Override
                public void onErrorResponse(VolleyError error) {

                }
            });

    //Creating request queue
    RequestQueue requestQueue = Volley.newRequestQueue(this);

    //Adding request to the queue
    requestQueue.add(jsonArrayRequest);
}

//This method will parse json data
private void parseData(JSONArray array){
    for(int i = 0; i<array.length(); i++) {
        PostItems postItem = new PostItems();
        JSONObject jsonObject = null;
        try {
            jsonObject = array.getJSONObject(i);
            postItem.setPost_image(jsonObject.getString(ConfigPost.TAG_POST_IMAGE));
            postItem.setPost_title(jsonObject.getString(ConfigPost.TAG_POST_TITLE));
            postItem.setPost_body(jsonObject.getString(ConfigPost.TAG_POST_BODY));
        } catch (JSONException w) {
            w.printStackTrace();
            //Toast.makeText(this, "Error in parsing Json", Toast.LENGTH_LONG).show();
        }
        mPostItemsList.add(postItem);
    }

    //Finally initialing the adapter
    adapter = new PostAdapter(mPostItemsList, this);

    //Adding adapter to recyclerview
    recyclerView.setAdapter(adapter);
    adapter.notifyDataSetChanged();
}

适配器类

public class PostAdapter extends RecyclerView.Adapter<PostAdapter.ViewHolder>{

    private ImageLoader mImageLoader;
    private Context mContext;

    //List of posts
    List<PostItems> mPostItems;



   public PostAdapter(List<PostItems> postItems, Context context) {
       super();

       //Getting all Posts
       this.mPostItems = postItems;
       this.mContext = context;
   }

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

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

      PostItems postList = mPostItems.get(position);

      mImageLoader = VolleyRequest.getInstance(mContext).getImageLoader();
      mImageLoader.get(postList.getPost_image(), ImageLoader.getImageListener(holder.postImage, R.mipmap.ic_launcher, android.R.drawable.ic_dialog_alert));

      holder.postImage.setImageUrl(postList.getPost_image(), mImageLoader);
      holder.postTitle.setText(postList.getPost_title());
      holder.postBody.setText(postList.getPost_body());

    }


    @Override
    public int getItemCount(){
        //Return the number of items in the data set
        return mPostItems.size();
    }

    class ViewHolder extends RecyclerView.ViewHolder {
        public NetworkImageView postImage;
        public TextView postTitle;
        public TextView postBody;

        public ViewHolder(View postView) {
            super(postView);
            postImage = (NetworkImageView) postView.findViewById(R.id.post_image);
            postTitle = (TextView) postView.findViewById(R.id.post_title);
            postBody = (TextView) postView.findViewById(R.id.post_body);
        }
    }
}

XML布局

<RelativeLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    app:layout_behavior="@string/appbar_scrolling_view_behavior"
    tools:context="com.jadebyte.geekng.MainActivity"
    tools:showIn="@layout/app_bar_main">

    <android.support.v7.widget.RecyclerView
        android:id="@+id/post_recycler"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:scrollbars="vertical"/>
</RelativeLayout>

Answer 1

您的问题是您在加载数据之前设置了适配器。 Volley在单独的线程中加载。

更改您的主要活动，如下所示。

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

//Initializing Views
recyclerView = (RecyclerView) findViewById(R.id.post_recycler);
layoutManager = new LinearLayoutManager(this);
recyclerView.setLayoutManager(layoutManager);


//Initializing the postlist list
mPostItemsList = new ArrayList<>();
adapter = new PostAdapter(mPostItemsList, this);

recyclerView.setAdapter(adapter);


//Caling method to get data
getData();

 //This method will get data from the web api
private void getData(){
//Showing progress dialog
final ProgressDialog progressDialog = ProgressDialog.show(this, "Loading posts", "Please wait", false, false);

//Creating a json request
JsonArrayRequest jsonArrayRequest = new JsonArrayRequest(ConfigPost.GET_URL,
        new Response.Listener<JSONArray>() {
            @Override
            public void onResponse(JSONArray response) {
                //Dismissing the progress dialog
                progressDialog.dismiss();

                //calling method to parse json array
                parseData(response);

            }
        },
        new Response.ErrorListener() {
            @Override
            public void onErrorResponse(VolleyError error) {

            }
         });

//Creating request queue
RequestQueue requestQueue = Volley.newRequestQueue(this);

//Adding request to the queue
requestQueue.add(jsonArrayRequest);
 }

 //This method will parse json data
private void parseData(JSONArray array){
for(int i = 0; i<array.length(); i++) {
    PostItems postItem = new PostItems();
    JSONObject jsonObject = null;
    try {
        jsonObject = array.getJSONObject(i);
        postItem.setPost_image(jsonObject.getString(ConfigPost.TAG_POST_IMAGE));
        postItem.setPost_title(jsonObject.getString(ConfigPost.TAG_POST_TITLE));
        postItem.setPost_body(jsonObject.getString(ConfigPost.TAG_POST_BODY));
    } catch (JSONException w) {
        w.printStackTrace();
        //Toast.makeText(this, "Error in parsing Json", Toast.LENGTH_LONG).show();
    }
    mPostItemsList.add(postItem);
  }
 adapter.notifyDatasetChanged();


}

Answer 2

无需调用adapter.notifyDataSetChanged()，因为您要使用整个列表设置适配器。或者您可以在layoutManager之后初始化适配器，然后更新它。

mPostItemList = new ArrayList<>();
adapter = new PostAdapter(mPostItemsList, this);

然后添加数据调用adapter.notifyDataSetChanged()

什么时候适配器在RecyclerView中为null

2 个答案: