Android 试图在recyclerview中获取json，但没有'；我不会成功的

以前我使用过ArrayAdapter和列表视图，所以我编写了这段代码来更新UI

private class UserAsync extends AsyncTask<String,Void,List<User>>{

    @Override
    protected List<User> doInBackground(String... urls) {

        if(urls.length <1 || urls[0] == null){
            return null;
        }

        List<User> result = null;
        try {
            result = QueryUtils.fetchJson(urls[0]);
        } catch (JSONException e) {
            Log.e(LOG_TAG,"Error in fetching json",e);
        }

        return result;
    }

    @Override
    protected void onPostExecute(List<User> users) {
        // Clear the adapter of previous earthquake data
        mAdapter.clear();

        // If there is a valid list of {@link user}s, then add them to the adapter's
        // data set. This will trigger the ListView to update.

        if(users != null && !users.isEmpty()){
            mAdapter.addAll(users);
            // After adding user to the adapter, Notify adapter for UI update
            mAdapter.notifyDataSetChanged();
        }
    }
}

items.xml

<android.support.constraint.ConstraintLayout 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"
    tools:context="examle.android.com.recyclerviewnetwork.MainActivity">

    <android.support.v7.widget.RecyclerView
        android:id="@+id/recyclerview"
        android:layout_width="match_parent"
        android:layout_height="match_parent">

    </android.support.v7.widget.RecyclerView>

</android.support.constraint.ConstraintLayout>

<android.support.v7.widget.CardView xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:id="@+id/card"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:elevation="8dp"
    app:cardCornerRadius="5dp"
    android:layout_marginTop="5dp"
    android:layout_marginLeft="5dp"
    android:layout_marginRight="5dp"
    android:padding="25dp">

        <LinearLayout

            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:orientation="horizontal">
        <ImageView
            android:id="@+id/avatar"
            android:layout_width="108dp"
            android:layout_height="108dp"
            android:padding="15dp"
            tools:src="@mipmap/ic_launcher" />
            <LinearLayout
                android:paddingRight="15dp"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:orientation="vertical">


            <TextView
                android:id="@+id/login"
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:paddingTop="15dp"
                tools:text="LOGIN_USER" />
            <TextView
                android:id="@+id/type"
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:paddingTop="3dp"
                tools:text="USER_TYPE" />
            </LinearLayout>
        </LinearLayout>
    </android.support.v7.widget.CardView>

更新代码：

在您的活动中：

public class MainActivity extends AppCompatActivity {
RecyclerView recyclerView;
UserAdapter mAdapter;
RecyclerView.LayoutManager layoutManager;
private static final String JSON_URL = "https://api.github.com/users";
private static final String LOG_TAG = MainActivity.class.getSimpleName();

public ArrayList users=new ArrayList（）

在异步任务中：

public class UserAsyncTask extends AsyncTask<String, Void, List<User>>{
    @Override
    protected List<User> doInBackground(String... urls) {

        if(urls.length < 1 || urls[0] == null ){
            return null;
        }


        try{
            users = QueryUtils.fetchJson(urls[0]);
        } catch (JSONException e) {
            Log.e(LOG_TAG,"Error in fetching json",e);
        }


        return result;
    }

    @Override
    protected void onPostExecute(List<User> users) {

        super.onPostExecute(users);

if(users != null && !users.isEmpty()){

        mAdapter.notifyDataSetChanged();
    }
    }
}

公共类UserAsyncTask扩展了AsyncTask{
@凌驾
受保护列表doInBackground（字符串…URL）{
if（url.length<1 | | url[0]==null）{
返回null；
}
试一试{
users=QueryUtils.fetchJson（URL[0]）；
}捕获（JSONException e）{
e（Log_标记，“获取json时出错”，e）；
}
返回结果；
}
@凌驾
受保护的void onPostExecute（列出用户）{
super.onPostExecute（用户）；
if（users！=null&！users.isEmpty（））{
mAdapter.notifyDataSetChanged（）；
}
}
}

---

或者使用与Listview相同的

onPostExecute

方法，并创建

mAdapter.addAll（用户）在recyclerview适配器中使用相同的方法。
在适配器中创建以下方法：

要清除您的数据：

public void clear() {
  int itemCount = getItemCount();
  users.clear();

  // notify your adapter that the data has been changed. You can also use notifyDataSetChanged() if you don't have an animation 
  if (itemCount > 0)
    notifyItemRangeRemoved(0, itemCount);
}

要将项目添加到适配器，请执行以下操作：

public void addAll(List<User> addUsers) {
  for (User user : addUsers) {
    users.add(l_user);

    // notify your adapter that the data has been changed. You can also use notifyDataSetChanged() if you don't have an animation.
    // If you use notifyDataSetChanged() you can call it on the outside of this loop just once
    notifyItemInserted(users.size());
  }
}

除非您尝试调试并找到问题的确切位置，否则发布异常代码不会对您有所帮助。@HemantParmar我想知道如何实现这两种异步任务方法我尝试使用mAdapter.addAll（users），但在addAll（）处显示错误method@shubhamkumar获取的错误是什么？请发布该错误无法解析方法“addAll”（java.util.ListError:（71，25）错误：找不到符号方法addAll（List）是否使用覆盖注释？
public class MainActivity extends AppCompatActivity {
RecyclerView recyclerView;
UserAdapter mAdapter;
RecyclerView.LayoutManager layoutManager;
private static final String JSON_URL = "https://api.github.com/users";
private static final String LOG_TAG = MainActivity.class.getSimpleName();

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


    recyclerView = (RecyclerView) findViewById(R.id.recyclerview);
    mAdapter = new UserAdapter(users,this);


    recyclerView.setLayoutManager(new LinearLayoutManager(this));
    recyclerView.setAdapter(mAdapter);

    UserAsyncTask task = new UserAsyncTask();
    task.execute(JSON_URL);


}

public class UserAsyncTask extends AsyncTask<String, Void, List<User>>{
    @Override
    protected List<User> doInBackground(String... urls) {

        if(urls.length < 1 || urls[0] == null ){
            return null;
        }


        try{
            users = QueryUtils.fetchJson(urls[0]);
        } catch (JSONException e) {
            Log.e(LOG_TAG,"Error in fetching json",e);
        }


        return result;
    }

    @Override
    protected void onPostExecute(List<User> users) {

        super.onPostExecute(users);

if(users != null && !users.isEmpty()){

        mAdapter.notifyDataSetChanged();
    }
    }
}

public void clear() {
  int itemCount = getItemCount();
  users.clear();

  // notify your adapter that the data has been changed. You can also use notifyDataSetChanged() if you don't have an animation 
  if (itemCount > 0)
    notifyItemRangeRemoved(0, itemCount);
}

public void addAll(List<User> addUsers) {
  for (User user : addUsers) {
    users.add(l_user);

    // notify your adapter that the data has been changed. You can also use notifyDataSetChanged() if you don't have an animation.
    // If you use notifyDataSetChanged() you can call it on the outside of this loop just once
    notifyItemInserted(users.size());
  }
}

@Override
protected void onPostExecute(List<User> users) {
  // clear the previous data
  mAdapter.clear();

  // add the new data
  if(users != null)
    mAdapter.addAll(users);
}