嵌套内部片段无法将适配器设置为 recyclerView答案

【问题标题】：Nested inner fragment not able to set adapter to recyclerView嵌套内部片段无法将适配器设置为 recyclerView
【发布时间】：2017-09-09 14:41:36
【问题描述】：

我制作了一个应用程序，其中有一个带有导航抽屉的主要活动。在其中一个片段（即 SourceFragment）中，我在顶部创建了一个 tabview，在选项卡下方创建了一个视图寻呼机，其中 2 个片段（即 AllSourcesFragment 和 PreferredSourcesFragment）被夸大了。我可以在 AllSourcesFragment 中设置一个微调器并实现它。但我想在微调卡下方设置一个 recyclerView（带卡）。我可以为 recyclerView 设置 layoutInflater，即当我在 AllSourcesFragment.java 中注释掉行 a 时，该应用程序可以在所有组件正常工作的情况下顺利运行。但是当我执行 a 行时，会出现以下错误

04-13 15:22:22.171 2662-2662/? E/WindowManager: android.view.WindowLeaked: Activity com.example.kartik.bulletin.MainActivity has leaked window DecorView@bbc06ec[Please wait] 原来是在这里添加的在 android.view.ViewRootImpl.(ViewRootImpl.java:424) 在 android.view.WindowManagerGlobal.addView(WindowManagerGlobal.java:331) 在 android.view.WindowManagerImpl.addView(WindowManagerImpl.java:93) 在 android.app.Dialog.show(Dialog.java:316) 在 com.example.kartik.bulletin.Downloader.onPreExecute(Downloader.java:49) 在 android.os.AsyncTask.executeOnExecutor(AsyncTask.java:613) 在 android.os.AsyncTask.execute(AsyncTask.java:560) 在 com.example.kartik.bulletin.AllSourcesFragment.onCreateView(AllSourcesFragment.java:42) 在 android.support.v4.app.Fragment.performCreateView(Fragment.java:2192) 在 android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1299) 在 android.support.v4.app.FragmentManagerImpl.moveFragmentToExpectedState(FragmentManager.java:1528) 在 android.support.v4.app.FragmentManagerImpl.moveToState(FragmentManager.java:1595) 在 android.support.v4.app.BackStackRecord.executeOps(BackStackRecord.java:758) 在 android.support.v4.app.FragmentManagerImpl.executeOps(FragmentManager.java:2363) 在 android.support.v4.app.FragmentManagerImpl.executeOpsTogether(FragmentManager.java:2149) 在 android.support.v4.app.FragmentManagerImpl.optimizeAndExecuteOps(FragmentManager.java:2103) 在 android.support.v4.app.FragmentManagerImpl.execSingleAction(FragmentManager.java:1984) 在 android.support.v4.app.BackStackRecord.commitNowAllowingStateLoss(BackStackRecord.java:626) 在 android.support.v4.app.FragmentPagerAdapter.finishUpdate(FragmentPagerAdapter.java:143) 在 android.support.v4.view.ViewPager.populate(ViewPager.java:1268) 在 android.support.v4.view.ViewPager.populate(ViewPager.java:1116) 在 android.support.v4.view.ViewPager.onMeasure(ViewPager.java:1642) 在 android.view.View.measure(View.java:19756) 在 android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:6124) 在 android.widget.LinearLayout.measureChildBeforeLayout(LinearLayout.java:1464) 在 android.widget.LinearLayout.measureVertical(LinearLayout.java:758) 在 android.widget.LinearLayout.onMeasure(LinearLayout.java:640) 在 android.view.View.measure(View.java:19756) 在 android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:6124) 在 android.widget.FrameLayout.onMeasure(FrameLayout.java:185) 在 android.view.View.measure(View.java:19756) 在 android.support.v4.widget.DrawerLayout.onMeasure(DrawerLayout.java:1081) 在 android.view.View.measure(View.java:19756) 在 android.widget.RelativeLayout.measureChildHorizontal(RelativeLayout.java:715) 在 android.widget.RelativeLayout.onMeasure(RelativeLayout.java:461) 在 android.view.View.measure(View.java:19756) 在 android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:6124) 在 android.widget.FrameLayout.onMeasure(FrameLayout.java:185) 在 android.support.v7.widget.ContentFrameLayout.onMeasure(ContentFrameLayout.java:139) 在 android.view.View.measure(View.java:19756) 在 android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:6124) 在 android.support.v7.widget.ActionBarOverlayLayout.onMeasure(ActionBarOverlayLayout.java:393) 在 android.view.View.measure(View.java:19756) 在 android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:6124) 在 android.widget.FrameLayout.onMeasure(FrameLayout.java:185) 在 android.view.View.measure(View.java:19756) 在 android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:6124) 在 android.widget.LinearLayout.measureChildBeforeLayout(LinearLayout.java:1464) 在 android.widget.LinearLayout.measureVertical(LinearLayout.java:758) 在 android.widget.LinearLayout.onMeasure(LinearLayout.java:640) 在 android.view.View.measure(View.java:19756) 在 android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:6124) 在 android.widget.FrameLayout.onMeasure(FrameLayout.java:185) 在 com.android.internal.policy.DecorView.onMeasure(DecorView.java:687) 04-13 15:22:22.171 2662-2662/? E/WindowManager：在 android.view.View.measure(View.java:19756) 在 android.view.ViewRootImpl.performMeasure(ViewRootImpl.java:2283) 在 android.view.ViewRootImpl.measureHierarchy（ViewRootImpl.java:1370）在 android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:1619) 在 android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:1258) 在 android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:6348) 在 android.view.Choreographer$CallbackRecord.run(Choreographer.java:871) 在 android.view.Choreographer.doCallbacks(Choreographer.java:683) 在 android.view.Choreographer.doFrame(Choreographer.java:619) 在 android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:857) 在 android.os.Handler.handleCallback(Handler.java:751) 在 android.os.Handler.dispatchMessage(Handler.java:95) 在 android.os.Looper.loop(Looper.java:154) 在 android.app.ActivityThread.main(ActivityThread.java:6123) 在 java.lang.reflect.Method.invoke（本机方法）在 com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:867) 在 com.android.internal.os.ZygoteInit.main(ZygoteInit.java:757)

AllSourcesFragment.java

package com.example.kartik.bulletin;


import android.content.Context;
import android.os.Bundle;
import android.os.RecoverySystem;
import android.support.v4.app.Fragment;
import android.support.v7.widget.LinearLayoutManager;
import android.support.v7.widget.RecyclerView;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ArrayAdapter;
import android.widget.Spinner;

public class AllSourcesFragment extends Fragment {


    Spinner categorySpinner;
    String url = "https://newsapi.org/v1/sources";

    public AllSourcesFragment() {
        // Required empty public constructor
    }
    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        // Inflate the layout for this fragment
        View view = inflater.inflate(R.layout.fragment_all_sources, container, false);



        categorySpinner = (Spinner)view.findViewById(R.id.source_categoryspinner);
        final String[] categories = new String[] { "All categories", "general", "business", "entertainment", "gaming", "music", "science-and-nature", "sport", "technology"};
        ArrayAdapter<String> arrayAdapter = new ArrayAdapter<String>(getContext(), android.R.layout.simple_spinner_item, categories);
        categorySpinner.setAdapter(arrayAdapter);


        RecyclerView recyclerView = (RecyclerView)view.findViewById(R.id.source_recyclerview);
        recyclerView.setLayoutManager(new LinearLayoutManager(getContext()));

//Line a that is creating problem 
        new Downloader(getContext(), url, recyclerView, 0, "All Sources").execute();

        return  view;
    }

}

Downloader.java

package com.example.kartik.bulletin;

import android.app.ProgressDialog;
import android.content.Context;
import android.os.AsyncTask;
import android.support.v7.widget.RecyclerView;
import android.util.Log;
import android.widget.Toast;

import java.io.BufferedInputStream;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.net.HttpURLConnection;

/**
 * Created by kartik on 13/4/17.
 */

public class Downloader extends AsyncTask<Void, Void, String> {



    Context c;
    String jsonUrl, category;
    RecyclerView rv;
    int choice;

    String TAG = "Bla bla";
    ProgressDialog pd;

    public Downloader(Context c, String jsonUrl, RecyclerView rv, int choice, String category) {
        this.c = c;
        this.jsonUrl = jsonUrl;
        this.rv = rv;
        this.choice = choice;
        this.category = category;
    }


    @Override
    protected void onPreExecute() {
        super.onPreExecute();

        pd = new ProgressDialog(c);
        pd.setTitle("Please wait...");
        pd.setMessage("Loading list of news sources");
        pd.show();
    }


    @Override
    protected String doInBackground(Void... params) {
        return download();
    }

    @Override
    protected void onPostExecute(String jsonData) {
        super.onPostExecute(jsonData);

        pd.dismiss();
        if(jsonData.startsWith("Error")){
            String error = jsonData;
            Toast.makeText(c, error, Toast.LENGTH_SHORT).show();
        }else {
            //parser
            if(choice == 0)
                new SourceParser(c, jsonData, rv, category).execute();
            /*else
                new NewsParser(c, jsonData, rv).execute();*/
        }
    }

    private String download(){
        Object connection = Connector.connect(jsonUrl);
        if(connection.toString().startsWith("Error"))
            return connection.toString();

        try{
            HttpURLConnection con = (HttpURLConnection)connection;
            if(con.getResponseCode()==con.HTTP_OK){
                InputStream is = new BufferedInputStream(con.getInputStream());
                BufferedReader br = new BufferedReader(new InputStreamReader(is));

                String line;
                StringBuffer jsonData = new StringBuffer();

                while((line = br.readLine())!=null)
                    jsonData.append(line+"\n");

                br.close();
                is.close();

                Log.d(TAG, jsonData.toString());
                return jsonData.toString();

            }else {
                return "Error" + con.getResponseMessage();
            }
        } catch (IOException e) {
            e.printStackTrace();
            return "Error : "+e.getMessage();
        }
    }
}

SourceParser.java

package com.example.kartik.bulletin;

import android.app.ProgressDialog;
import android.content.Context;
import android.os.AsyncTask;
import android.support.v7.widget.RecyclerView;
import android.util.Log;
import android.widget.Toast;

import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;

import java.util.ArrayList;

/**
 * Created by kartik on 13/4/17.
 */

public class SourceParser extends AsyncTask<Void, Void, Boolean> {

    Context c;
    String jsonData, category;
    RecyclerView rv;
    String TAG = "NOT bla bla";
    SourceAdapter adapter;

    ProgressDialog pd;
    ArrayList<SourceItem> sourceItems= new ArrayList<>();

    public SourceParser(Context c, String jsonData, RecyclerView rv, String category) {
        this.c = c;
        this.jsonData = jsonData;
        this.rv = rv;
        this.category = category;
    }

    @Override
    protected void onPreExecute() {
        super.onPreExecute();
        Log.d(TAG, "onPreExecute: parser reached");

        pd = new ProgressDialog(c);
        pd.setTitle("Please wait...");
        pd.setMessage("Loading list of news sourceItems");
        pd.show();
    }

    @Override
    protected Boolean doInBackground(Void... params) {
        Log.d(TAG, "doInBackground: parser reached");
        return parse();
    }

    @Override
    protected void onPostExecute(Boolean isParsed) {
        super.onPostExecute(isParsed);
        Log.d(TAG, "onPosExecute: parser reached");
        pd.dismiss();

        if(isParsed){
            adapter = new SourceAdapter(c, sourceItems);
            rv.setAdapter(adapter);
        }else
            Toast.makeText(c, "Unable to parse", Toast.LENGTH_LONG).show();


    }


    private boolean parse(){
        try{
            sourceItems.clear();
            JSONObject obj = new JSONObject(jsonData);
            JSONArray jsonArray = obj.getJSONArray("sources");
            for(int i=0; i<jsonArray.length(); i++){

                JSONObject jsonObject = (JSONObject) jsonArray.get(i);

                if(!category.equals("All categories") && !category.equals(jsonObject.getString("category")))
                    continue;


                Log.d(TAG, jsonObject.getString("name"));

                String id = jsonObject.getString("id");
                String name = jsonObject.getString("name");
                String description = jsonObject.getString("description");
                String actualUrl= jsonObject.getString("url");
                String category= jsonObject.getString("category");
                String language= jsonObject.getString("language");
                String country= jsonObject.getString("country");

                Log.d(TAG, jsonObject.getString("id"));
                JSONObject urls = jsonObject.getJSONObject("urlsToLogos");

                String surl= urls.getString("small");
                String murl= urls.getString("medium");
                String lurl= urls.getString("large");

                sourceItems.add(new SourceItem(id, name, description, actualUrl, category, language, country, surl, murl, lurl));

                String a = Integer.toString(sourceItems.size());
                Log.d(TAG, a);


            }


            return true;
        } catch (JSONException e) {
            e.printStackTrace();
            return false;
        }
    }
}

SourceAdapter.java

package com.example.kartik.bulletin;

import android.content.Context;
import android.content.Intent;
import android.support.v7.widget.CardView;
import android.support.v7.widget.RecyclerView;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ImageView;
import android.widget.ProgressBar;
import android.widget.TextView;
import android.widget.Toast;

import com.bumptech.glide.Glide;
import com.bumptech.glide.load.resource.drawable.GlideDrawable;
import com.bumptech.glide.request.RequestListener;
import com.bumptech.glide.request.target.Target;

import java.util.List;

/**
 * Created by kartik on 13/4/17.
 */

public class SourceAdapter extends RecyclerView.Adapter<SourceAdapter.SourceViewHolder> {


    private List<SourceItem> sources;
    private Context context;
    private LayoutInflater inflater;


    public SourceAdapter(Context context, List<SourceItem> sources) {
        this.sources = sources;
        this.context = context;
        inflater = (LayoutInflater) context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
    }

    public class SourceViewHolder extends RecyclerView.ViewHolder {

        ImageView imageView;
        TextView title, description, category;
        ProgressBar progressBar;
        CardView cardView;
        public SourceViewHolder(View itemView) {
            super(itemView);


            imageView = (ImageView)itemView.findViewById(R.id.source_imageview);
            title = (TextView)itemView.findViewById(R.id.source_title);
            description = (TextView)itemView.findViewById(R.id.source_description);
            category = (TextView)itemView.findViewById(R.id.source_category);
            progressBar = (ProgressBar)itemView.findViewById(R.id.source_progressbar);
            cardView = (CardView)itemView.findViewById(R.id.source_card);


        }

    }





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


        View rootView = inflater.inflate(R.layout.card_source, parent, false);
        return new SourceViewHolder(rootView);
    }

    @Override
    public void onBindViewHolder(final SourceViewHolder holder, int position) {
        final SourceItem item = sources.get(position);

        String cat = "Category : "+item.getCategory();
        holder.title.setText(item.getName());
        holder.description.setText(item.getDescription());
        holder.category.setText(cat);

        Glide.with(context)
                .load(item.getLargeLogoUrl())
                .listener(new RequestListener<String, GlideDrawable>() {
                    @Override
                    public boolean onException(Exception e, String model, Target<GlideDrawable> target, boolean isFirstResource) {
                        holder.progressBar.setVisibility(View.GONE);
                        return false;
                    }

                    @Override
                    public boolean onResourceReady(GlideDrawable resource, String model, Target<GlideDrawable> target, boolean isFromMemoryCache, boolean isFirstResource) {
                        holder.progressBar.setVisibility(View.GONE);
                        return false;
                    }
                })
                //.error(R.drawable.image_not_found)
                .into(holder.imageView);


        holder.cardView.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                clicked(item);
            }
        });
    }

    private void clicked(SourceItem item) {
        Toast.makeText(context, "Click on any article to read it!", Toast.LENGTH_LONG).show();
        /*Intent intent = new Intent(context, NewsActivity.class);
        intent.putExtra("id", item.getId());
        intent.putExtra("name", item.getName());
        context.startActivity(intent);*/
    }

    @Override
    public int getItemCount() {
        if(sources == null)
            return 0;
        return sources.size();
    }


}

SourceFragment.java

package com.example.kartik.bulletin;

import android.os.Bundle;
import android.support.design.widget.TabLayout;
import android.support.v4.app.Fragment;
import android.support.v4.view.ViewPager;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;

public class SourceFragment extends Fragment {
    public  static TabLayout tabLayout;
    public  static ViewPager viewPager;
    public  static int int_items= 2;


    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        // Inflate the layout for this fragment
        View view =  inflater.inflate(R.layout.fragment_source, null);

        tabLayout=(TabLayout)view.findViewById(R.id.tabs);
        viewPager=(ViewPager)view.findViewById(R.id.viewpager);
        //set an adpater


        viewPager.setAdapter(new MyAdapter(getChildFragmentManager()))  ;

        tabLayout.post(new Runnable() {
            @Override
            public void run() {
                tabLayout.setupWithViewPager(viewPager);
            }
        });

        return view;
    }
}

MainActivity.java

package com.example.kartik.bulletin;

import android.support.annotation.NonNull;
import android.support.design.widget.NavigationView;
import android.support.v4.app.FragmentManager;
import android.support.v4.app.FragmentTransaction;
import android.support.v4.widget.DrawerLayout;
import android.support.v7.app.ActionBarDrawerToggle;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.support.v7.widget.Toolbar;
import android.view.MenuItem;

public class MainActivity extends AppCompatActivity {

    DrawerLayout drawerLayout;
    NavigationView navigationView;
    FragmentManager FM;
    FragmentTransaction FT;



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


        drawerLayout = (DrawerLayout) findViewById(R.id.drawerLayout);
        navigationView= (NavigationView) findViewById(R.id.shitstuff);

        FM= getSupportFragmentManager();
        FT= FM.beginTransaction();
        FT.replace(R.id.containerView, new SourceFragment()).commit();

        navigationView.setNavigationItemSelectedListener(new NavigationView.OnNavigationItemSelectedListener() {
            @Override
            public boolean onNavigationItemSelected(@NonNull MenuItem item) {
                drawerLayout.closeDrawers();

                if (item.getItemId()== R.id.nav_articles) {
                    FragmentTransaction fragmentTransaction= FM.beginTransaction();
                    fragmentTransaction.replace(R.id.containerView, new ArticleFragment()).commit();
                }
                if(item.getItemId()==R.id.nav_sources){
                    FragmentTransaction fragmentTransaction1=FM.beginTransaction();
                    fragmentTransaction1.replace(R.id.containerView,new SourceFragment()).commit();
                }
                if(item.getItemId()==R.id.nav_bookmarks){
                    FragmentTransaction fragmentTransaction1=FM.beginTransaction();
                    fragmentTransaction1.replace(R.id.containerView,new BookmarkFragment()).commit();
                }
                return false;
            }
        });


        android.support.v7.widget.Toolbar toolbar = (Toolbar)findViewById(R.id.toolbar);
        ActionBarDrawerToggle toggle= new ActionBarDrawerToggle(this,drawerLayout,toolbar,R.string.app_name,R.string.app_name);
        drawerLayout.addDrawerListener(toggle);
        toggle.syncState();
    }
}

我没有展示其他类，但是我在一个单独的项目中使用了相同的布局，并且该应用程序运行良好（在该应用程序中，我只是放置了一个活动，并且它暗示了一个片段 > AllSourcesFragment。我是新人到android并且无法对这个主题进行很好的研究。我哪里错了？

【问题讨论】：

下次代码会少很多

标签： java android android-fragments android-recyclerview

【解决方案1】：

该错误通常意味着在销毁活动时对话框处于打开状态。

要么

a) 在异步操作的 Downloader 在 ProgressDialog 上的 dismiss() 上调用 dismiss() 或 PostExecute 之前，您的片段实际上已被销毁或

b) 一个不相关的错误（可能在您的doInBackground 中的download() 调用中）导致PostExecute 永远不会被调用。

在后一种情况下，您应该早一点在日志文件中看到潜在错误。

另见this question。

【讨论】：