android - 错误 : The specified child already has a parent. 您必须先在 child 的 parent 上调用 removeView()

Question

不明白哪里出了问题，第二天脑袋都碎了...

我想将 TabLayout 与 2 个选项卡一起使用，其中第一个 RecyclerView 与 ArtistModel，但是当我用 RecyclerView 给 Fragment 充气时，会出现这个错误。

这是我的代码。 fragment

package com.shagi.yandex.lookart.fragment;    

import android.app.Fragment;
import android.os.Bundle;

import android.support.v7.widget.LinearLayoutManager;
import android.support.v7.widget.RecyclerView;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;

import com.shagi.yandex.lookart.JsonHelper;
import com.shagi.yandex.lookart.MainActivity;
import com.shagi.yandex.lookart.R;
import com.shagi.yandex.lookart.adaptor.ArtistsAdapter;
import com.shagi.yandex.lookart.pojo.Artist;

import java.util.List;
import java.util.concurrent.ExecutionException;    

/**
 * A simple {@link Fragment} subclass.
 */
public class ArtistsFragment extends Fragment {

    private RecyclerView rvArtists;
    private RecyclerView.LayoutManager layoutManager;

    private ArtistsAdapter adapter;

    private List<Artist> artists;

    public MainActivity activity;

    public ArtistsFragment() {
        // Required empty public constructor
    }

    @Override
    public void onActivityCreated(Bundle savedInstanceState) {
        super.onActivityCreated(savedInstanceState);
        if (getActivity() != null) {
            activity = (MainActivity) getActivity();
        }
        loadArtistModels();
    }

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {

        View rootView = inflater.inflate(R.layout.fragment_artists, container, false);

        rvArtists = (RecyclerView) rootView.findViewById(R.id.rvArtists);

        layoutManager = new LinearLayoutManager(getActivity());

        rvArtists.setLayoutManager(layoutManager);
        artists = loadArtistModels();

        adapter = new ArtistsAdapter(artists);

        rvArtists.setAdapter(adapter);

        // Inflate the layout for this fragment
        return rootView;
    }

    private List<Artist> loadArtistModels() {
        try {
            return new JsonHelper().execute().get();
        } catch (InterruptedException e) {
            e.printStackTrace();
        } catch (ExecutionException e) {
            e.printStackTrace();
        }
        return null;
    }
}

适配器

package com.shagi.yandex.lookart.adaptor;

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.TextView;

import com.shagi.yandex.lookart.DownloadImageTask;
import com.shagi.yandex.lookart.R;
import com.shagi.yandex.lookart.pojo.Artist;

import java.util.List;

/**
 * Created by Shagi on 06.04.2016.
 */
public class ArtistsAdapter extends RecyclerView.Adapter<ArtistsAdapter.ViewHolder> {

    List<Artist> artists;

    public ArtistsAdapter(List<Artist> artists) {
        this.artists = artists;
    }

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

        View v = LayoutInflater.from(parent.getContext()).inflate(R.layout.model_artist, parent, false);

        ImageView smallCover = (ImageView) v.findViewById(R.id.small_cover);
        TextView name = (TextView) v.findViewById(R.id.tvArtistName);
        TextView style = (TextView) v.findViewById(R.id.tvStyle);
        TextView albums = (TextView) v.findViewById(R.id.tvAlbums);

        return new ViewHolder(parent, smallCover, name, style, albums);
    }

    @Override
    public void onBindViewHolder(ViewHolder holder, int position) {
        // - get element from your dataset at this position
        // - replace the contents of the view with that element
        Artist artist = artists.get(position);
        new DownloadImageTask(holder.smallCover).execute(artist.getCover().getSmall());
        holder.artistName.setText(artist.getName());
        String style = "";
        for (String string : artist.getGenres()) {
            style += string + " ";
        }
        holder.artistStyle.setText(style);
        String albums = "альбомов " + artist.getAlbums() + ", треков " + artist.getTracks();
        holder.artistAlbums.setText(albums);
    }

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

    public static class ViewHolder extends RecyclerView.ViewHolder {
        // each data item is just a string in this case
        public ImageView smallCover;
        public TextView artistName;
        public TextView artistStyle;
        public TextView artistAlbums;

        public ViewHolder(View v, ImageView img, TextView artistName, TextView artistStyle, TextView artistAlbums) {
            super(v);
            smallCover = img;
            this.artistName = artistName;
            this.artistStyle = artistStyle;
            this.artistAlbums = artistAlbums;
        }
    }
}

和MainActivity

package com.shagi.yandex.lookart;

import android.app.FragmentManager;
import android.os.Bundle;
import android.support.design.widget.TabLayout;
import android.support.v4.content.ContextCompat;
import android.support.v4.view.ViewPager;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.Toolbar;    
import android.view.Menu;
import android.view.MenuItem;    
import com.shagi.yandex.lookart.adaptor.TabAdaptor;
import com.shagi.yandex.lookart.fragment.SplashFragment;

public class MainActivity extends AppCompatActivity {

    FragmentManager fragmentManager;
    PreferenceHelper preferenceHelper;
    TabAdaptor tabAdaptor;

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

        PreferenceHelper.getInstance().init(getApplicationContext());
        preferenceHelper = PreferenceHelper.getInstance();
        fragmentManager = getFragmentManager();


        //runSplash();
        setUI();
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.menu_main, menu);
        MenuItem splashItem = menu.findItem(R.id.action_splash);
        splashItem.setChecked(preferenceHelper.getBoolean(PreferenceHelper.SPLASH_IS_INVISIBLE));
        return true;
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        // Handle action bar item clicks here. The action bar will
        // automatically handle clicks on the Home/Up button, so long
        // as you specify a parent activity in AndroidManifest.xml.
        int id = item.getItemId();

        //noinspection SimplifiableIfStatement
        if (id == R.id.action_splash) {
            item.setChecked(!item.isChecked());
            preferenceHelper.putBoolean(PreferenceHelper.SPLASH_IS_INVISIBLE, item.isChecked());
            return true;
        }

        return super.onOptionsItemSelected(item);
    }

    public void runSplash() {
        if (!preferenceHelper.getBoolean(PreferenceHelper.SPLASH_IS_INVISIBLE)) {
            SplashFragment splashFragment = new SplashFragment();
            fragmentManager.beginTransaction()
                    .replace(R.id.content_frame, splashFragment).addToBackStack(null).commit();
        }
    }

    public void setUI() {
        Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
        if (toolbar != null) {
            toolbar.setTitleTextColor(ContextCompat.getColor(getApplicationContext(), R.color.white));
            setSupportActionBar(toolbar);
        }

        TabLayout tabLayout = (TabLayout) findViewById(R.id.tab_layout);
        tabLayout.addTab(tabLayout.newTab().setText(R.string.artists_tab));
        tabLayout.addTab(tabLayout.newTab().setText(R.string.selected_artist_tab));

        final ViewPager viewPager = (ViewPager) findViewById(R.id.pager);
        tabAdaptor = new TabAdaptor(fragmentManager, 2);

        viewPager.setAdapter(tabAdaptor);
        viewPager.addOnPageChangeListener(new TabLayout.TabLayoutOnPageChangeListener(tabLayout));

        tabLayout.setOnTabSelectedListener(new TabLayout.OnTabSelectedListener() {
            @Override
            public void onTabSelected(TabLayout.Tab tab) {
                viewPager.setCurrentItem(tab.getPosition());
            }

            @Override
            public void onTabUnselected(TabLayout.Tab tab) {

            }

            @Override
            public void onTabReselected(TabLayout.Tab tab) {

            }
        });    
    }    
}

堆栈跟踪按要求

java.lang.IllegalStateException: The specified child already has a parent. You must call removeView() on the child's parent first.
    at android.view.ViewGroup.addViewInner(ViewGroup.java:4066)
    at android.view.ViewGroup.addView(ViewGroup.java:3916)
    at android.view.ViewGroup.addView(ViewGroup.java:3857)
    at android.support.v7.widget.RecyclerView$5.addView(RecyclerView.java:585)
    at android.support.v7.widget.ChildHelper.addView(ChildHelper.java:107)
    at android.support.v7.widget.RecyclerView$LayoutManager.addViewInt(RecyclerView.java:6249)
    at android.support.v7.widget.RecyclerView$LayoutManager.addView(RecyclerView.java:6207)
    at android.support.v7.widget.RecyclerView$LayoutManager.addView(RecyclerView.java:6195)
    at android.support.v7.widget.LinearLayoutManager.layoutChunk(LinearLayoutManager.java:1384)
    at android.support.v7.widget.LinearLayoutManager.fill(LinearLayoutManager.java:1333)
    at android.support.v7.widget.LinearLayoutManager.onLayoutChildren(LinearLayoutManager.java:562)
    at android.support.v7.widget.RecyclerView.dispatchLayout(RecyclerView.java:2900)
    at android.support.v7.widget.RecyclerView.onLayout(RecyclerView.java:3071)
    at android.view.View.layout(View.java:16001)
    at android.view.ViewGroup.layout(ViewGroup.java:5181)
    at android.widget.FrameLayout.layoutChildren(FrameLayout.java:639)
    at android.widget.FrameLayout.onLayout(FrameLayout.java:574)
    at android.view.View.layout(View.java:16001)
    at android.view.ViewGroup.layout(ViewGroup.java:5181)
    at android.support.v4.view.ViewPager.onLayout(ViewPager.java:1627)
    at android.view.View.layout(View.java:16001)
    at android.view.ViewGroup.layout(ViewGroup.java:5181)
    at android.support.design.widget.CoordinatorLayout.layoutChild(CoordinatorLayout.java:1037)
    at android.support.design.widget.CoordinatorLayout.onLayoutChild(CoordinatorLayout.java:747)
    at android.support.design.widget.ViewOffsetBehavior.onLayoutChild(ViewOffsetBehavior.java:42)
    at android.support.design.widget.AppBarLayout$ScrollingViewBehavior.onLayoutChild(AppBarLayout.java:1133)
    at android.support.design.widget.CoordinatorLayout.onLayout(CoordinatorLayout.java:760)
    at android.view.View.layout(View.java:16001)
    at android.view.ViewGroup.layout(ViewGroup.java:5181)
    at android.widget.FrameLayout.layoutChildren(FrameLayout.java:639)
    at android.widget.FrameLayout.onLayout(FrameLayout.java:574)
    at android.view.View.layout(View.java:16001)
    at android.view.ViewGroup.layout(ViewGroup.java:5181)
    at android.widget.FrameLayout.layoutChildren(FrameLayout.java:639)
    at android.widget.FrameLayout.onLayout(FrameLayout.java:574)
    at android.view.View.layout(View.java:16001)
    at android.view.ViewGroup.layout(ViewGroup.java:5181)
    at android.widget.LinearLayout.setChildFrame(LinearLayout.java:1959)
    at android.widget.LinearLayout.layoutVertical(LinearLayout.java:1813)
    at android.widget.LinearLayout.onLayout(LinearLayout.java:1722)
    at android.view.View.layout(View.java:16001)
    at android.view.ViewGroup.layout(ViewGroup.java:5181)
    at android.widget.FrameLayout.layoutChildren(FrameLayout.java:639)
    at android.widget.FrameLayout.onLayout(FrameLayout.java:574)
    at android.view.View.layout(View.java:16001)
    at android.view.ViewGroup.layout(ViewGroup.java:5181)
    at android.widget.LinearLayout.setChildFrame(LinearLayout.java:1959)
    at android.widget.LinearLayout.layoutVertical(LinearLayout.java:1813)
    at android.widget.LinearLayout.onLayout(LinearLayout.java:1722)
    at android.view.View.layout(View.java:16001)
    at android.view.ViewGroup.layout(ViewGroup.java:5181)
    at android.widget.FrameLayout.layoutChildren(FrameLayout.java:639)
    at android.widget.FrameLayout.onLayout(FrameLayout.java:574)
    at android.view.View.layout(View.java:16001)
    at android.view.ViewGroup.layout(ViewGroup.java:5181)
    at android.view.ViewRootImpl.performLayout(ViewRootImpl.java:2467)
    at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:2164)
    at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:1282)
    at android.

如有不明白之处，请追问。看来我自己解决不了。

Answer 1

您应该在 onCreateView() 方法中将 View v 而不是 parent 传递给 ViewHolder。此外，最好使用 initialise Views 在 Viewholder 中，而不是在 onCreateView()

中

View v = LayoutInflater.from(parent.getContext()).inflate(R.layout.model_artist, parent, false);

更新这一行

return new ViewHolder(parent, smallCover, name, style, albums);

到

return new ViewHolder(v, smallCover, name, style, albums);