Material 容器变换动画在 Java 中不起作用

Question

我正在尝试按照此 post MaterialContainerTransform transition is not Working on Return 所述在 Recyclerview 适配器中使用 Material 容器转换，但在我的项目中实施此操作后，我收到空指针异常错误。众所周知 Material Container Transform 动画教程在 kotlin 中，我在 java 中进行。因此，如果有人知道如何在 recyclerview 中正确使用 material 容器变换动画并指出我的错误，我将非常感谢他。

RecyclerView 适配器Class（来源）

public class RecyclerViewAdapter extends RecyclerView.Adapter<RecyclerViewAdapter.ViewHolder> implements Filterable {


    private Context context;
    private List<Astadhyayi> wordList;
    private List<Astadhyayi> filwordList;
    private DictionaryDB dictionaryDB;

    private OnclickListenerInterface listener;



    public RecyclerViewAdapter(Context context, List<Astadhyayi> itemList, DictionaryDB dictionaryDB) {

        this.context = context;
        this.wordList = itemList;
        this.dictionaryDB = dictionaryDB;
        filwordList = new ArrayList<Astadhyayi>(itemList);

    }

    public void setClickListener(OnclickListenerInterface onclickListener) {

        this.listener = onclickListener;
    }


    @Override
    public ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
        LayoutInflater inflater = LayoutInflater.from(context);     
        View view = inflater.inflate(R.layout.wordslist_two_rv, parent, false);          
        ViewHolder viewHolder = new ViewHolder(view);

        return viewHolder;
    }

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

        Astadhyayi word = wordList.get(position);
        holder.rsutras.setText(word.mSutras);



        // Animation******
        
        holder.rsutras.setTransitionName(word.getMSutras());


        if (word.mStatus != null && word.mStatus.equals(DictionaryDB.BOOKMARKED)) {

            holder.bookmark.setImageResource(R.drawable.cards_heart);
        } else {         

            holder.bookmark.setImageDrawable(null);
        }
    }

    @Override
    public Filter getFilter() {
        return Searched_Filter;
    }

    private Filter Searched_Filter = new Filter() {
        @Override
        protected FilterResults performFiltering(CharSequence constraint) {
            List<Astadhyayi> filteredList = new ArrayList<>();
            if (constraint == null || constraint.length() == 0) {
                filteredList.addAll(filwordList);
            } else {
                String filterPattern = constraint.toString().toLowerCase().trim();
                for (Astadhyayi item : filwordList) {
                    if (item.getMSutras().toLowerCase().contains(filterPattern)) {
                        filteredList.add(item);
                    }
                }
            }
            FilterResults results = new FilterResults();
            results.values = filteredList;
            return results;
        }
        @Override
        protected void publishResults(CharSequence constraint, FilterResults results) {
            wordList.clear();
            wordList.addAll((ArrayList<Astadhyayi>)results.values);
            notifyDataSetChanged();
        }
    };


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





    public class ViewHolder extends RecyclerView.ViewHolder implements View.OnClickListener {

        private TextView rsutras;
        private ImageView bookmark;

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

            itemView.setOnClickListener(this);

            rsutras =  itemView.findViewById(R.id.tvSansTerm);          
            bookmark = itemView.findViewById(R.id.bookmarkBtn);      

        }

        /*
         @Override
         public void onClick(View view) {

         if(listener!=null) listener.onItemClicked(getAbsoluteAdapterPosition(), rsutras);

         }
         */



        @Override
        public void onClick(View view) {



            int position = this.getAbsoluteAdapterPosition();   
            Astadhyayi word = wordList.get(position);

            //*************** Bundle  **************\
            Bundle bundle = new Bundle();

            bundle.putParcelable("allData", word);

            bundle.putString("transition_name", word.getMSutras());

            Fragment detailsFragment = new TermThreeDetailsFragment();
            detailsFragment.setSharedElementEnterTransition(new MaterialContainerTransform());
            detailsFragment.setArguments(bundle);

            FragmentTransaction fT =((AppCompatActivity)context).getSupportFragmentManager().beginTransaction();
            fT.setReorderingAllowed(true);
            fT.addSharedElement(rsutras, rsutras.getTransitionName()); // Shared element!
            fT.replace(R.id.fragment_container, detailsFragment);
            fT.addToBackStack(null);
            fT.commit();


        }


    }



}

RecyclerView 片段 Class（来源）

public class ShowtermsTwoFragment extends Fragment {

    private RecyclerView rv;
    private EditText tV;

    private Toolbar toolbar;
    private LinearLayoutManager layoutManager;
    private static DictionaryDB db;
    private RecyclerViewAdapter rvAdapter;

    private SearchView searchView = null;
    private SearchView.OnQueryTextListener queryTextListener;
    private List<Astadhyayi> wordsList = new ArrayList<>();

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        
        setExitTransition(new MaterialElevationScale(false));
        setReenterTransition(new MaterialElevationScale(true));
    }


    
    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
        View view = inflater.inflate(R.layout.fragment_terms_recyclerview, container, false);          
        return view;     
    }

    @Override
    public void onViewCreated(View view, Bundle savedInstanceState) {
        super.onViewCreated(view, savedInstanceState);

        toolbar = ((Toolbar) view.findViewById(R.id.toolbar_rv));
        rv = view.findViewById(R.id.rvTerms);
        tV = view.findViewById(R.id.tVinput);

        //*********** TOOLBAR
        AppCompatActivity activity = (AppCompatActivity) getActivity();
        activity.setSupportActionBar(toolbar);
        setHasOptionsMenu(true);   

        // new Get_DbData().execute();


        databaseCheck();
        recyclerCheck1();

        postponeEnterTransition();
        ((ViewGroup) view.getParent()).getViewTreeObserver()

            .addOnPreDrawListener(new ViewTreeObserver.OnPreDrawListener() {
                public boolean onPreDraw() { 
                    startPostponedEnterTransition();
                    return true;
                }
            });
        
        }

    private void databaseCheck() {

        String sanskritWord = getActivity().getIntent().getStringExtra("sanskritWord");

        //*********** @@@ DATABASE OPENING @@@ ***********\
        db = DictionaryDB.getInstance(this.getActivity());

        wordsList = db.getWords((sanskritWord));
    }



    private void recyclerCheck1() {

        layoutManager = new LinearLayoutManager(getContext());
        rv.setLayoutManager(layoutManager);
        rv.setHasFixedSize(true);


        DividerItemDecoration dividerItemDecoration = new DividerItemDecoration(rv.getContext(), layoutManager.getOrientation());
        rv.addItemDecoration(dividerItemDecoration);
        rvAdapter = new RecyclerViewAdapter(getContext(), wordsList, db);

        rv.setAdapter(rvAdapter);       
     /////**********   rvAdapter.setClickListener(this);      
        rvAdapter.notifyDataSetChanged();
    }
}

详细信息片段Class（目的地）

public class TermThreeDetailsFragment extends Fragment {


    private TextView sutraTV,vrittiTV,padaTv,adhyayTV,sutraIdTV ;
    private CoordinatorLayout coordinatorLayout;
    private FloatingActionButton fabBtn;
    private static DictionaryDB db;
    private Astadhyayi word;
    private BottomAppBar bottomAppBar;
    
    private TextToSpeech pronunciation;
    private AudioManager audio;
    private String ttsID , trans;

    
    
    
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        MaterialContainerTransform transform = new MaterialContainerTransform();
        transform.setScrimColor(Color.TRANSPARENT);
        setSharedElementEnterTransition(transform);
        setSharedElementReturnTransition(transform);
    }
    
    
    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
        View view = inflater.inflate(R.layout.show_three_details, container, false); 
        
        view.findViewById(R.id.tvSutra).setTransitionName(word.getMSutras());
        return view;
    }

    @Override
    public void onViewCreated(View view, Bundle savedInstanceState) {
        super.onViewCreated(view, savedInstanceState);
            
        sutraTV = view.findViewById(R.id.tvSutra);
        adhyayTV = view.findViewById(R.id.tVAdhyay);
        padaTv = view.findViewById(R.id.tVPada);
        sutraIdTV = view.findViewById(R.id.tVSutraId);
        vrittiTV = view.findViewById(R.id.tvVritti);

        fabBtn = view.findViewById(R.id.favFAB);
        coordinatorLayout = view.findViewById(R.id.parentCordlayout);
        bottomAppBar = view.findViewById(R.id.bottom_app_bar);   

   
        
        
        bundleCheckWithDb();  
        WordCheck();
        
        
    }

    
    
    
    
    private void bundleCheckWithDb() {

        
                            //***********  Geting Parcelable Data 
        word = new Astadhyayi(Parcel.obtain());
        Bundle bundle = this.getArguments();
        
        
        if (bundle != null) {
            word = bundle.getParcelable("allData"); 
            trans = bundle.getString("transition_name");
            
            adhyayTV.setText(word.getMAdhyay());
            padaTv.setText(word.getMPada());
            sutraIdTV.setText(word.getMSutra_id()); 
            sutraTV.setText(word.getMSutras());
            vrittiTV.setText(word.getMVritti()); 
        }

                           //*********** DATABASE OPENING
        db = DictionaryDB.getInstance(this.getActivity()); 
    }

    
    
    
    
    private void WordCheck() {

        if (word.mStatus != null && word.mStatus.equals(DictionaryDB.BOOKMARKED)) {
            fabBtn.setImageResource(R.drawable.cards_heart);
        } else {
            fabBtn.setImageResource(R.drawable.cards_heart_white);
        }

        fabBtn.setOnClickListener(new View.OnClickListener() {

                public void onClick(View v) {
                    bookMarkWord(word, fabBtn);
                }
            });
    }    
}

获取时出错

java.lang.NullPointerException: 尝试在空对象引用上调用虚拟方法 'java.lang.String com.sanskrit.mysearcher.models.Astadhyayi.getMSutras()' 在 com.sanskrit.mysearcher.fragments.TermThreeDetailsFragment.onCreateView(TermThreeDetailsFragment.java:69)

Answer 1

根据目前给出的信息，我认为你应该这样做：

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
    word = new Astadhyayi(Parcel.obtain());
    Bundle bundle = this.getArguments();
    if (bundle != null) {
        word = bundle.getParcelable("allData");
    }

    View view = inflater.inflate(R.layout.show_three_details, container, false); 
    view.findViewById(R.id.tvSutra).setTransitionName(word.getMSutras());
    return view;
}

同样，我不确定 getMSutras() 实际上 returns 以及在这里使用它是否正确。

Material 容器变换动画在 Java 中不起作用

Material Container Transform animation not working in Java

java

android

android-recyclerview

material-components-android

shared-element-transition