Android提供了DiffUtil. callback()和DiffUtil. callback()。ItemCallback<T>它们帮助我们很好地过滤回收视图

DiffUtil是一个计算两者之差的实用程序类 列出并输出转换第一个更新操作的列表 列表到第二个。 https://developer.android.com/reference/androidx/recyclerview/widget/DiffUtil

DiffUtil.Callback()与RecyclerView一起使用。适配器

and

DiffUtil。ItemCallback与ListAdapter一起使用

使用RecyclerView过滤

创建你的RecyclerView，就像你通常会覆盖

onCreateViewHolder

onBindViewHolder

getItemCount

和扩展RecyclerView。ViewHolder类

就像您所做的那样(这是代码片段的Kotlin版本)

override fun onCreateViewHolder(viewGroup: ViewGroup, i: Int): ViewHolder? {
    val v: View = LayoutInflater.from(viewGroup.context)
        .inflate(R.layout.recycler_view_card_item, viewGroup, false)
    return ViewHolder(v)
}

fun onBindViewHolder(viewHolder: ViewHolder, i: Int) {
    val movie: Movie = mItems.get(i)
    viewHolder.tvMovie.setText(movie.getName())
    viewHolder.tvMovieRating.setText(movie.getRating())
}

override fun getItemCount(): Int {
    return mItems.size()
}

class ViewHolder(itemView: View) : RecyclerView.ViewHolder(itemView) {
    var tvMovie: TextView
    var tvMovieRating: TextView

    init {
        tvMovie = itemView.findViewById<View>(R.id.movieName) as TextView
        tvMovieRating = itemView.findViewById<View>(R.id.movieRating) as TextView
    }
}

现在创建另一个类来实现DiffUtil.Callback()

这个类将帮助将recyclerviews currentlist转换为过滤后的列表

class MoviesDiffUtilCallback(private val oldList: List<Movies>, private val newList: List<Movies>) : DiffUtil.Callback() {

override fun getOldListSize() = oldList.size

override fun getNewListSize() = newList.size

override fun areItemsTheSame(oldItemPosition: Int, newItemPosition: Int) = oldList[oldItemPosition].aUniqueId == newList[newItemPosition]. aUniqueId

//aUniqueId-> a field that is unique to each item in your listItems

override fun areContentsTheSame(oldItemPosition: Int, newItemPosition: Int) = oldList[oldItemPosition] == newList[newItemPosition]

}

在你的活动或片段类设置你的适配器和过滤器

private fun setupAdapter() {

//mItems is the list you will pass to the adapter
        adapter = CardAdapter(mItems)

        recyclerView.adapter = adapter

}

fun filter(searchText : String){

    val newFilter = mItems.filter {

        it.name.lowercase().contains(text.lowercase()) //filterlogic

    }

//Calculate the list of update operations that can covert one list into the other one 
    val diffResult = DiffUtil.calculateDiff(PostsDiffUtilCallback(mItems,newFilter))

    mItems.clear()


    mItems.addAll(newFilter)

//dispatch all updates to the RecyclerView
    diffResult.dispatchUpdatesTo(adapter)

}

使用ListAdapter进行筛选

我们将使用可过滤接口来帮助我们过滤(仍然在思考为什么我不应该直接使用过滤器函数来获取filteredLists和submitList(filteredLists))

创建你的ListAdapter类

class CardAdapter (
private val mItems : List<Movies>) : ListAdapter<Movies, CardAdapter.BillsPackageViewHolder>(MoviesDiffCallback()),
Filterable {

override fun onCreateViewHolder(viewGroup: ViewGroup, i: Int): ViewHolder? {
    val v: View = LayoutInflater.from(viewGroup.context)
        .inflate(R.layout.recycler_view_card_item, viewGroup, false)
    return ViewHolder(v)
}

fun onBindViewHolder(viewHolder: ViewHolder, i: Int) {
    val movie: Movie = mItems.get(i)
    viewHolder.tvMovie.setText(movie.getName())
    viewHolder.tvMovieRating.setText(movie.getRating())
}


override fun getFilter(): Filter {

    return object : Filter() {

        override fun performFiltering(constraint: CharSequence?): FilterResults {

            return FilterResults().apply {

                values = if (constraint.isNullOrEmpty())
                    mItems
                else
                    onFilter(mItems, constraint.toString())
            }
        }

        @Suppress("UNCHECKED_CAST")
        override fun publishResults(constraint: CharSequence?, results: FilterResults?) {

            submitList(results?.values as? List<Movies>)

        }
    }

}

fun onFilter(list: List<Movies>, constraint: String) : List<Movies>{

    val filteredList = list.filter {

        it.name.lowercase().contains(constraint.lowercase())

    }

    return filteredList

}

class ViewHolder(itemView: View) : RecyclerView.ViewHolder(itemView) {
    var tvMovie: TextView
    var tvMovieRating: TextView

    init {
        tvMovie = itemView.findViewById<View>(R.id.movieName) as TextView
        tvMovieRating = itemView.findViewById<View>(R.id.movieRating) as TextView
    }
}
}

现在创建另一个实现DiffUtil的类。ItemCallback

class MoviesDiffCallback : DiffUtil.ItemCallback<Movies>() {

override fun areItemsTheSame(oldItem: Movies, newItem: Movies): Boolean {
    return oldItem.someUniqueid == newItem.someUniqueid
}

override fun areContentsTheSame(oldItem: Movies, newItem: Movies): Boolean {
    return oldItem == newItem
}
}

在MainActivity或Fragment中设置适配器和过滤器

private fun setupAdapter() {

    adapter = CardAdapter(mItems)

    recyclerView.adapter = adapter

}

fun filter(searchString : String){

    adapter.filter.filter(searchString)

}

在适配器中添加接口。

public interface SelectedUser{

    void selectedUser(UserModel userModel);

}

在mainactivity中实现接口并重写方法。 @Override public void selectedUser(UserModel) {

    startActivity(new Intent(MainActivity.this, SelectedUserActivity.class).putExtra("data",userModel));



}

完整的教程和源代码: Recyclerview与searchview和onclicklistener

我不知道为什么每个人都用两个相同的列表来解决这个问题。这使用太多内存…

为什么不只是隐藏未找到的元素，并简单地将它们的索引存储在一个Set中，以便以后能够恢复它们呢?这样内存就少多了，特别是当你的对象很大的时候。

public class MyRecyclerViewAdapter extends RecyclerView.Adapter<MyRecyclerViewAdapter.SampleViewHolders>{
    private List<MyObject> myObjectsList; //holds the items of type MyObject
    private Set<Integer> foundObjects; //holds the indices of the found items

    public MyRecyclerViewAdapter(Context context, List<MyObject> myObjectsList)
    {
        this.myObjectsList = myObjectsList;
        this.foundObjects = new HashSet<>();
        //first, add all indices to the indices set
        for(int i = 0; i < this.myObjectsList.size(); i++)
        {
            this.foundObjects.add(i);
        }
    }

    @NonNull
    @Override
    public SampleViewHolders onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
        View layoutView = LayoutInflater.from(parent.getContext()).inflate(
                R.layout.my_layout_for_staggered_grid, null);
        MyRecyclerViewAdapter.SampleViewHolders rcv = new MyRecyclerViewAdapter.SampleViewHolders(layoutView);
        return rcv;
    }

    @Override
    public void onBindViewHolder(@NonNull SampleViewHolders holder, int position)
    {
        //look for object in O(1) in the indices set
        if(!foundObjects.contains(position))
        {
            //object not found => hide it.
            holder.hideLayout();
            return;
        }
        else
        {
            //object found => show it.
            holder.showLayout();
        }

        //holder.imgImageView.setImageResource(...)
        //holder.nameTextView.setText(...)
    }

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

    public void findObject(String text)
    {
        //look for "text" in the objects list
        for(int i = 0; i < myObjectsList.size(); i++)
        {
            //if it's empty text, we want all objects, so just add it to the set.
            if(text.length() == 0)
            {
                foundObjects.add(i);
            }
            else
            {
                //otherwise check if it meets your search criteria and add it or remove it accordingly
                if (myObjectsList.get(i).getName().toLowerCase().contains(text.toLowerCase()))
                {
                    foundObjects.add(i);
                }
                else
                {
                    foundObjects.remove(i);
                }
            }
        }
        notifyDataSetChanged();
    }

    public class SampleViewHolders extends RecyclerView.ViewHolder implements View.OnClickListener
    {
        public ImageView imgImageView;
        public TextView nameTextView;

        private final CardView layout;
        private final CardView.LayoutParams hiddenLayoutParams;
        private final CardView.LayoutParams shownLayoutParams;

        
        public SampleViewHolders(View itemView)
        {
            super(itemView);
            itemView.setOnClickListener(this);
            imgImageView = (ImageView) itemView.findViewById(R.id.some_image_view);
            nameTextView = (TextView) itemView.findViewById(R.id.display_name_textview);

            layout = itemView.findViewById(R.id.card_view); //card_view is the id of my androidx.cardview.widget.CardView in my xml layout
            //prepare hidden layout params with height = 0, and visible layout params for later - see hideLayout() and showLayout()
            hiddenLayoutParams = new CardView.LayoutParams(ViewGroup.LayoutParams.MATCH_PARENT,
                    ViewGroup.LayoutParams.WRAP_CONTENT);
            hiddenLayoutParams.height = 0;
            shownLayoutParams = new CardView.LayoutParams(ViewGroup.LayoutParams.MATCH_PARENT,
                    ViewGroup.LayoutParams.WRAP_CONTENT);
        }

        @Override
        public void onClick(View view)
        {
            //implement...
        }

        private void hideLayout() {
            //hide the layout
            layout.setLayoutParams(hiddenLayoutParams);
        }

        private void showLayout() {
            //show the layout
            layout.setLayoutParams(shownLayoutParams);
        }
    }
}

我只是有一个EditText作为我的搜索框:

cardsSearchTextView.addTextChangedListener(new TextWatcher() {
            @Override
            public void beforeTextChanged(CharSequence charSequence, int i, int i1, int i2) {

            }

            @Override
            public void onTextChanged(CharSequence charSequence, int i, int i1, int i2) {

            }

            @Override
            public void afterTextChanged(Editable editable) {
                myViewAdapter.findObject(editable.toString().toLowerCase());
            }
        });

结果:

通过使用LiveData的Android架构组件，这可以很容易地实现任何类型的适配器。你只需要做以下步骤:

1. 设置从房间数据库返回的数据为LiveData，如下例所示:

@Dao
public interface CustomDAO{

@Query("SELECT * FROM words_table WHERE column LIKE :searchquery")
    public LiveData<List<Word>> searchFor(String searchquery);
}

2. 创建一个ViewModel对象，通过连接DAO和UI的方法实时更新数据

public class CustomViewModel extends AndroidViewModel {

    private final AppDatabase mAppDatabase;

    public WordListViewModel(@NonNull Application application) {
        super(application);
        this.mAppDatabase = AppDatabase.getInstance(application.getApplicationContext());
    }

    public LiveData<List<Word>> searchQuery(String query) {
        return mAppDatabase.mWordDAO().searchFor(query);
    }

}

3.调用你的数据从ViewModel通过传入查询通过onQueryTextListener如下:

在onCreateOptionsMenu内部设置监听器，如下所示

searchView.setOnQueryTextListener(onQueryTextListener);

在SearchActivity类的某处设置查询侦听器，如下所示

private android.support.v7.widget.SearchView.OnQueryTextListener onQueryTextListener =
            new android.support.v7.widget.SearchView.OnQueryTextListener() {
                @Override
                public boolean onQueryTextSubmit(String query) {
                    getResults(query);
                    return true;
                }

                @Override
                public boolean onQueryTextChange(String newText) {
                    getResults(newText);
                    return true;
                }

                private void getResults(String newText) {
                    String queryText = "%" + newText + "%";
                    mCustomViewModel.searchQuery(queryText).observe(
                            SearchResultsActivity.this, new Observer<List<Word>>() {
                                @Override
                                public void onChanged(@Nullable List<Word> words) {
                                    if (words == null) return;
                                    searchAdapter.submitList(words);
                                }
                            });
                }
            };

注意:步骤(1.)和(2.)是标准的AAC ViewModel和DAO实现，这里唯一真正的“魔法”发生在OnQueryTextListener中，它将随着查询文本的变化动态更新列表的结果。

如果你需要更多关于此事的说明，请尽管问。 我希望这对你有所帮助:)。

我已经解决了同样的问题使用链接与一些修改。用卡片在RecyclerView上搜索过滤器。这可能吗?(希望这能有所帮助)。

这是我的适配器类

public class ContactListRecyclerAdapter extends RecyclerView.Adapter<ContactListRecyclerAdapter.ContactViewHolder> implements Filterable {

Context mContext;
ArrayList<Contact> customerList;
ArrayList<Contact> parentCustomerList;


public ContactListRecyclerAdapter(Context context,ArrayList<Contact> customerList)
{
    this.mContext=context;
    this.customerList=customerList;
    if(customerList!=null)
    parentCustomerList=new ArrayList<>(customerList);
}

   // other overrided methods

@Override
public Filter getFilter() {
    return new FilterCustomerSearch(this,parentCustomerList);
}
}

/ /过滤类

import android.widget.Filter;
import java.util.ArrayList;


public class FilterCustomerSearch extends Filter
{
private final ContactListRecyclerAdapter mAdapter;
ArrayList<Contact> contactList;
ArrayList<Contact> filteredList;

public FilterCustomerSearch(ContactListRecyclerAdapter mAdapter,ArrayList<Contact> contactList) {
    this.mAdapter = mAdapter;
    this.contactList=contactList;
    filteredList=new ArrayList<>();
}

@Override
protected FilterResults performFiltering(CharSequence constraint) {
    filteredList.clear();
    final FilterResults results = new FilterResults();

    if (constraint.length() == 0) {
        filteredList.addAll(contactList);
    } else {
        final String filterPattern = constraint.toString().toLowerCase().trim();

        for (final Contact contact : contactList) {
            if (contact.customerName.contains(constraint)) {
                filteredList.add(contact);
            }
            else if (contact.emailId.contains(constraint))
            {
                filteredList.add(contact);

            }
            else if(contact.phoneNumber.contains(constraint))
                filteredList.add(contact);
        }
    }
    results.values = filteredList;
    results.count = filteredList.size();
    return results;
}

@Override
protected void publishResults(CharSequence constraint, FilterResults results) {
    mAdapter.customerList.clear();
    mAdapter.customerList.addAll((ArrayList<Contact>) results.values);
    mAdapter.notifyDataSetChanged();
}

}

/ / Activity类

public class HomeCrossFadeActivity extends AppCompatActivity implements View.OnClickListener,OnFragmentInteractionListener,OnTaskCompletedListner
{
Fragment fragment;
 protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_homecrossfadeslidingpane2);CardView mCard;
   setContentView(R.layout.your_main_xml);}
   //other overrided methods
  @Override
   public boolean onCreateOptionsMenu(Menu menu) {
    // Inflate the menu; this adds items to the action bar if it is present.

    MenuInflater inflater = getMenuInflater();
    // Inflate menu to add items to action bar if it is present.
    inflater.inflate(R.menu.menu_customer_view_and_search, menu);
    // Associate searchable configuration with the SearchView
    SearchManager searchManager =
            (SearchManager) getSystemService(Context.SEARCH_SERVICE);
    SearchView searchView =
            (SearchView) menu.findItem(R.id.menu_search).getActionView();
    searchView.setQueryHint("Search Customer");
    searchView.setSearchableInfo(
            searchManager.getSearchableInfo(getComponentName()));

    searchView.setOnQueryTextListener(new SearchView.OnQueryTextListener() {
        @Override
        public boolean onQueryTextSubmit(String query) {
            return false;
        }

        @Override
        public boolean onQueryTextChange(String newText) {
            if(fragment instanceof CustomerDetailsViewWithModifyAndSearch)
                ((CustomerDetailsViewWithModifyAndSearch)fragment).adapter.getFilter().filter(newText);
            return false;
        }
    });



    return true;
}
}

在OnQueryTextChangeListener()方法中使用适配器。我已经把它铸造成碎片，因为我的适配器是碎片。如果它在您的活动类中，您可以直接使用适配器。

这是我对扩展@klimat答案不丢失过滤动画的看法。

public void filter(String query){
    int completeListIndex = 0;
    int filteredListIndex = 0;
    while (completeListIndex < completeList.size()){
        Movie item = completeList.get(completeListIndex);
        if(item.getName().toLowerCase().contains(query)){
            if(filteredListIndex < filteredList.size()) {
                Movie filter = filteredList.get(filteredListIndex);
                if (!item.getName().equals(filter.getName())) {
                    filteredList.add(filteredListIndex, item);
                    notifyItemInserted(filteredListIndex);
                }
            }else{
                filteredList.add(filteredListIndex, item);
                notifyItemInserted(filteredListIndex);
            }
            filteredListIndex++;
        }
        else if(filteredListIndex < filteredList.size()){
            Movie filter = filteredList.get(filteredListIndex);
            if (item.getName().equals(filter.getName())) {
                filteredList.remove(filteredListIndex);
                notifyItemRemoved(filteredListIndex);
            }
        }
        completeListIndex++;
    }
}

基本上，它所做的就是查看一个完整的列表，并逐个向过滤后的列表添加/删除项。