RecyclerView 搜索过滤器不起作用答案

【问题标题】：RecyclerView search filter is not workingRecyclerView 搜索过滤器不起作用
【发布时间】：2018-08-23 22:10:06
【问题描述】：

我想用搜索过滤一些 ArrayList 的数据，

在我的 Activity 的 onCreate 中：

        arrayList = getListItemData();
        filteredArrayList = new ArrayList<>();
        filteredArrayList.addAll(arrayList);

        adapter = new NameAdapter(filteredArrayList);
        itemList.setAdapter(adapter);

        searchBox.addTextChangedListener(new TextWatcher() {
            @Override
            public void beforeTextChanged(CharSequence s, int start, int count, int after) {

            }

            @Override
            public void onTextChanged(CharSequence s, int start, int before, int count) {

                adapter.getFilter().filter(s.toString());

            }

            @Override
            public void afterTextChanged(Editable s) {

            }
        });

我的可过滤适配器：

public class NameAdapter extends RecyclerView.Adapter<NameAdapter.ViewHolder> implements Filterable {
        private ArrayList<Name> arrayList;
        private CustomFilter filter;

        public NameAdapter(ArrayList<Branch> items) {
            arrayList = items;
            filter = new CustomFilter(NameAdapter.this);
        }

        @Override
        public ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
            View view = LayoutInflater.from(parent.getContext()).inflate(R.layout.item_name, parent, false);
            return new ViewHolder(view);
        }

        @Override
        public void onBindViewHolder(final ViewHolder holder, int position) {
            holder.data = arrayList.get(position);


        }

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

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

        public class ViewHolder extends RecyclerView.ViewHolder {
            public final View view;
            public final TextView branch;
            public Name data;

            public ViewHolder(View view) {
                super(view);
                this.view = view;
                branch = view.findViewById(R.id.textView_name);

            }

        }

        public class CustomFilter extends Filter {
            private NameAdapter adapter;

            private CustomFilter(NameAdapter adapter) {
                super();
                this.adapter = adapter;
            }

            @Override
            protected FilterResults performFiltering(CharSequence constraint) {
                filteredArrayList.clear();
                final FilterResults results = new FilterResults();
                if (constraint.length() == 0) {
                    filteredArrayList.addAll(arrayList);
                } else {
                    final String filterPattern = constraint.toString().toLowerCase().trim();
                    for (final Name name : arrayList) {
                        if (name.getName().toLowerCase().startsWith(filterPattern)) {
                            filteredBranchArrayList.add(name);
                        }
                    }
                }
                results.values = filteredArrayList;
                results.count = filteredArrayList.size();
                return results;
            }

            @Override
            protected void publishResults(CharSequence constraint, FilterResults results) {

                this.adapter.notifyDataSetChanged();
            }
        }
    }

过滤器由于某种原因不起作用，当我输入内容时它会清除回收站视图

【问题讨论】：

stackoverflow.com/questions/30398247/…
@SteveRuben 我想看看我自己的错误
在你的Adapter、filteredBranchArrayList 和branchArrayList 中指向同一个ArrayList，所以当你clear() filteredBranchArrayList 首先在performFiltering() 中，它会清除@987654331 @ 的branchArrayList 也是如此。我认为你只是在Activity 中得到branchArrayList，在Adapter 中得到branchArrayList 混淆。

标签： java android android-recyclerview

【解决方案1】：

首先在构造函数中复制branchArrayList。像这样：-

 private ArrayList<Branch> branchCopy = new ArrayList<>;
 public BranchAdapter(ArrayList<Branch> items) {
        branchArrayList = items;
        branchCopy.addAll(items);
        filter = new CustomFilter(BranchAdapter.this);
    }

你的performingFilter

  @Override
  protected FilterResults performFiltering(CharSequence constraint) {
        ArrayList<Branch> branchFilter = new ArrayList<>;
        final FilterResults results = new FilterResults();
            if (constraint.length() == 0) {
                branchFilter.addAll(branchArrayList);
            } else {
                final String filterPattern = constraint.toString().toLowerCase().trim();
                for (final Branch branch : branchCopy) {
                    if (branch.getBranchName().toLowerCase().startsWith(filterPattern)) {
                        branchFilter.add(branch);
                    }
                }
            }
            results.values = branchFilter ;
            results.count = branchFilter.size();
            return results;
        }

你的publishResults

  @Override
  protected void publishResults(CharSequence constraint, FilterResults results) {
      branchArrayList = (ArrayList<Branch>) results.values; // you have done nothing with the filter results 
      notifyDataSetChanged();
  }

在通知更改 mainList 之前 !!

 branchArrayList = (ArrayList<Branch>) results.values;

将此行添加到publishResults

您对过滤结果
做了NOTHING

【讨论】：

不，它现在可以工作了：你不能将 results.values 分配给 branchArrayList - 你必须有两个列表 - 一个用于所有项目，第二个用于过滤的项目
抱歉@pskink 很着急无法阅读他的完整问题，很明显你需要有两个列表！（初级逻辑）
您没有对副本列表进行任何操作。它有什么用？
branchCopy 是主列表（它将存储所有对象），branchArrayList 将具有 已过滤 列表（它可能包含也可能不包含所有对象） @VivekMishra

【解决方案2】：

尝试将您的适配器更改为

public class BranchAdapter extends RecyclerView.Adapter<BranchAdapter.ViewHolder> implements Filterable {
        private ArrayList<Branch> mArrayList;
        private ArrayList<Branch> mFilteredList;
        private CustomFilter filter;

        public BranchAdapter(ArrayList<Branch> items) {
            mArrayList = items;
            mFilteredList = items;
            filter = new CustomFilter(BranchAdapter.this);
        }

        @Override
        public ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
            View view = LayoutInflater.from(parent.getContext()).inflate(R.layout.item_branch, parent, false);
            return new ViewHolder(view);
        }

        @Override
        public void onBindViewHolder(final ViewHolder holder, int position) {
            holder.data = branchArrayList.get(position);
            holder.branch.setText(String.valueOf(mArrayList.get(position).getBranchCode() + " / " + mArrayList.get(position).getBranchName()));

        }

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

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

        public class ViewHolder extends RecyclerView.ViewHolder {
            public final View view;
            public final TextView branch;
            public Branch data;

            public ViewHolder(View view) {
                super(view);
                this.view = view;
                branch = view.findViewById(R.id.textView_branch);

            }

        }

        public class CustomFilter extends Filter {
            private BranchAdapter adapter;

            private CustomFilter(BranchAdapter adapter) {
                super();
                this.adapter = adapter;
            }

            @Override
            protected FilterResults performFiltering(CharSequence constraint) {

                String charString = charSequence.toString();

                if (charString.isEmpty()) {

                    mFilteredList = mArrayList;
                } else {

                    ArrayList<Branch> filteredList = new ArrayList<>();

                    for (Branch branch : mArrayList) {

                        if (branch.getBranchName().toLowerCase().contains(charString)) {

                            filteredList.add(branch);
                        }
                    }

                    mFilteredList = filteredList;
                }

                FilterResults filterResults = new FilterResults();
                filterResults.values = mFilteredList;
                return filterResults;
            }

            @Override
            protected void publishResults(CharSequence constraint, FilterResults results) {

                mFilteredList = (ArrayList<Branch>) filterResults.values;
                notifyDataSetChanged();
              //  this.adapter.notifyDataSetChanged();
            }
        }
    }

【讨论】：

【解决方案3】：

在执行 notifyDataSetChanged 之前，在 publishResults method 中更新您的 branchArrayList

【讨论】：

【解决方案4】：

使用以下代码更新您的PublishResults()

 @Override
        protected void publishResults(CharSequence charSequence, FilterResults filterResults) {
            filteredBranchArrayList = (ArrayList<Branch>) filterResults.values;
            notifyDataSetChanged();
        }

【讨论】：