Android如何实现多级筛选，代码演示

Android实现多级筛选可以使用RecyclerView和PopupWindow来实现。以下是一个简单的演示代码：

1. 首先创建一个RecyclerView用于展示筛选条件：

<androidx.recyclerview.widget.RecyclerView
    android:id="@+id/filter_list"
    android:layout_width="match_parent"
    android:layout_height="match_parent" />

2. 创建一个PopupWindow用于展示筛选条件的选项：

public class FilterPopupWindow extends PopupWindow {

    private Context mContext;
    private RecyclerView mRecyclerView;
    private FilterAdapter mAdapter;
    private List<String> mData;

    public FilterPopupWindow(Context context, List<String> data) {
        super(context);
        mContext = context;
        mData = data;
        initView();
    }

    private void initView() {
        View view = LayoutInflater.from(mContext).inflate(R.layout.popup_filter, null);
        mRecyclerView = view.findViewById(R.id.filter_option_list);
        mRecyclerView.setLayoutManager(new LinearLayoutManager(mContext));
        mAdapter = new FilterAdapter(mData);
        mRecyclerView.setAdapter(mAdapter);
        setContentView(view);
        setWidth(ViewGroup.LayoutParams.MATCH_PARENT);
        setHeight(ViewGroup.LayoutParams.WRAP_CONTENT);
        setFocusable(true);
        setOutsideTouchable(true);
        setBackgroundDrawable(new ColorDrawable(Color.TRANSPARENT));
    }

    public void setOnItemClickListener(FilterAdapter.OnItemClickListener listener) {
        mAdapter.setOnItemClickListener(listener);
    }
}

3. 创建一个筛选条件的Adapter：

public class FilterAdapter extends RecyclerView.Adapter<FilterAdapter.ViewHolder> {

    private List<String> mData;
    private int mSelectedPosition = -1;
    private OnItemClickListener mItemClickListener;

    public FilterAdapter(List<String> data) {
        mData = data;
    }

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

    @Override
    public void onBindViewHolder(@NonNull ViewHolder holder, int position) {
        holder.mOption.setText(mData.get(position));
        holder.mOption.setSelected(position == mSelectedPosition);
        holder.itemView.setOnClickListener(v -> {
            if (mItemClickListener != null) {
                mItemClickListener.onItemClick(position);
            }
        });
    }

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

    public void setSelectedPosition(int position) {
        mSelectedPosition = position;
        notifyDataSetChanged();
    }

    public interface OnItemClickListener {
        void onItemClick(int position);
    }

    public void setOnItemClickListener(OnItemClickListener listener) {
        mItemClickListener = listener;
    }

    static class ViewHolder extends RecyclerView.ViewHolder {

        private TextView mOption;

        public ViewHolder(@NonNull View itemView) {
            super(itemView);
            mOption = itemView.findViewById(R.id.filter_option);
        }
    }
}

4. 在Activity中使用RecyclerView和PopupWindow实现多级筛选：

public class MainActivity extends AppCompatActivity {

    private RecyclerView mFilterList;
    private FilterAdapter mFilterAdapter;
    private List<String> mFilterData;
    private FilterPopupWindow mPopupWindow;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        mFilterList = findViewById(R.id.filter_list);
        initFilterData();
        mFilterAdapter = new FilterAdapter(mFilterData);
        mFilterList.setLayoutManager(new LinearLayoutManager(this, LinearLayoutManager.HORIZONTAL, false));
        mFilterList.setAdapter(mFilterAdapter);
        mFilterAdapter.setOnItemClickListener(position -> {
            mFilterAdapter.setSelectedPosition(position);
            showPopupWindow(position);
        });
    }

    private void initFilterData() {
        mFilterData = new ArrayList<>();
        mFilterData.add("品牌");
        mFilterData.add("价格");
        mFilterData.add("颜色");
    }

    private void showPopupWindow(int position) {
        if (mPopupWindow == null) {
            mPopupWindow = new FilterPopupWindow(this, Arrays.asList("华为", "小米", "苹果"));
            mPopupWindow.setOnDismissListener(() -> mFilterAdapter.setSelectedPosition(-1));
            mPopupWindow.setOnItemClickListener(position1 -> {
                mPopupWindow.dismiss();
                // TODO: 处理筛选结果
            });
        } else {
            mPopupWindow.dismiss();
        }
        int[] location = new int[2];
        mFilterList.getChildAt(position).getLocationInWindow(location);
        mPopupWindow.showAtLocation(mFilterList, Gravity.NO_GRAVITY, location[0], location[1] + mFilterList.getChildAt(position).getHeight());
    }
}

以上是一个简单的多级筛选的演示代码，可以根据具体需求进行修改和优化。