Android仿支付宝应用分类

    <androidx.coordinatorlayout.widget.CoordinatorLayout            android:layout_width="match_parent"            android:layout_height="match_parent">

        <com.google.android.material.appbar.AppBarLayout                android:id="@+id/appbar"                android:layout_width="match_parent"                android:layout_height="wrap_content"                app:expanded="true"                app:elevation="0dp"                >
            <TextView                android:layout_width="match_parent"                android:layout_height="200dp"                android:text="顶部内容"                android:textSize="30sp"                android:gravity="center"                app:layout_scrollFlags="scroll"                />
                        <com.google.android.material.tabs.TabLayout                    android:id="@+id/tab_app_group"                    android:layout_width="match_parent"                    android:layout_height="50dp"                    android:background="#fff"                    app:tabTextColor="#333"                    app:tabSelectedTextColor="#f00"                    app:tabIndicatorColor="#f00"                    app:tabIndicatorFullWidth="false"                    app:tabInlineLabel="false"                    app:tabMode="scrollable"                    app:tabRippleColor="#fff"                    app:tabIndicatorHeight="1dp"                    />        com.google.android.material.appbar.AppBarLayout>

        <androidx.recyclerview.widget.RecyclerView                android:id="@+id/recycler_all"                android:layout_width="match_parent"                android:layout_height="match_parent"                android:background="#fff"                app:layout_behavior="@string/appbar_scrolling_view_behavior"                />
    androidx.coordinatorlayout.widget.CoordinatorLayout>
// app:elevation="0dp" 去除AppBarLayout底部黑线

        mTabLayout.addOnTabSelectedListener(new TabLayout.OnTabSelectedListener() {            @Override            public void onTabSelected(TabLayout.Tab tab) {                if (!isInit){                    mAppBar.setExpanded(false, true); //点击时置顶bar                }                if (isInit) isInit = false;
                //点击tab的时候，RecyclerView自动滑到该tab对应的item位置                int position = tab.getPosition();                if (!isScroll) {                    // 有动画且滚动到该分组                    mSmoothScroller.setTargetPosition(position);                    mLinearLayoutManager.startSmoothScroll(mSmoothScroller);                }            }
            @Override            public void onTabUnselected(TabLayout.Tab tab) {
            }
            @Override            public void onTabReselected(TabLayout.Tab tab) {
            }        });
        mRecyclerView.addOnScrollListener(new RecyclerView.OnScrollListener() {            @Override            public void onScrollStateChanged(RecyclerView recyclerView, int newState) {                super.onScrollStateChanged(recyclerView, newState);                if (newState == RecyclerView.SCROLL_STATE_IDLE) {                    isScroll = false;                } else {                    isScroll = true;                }            }
            @Override            public void onScrolled(RecyclerView recyclerView, int dx, int dy) {                super.onScrolled(recyclerView, dx, dy);                //滑动RecyclerView list的时候，根据最上面一个Item的position来切换tab//                mTabLayout.setScrollPosition(mLinearLayoutManager.findFirstVisibleItemPosition(), 0, true);                LinearLayoutManager layoutManager = (LinearLayoutManager) recyclerView.getLayoutManager();                TabLayout.Tab tabAt = mTabLayout.getTabAt(layoutManager.findFirstVisibleItemPosition());                if (tabAt != null && !tabAt.isSelected()) {                    tabAt.select();                }            }        });

    class AppGroupAdapter extends RecyclerView.Adapter{
        public static final int VIEW_TYPE_ITEM = 1;        public static final int VIEW_TYPE_FOOTER = 2;        protected List mData;
        /**         * item高度         */        private int itemHeight;
        private Context context;        public AppGroupAdapter(List data, Context context){            mData = data;            this.context = context;//            mRecycledViewPool = new RecyclerView.RecycledViewPool();        }
        @NonNull        @Override        public RecyclerView.ViewHolder onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {            if (viewType == VIEW_TYPE_ITEM) {                View view = LayoutInflater.from(context).inflate(R.layout.app_group, parent, false);                return new ItemVH(view);            } else {                //Footer是最后留白的位置，以便最后一个item能够出发tab的切换                View view = new View(context);                Log.e("footer", "parentHeight: " + mRecyclerViewHeight + "--" + "itemHeight: " + itemHeight);                view.setLayoutParams(                        new ViewGroup.LayoutParams(ViewGroup.LayoutParams.MATCH_PARENT,                                mRecyclerViewHeight - itemHeight));                return new FootVH(view);            }        }
        @Override        public void onBindViewHolder(@NonNull RecyclerView.ViewHolder holder, int position) {            if (holder.getItemViewType() == VIEW_TYPE_ITEM){                final ItemVH vh = (ItemVH) holder;                vh.tvGroup.setText(mData.get(position).getName());                vh.recyclerView.setRecycledViewPool(mRecycledViewPool);                vh.recyclerView.setHasFixedSize(false);//                vh.recyclerView.setNestedScrollingEnabled(false);
                GridLayoutManager gridLayoutManager = new GridLayoutManager(context, 4){
                    @Override                    public boolean canScrollVertically() {                        return false;                    }
                    @Override                    public void onLayoutCompleted(RecyclerView.State state) {                        super.onLayoutCompleted(state);                        mRecyclerViewHeight = mRecyclerView.getHeight();                        itemHeight = vh.itemView.getHeight();                    }                };                gridLayoutManager.setOrientation(RecyclerView.VERTICAL);
                vh.recyclerView.setLayoutManager(gridLayoutManager);
                AppsAdapter appsAdapter = new AppsAdapter(context);                appsAdapter.list.addAll(mData.get(position).getApps());                vh.recyclerView.setAdapter(appsAdapter);            }        }
        @Override        public int getItemCount() {            return mData.size() + 1;        }
        @Override        public int getItemViewType(int position) {            if (position == mData.size()) return  VIEW_TYPE_FOOTER;            return VIEW_TYPE_ITEM;        }
        class FootVH extends RecyclerView.ViewHolder{
            public FootVH(@NonNull View itemView) {                super(itemView);            }        }
        class ItemVH extends RecyclerView.ViewHolder{
            private TextView tvGroup;            private RecyclerView recyclerView;            public ItemVH(@NonNull View itemView) {                super(itemView);
                tvGroup = itemView.findViewById(R.id.tv_name);                recyclerView = itemView.findViewById(R.id.recycler);            }        }    }