已适配 Androidx，需要切到 androidx 分支即可

一种新的解决思路，对比我之前写的PinnedSectionItemDecoration有如下好处：

• 粘性头部是放置在 RecyclerView 外面的 View，对比之前绘制出来的粘性头部，能显示出点击的效果，并且处理点击事件更加简单

• 不需要频繁的创建粘性头部的 View 用于绘制，只需要刷新外置的粘性头部的数据即可

效果图

代码实现

StickyHeadContainer 用来承载粘性头部布局，并且需要和 RecyclerView 的顶部对齐

<RelativeLayout
    android:id="@+id/content_main"
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    app:layout_behavior="@string/appbar_scrolling_view_behavior"
    tools:context="com.oubowu.stickydemo.MainActivity"
    tools:showIn="@layout/activity_main">

    <android.support.v7.widget.RecyclerView
        android:id="@+id/recycler_view"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:layout_alignParentTop="true"
        android:layout_margin="10dp"
        tools:background="@color/colorAccent"
        android:layout_alignParentLeft="true"
        android:layout_alignParentStart="true">

    </android.support.v7.widget.RecyclerView>

    <com.oubowu.stickyitemdecoration.StickyHeadContainer
        android:id="@+id/shc"
        android:layout_width="match_parent"
        android:layout_margin="10dp"
        android:layout_height="wrap_content">

        <include
            layout="@layout/item_stock_sticky_head"/>

    </com.oubowu.stickyitemdecoration.StickyHeadContainer>

</RelativeLayout>

RecyclerView 只需要添加一个 StickyItemDecoration 即可实现粘性头部，需要传入 StickyHeadContainer 用于头部的处理，以及粘性头部的类型；然后头部的点击处理就像平常一样处理

        final StickyHeadContainer container = (StickyHeadContainer) findViewById(R.id.shc);
        final TextView tvStockName = (TextView) container.findViewById(R.id.tv_stock_name);
        final CheckBox checkBox = (CheckBox) container.findViewById(R.id.checkbox);
        final ImageView more = (ImageView) container.findViewById(R.id.iv_more);
        checkBox.setOnCheckedChangeListener(new CompoundButton.OnCheckedChangeListener() {
            @Override
            public void onCheckedChanged(CompoundButton buttonView, boolean isChecked) {
                mAdapter.getData().get(mStickyPosition).getData().check = isChecked;
                mAdapter.notifyItemChanged(mStickyPosition);
            }
        });
        container.setDataCallback(new StickyHeadContainer.DataCallback() {
            @Override
            public void onDataChange(int pos) {
                mStickyPosition = pos;
                StockEntity.StockInfo item = mAdapter.getData().get(pos).getData();
                tvStockName.setText(item.stickyHeadName);
                checkBox.setChecked(item.check);
            }
        });
        more.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                Toast.makeText(MainActivity.this, "点击了粘性头部的更多", Toast.LENGTH_SHORT).show();
            }
        });
        container.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                Toast.makeText(MainActivity.this, "点击了粘性头部：" + tvStockName.getText(), Toast.LENGTH_SHORT).show();
            }
        });

        mRecyclerView = (RecyclerView) findViewById(R.id.recycler_view);
        mRecyclerView.setLayoutManager(new LinearLayoutManager(MainActivity.this, LinearLayoutManager.VERTICAL, false));
        mRecyclerView.addItemDecoration(new StickyItemDecoration(container, RecyclerViewAdapter.TYPE_STICKY_HEAD));
        mRecyclerView.addItemDecoration(new SpaceItemDecoration(mRecyclerView.getContext()));

Adapter 需要重写这两个方法，用于处理 GridLayoutManager 和 StaggeredGridLayoutManager 模式下的头部使之占满一行

    @Override
    public void onAttachedToRecyclerView(RecyclerView recyclerView) {
        super.onAttachedToRecyclerView(recyclerView);
        FullSpanUtil.onAttachedToRecyclerView(recyclerView, this, TYPE_STICKY_HEAD);
    }

    @Override
    public void onViewAttachedToWindow(RecyclerViewHolder holder) {
        super.onViewAttachedToWindow(holder);
        FullSpanUtil.onViewAttachedToWindow(holder, this, TYPE_STICKY_HEAD);
    }

PS:若是使用了下拉刷新的控件配合 RecyclerView 使用的话(显示刷新头部并且 RecyclerView 跟随头部的显示往下移动那种类型)，因为 StickyHeadContainer 是独立于 RecyclerView 存在的，不能跟随 RecyclerView 移动，需要根据刷新头部的显示情况设置 StickyHeadContainer 的可见性

License

Copyright 2016 oubowu

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

   http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.