Android 使用RecyclerView实现横向滑动
前言
有个需求，实现类似GalleryView左右滑动功能，刚开始打算用HorizontalScrollView嵌套GridView实现，但发现这弊端太多了,Adapter功能基本废了…果断抛弃。
至于为什么不用GalleryView实现，呵呵，谁用谁知道！
后来搜了一下发现Google 在Android L中加入了RecyclerView,可通过引入support-v7包在低版本中使用，下面讲一下初次体验。
引入Support-v7.jar包
Gradle 导入
dependencies {
//省略其他引入....
//在build.gradle加上这一句就可以，很方便有木有
compile 'com.android.support:recyclerview-v7:+'
}至于其他环境，自己到sdk里找jar包吧…懒…
xml布局
<android.support.v7.widget.RecyclerView
xmlns:tools="http://schemas.android.com/tools"
xmlns:android="http://schemas.android.com/apk/res/android"
android:id="@+id/recycler_view"
android:layout_width="match_parent"
android:layout_height="wrap_content" />Activity代码
//必须设置LinearlayoutManager,不然无法用
LinearLayoutManager manager = new LinearLayoutManager(getActivity());
//设置水平方向滑动，在xml设置不生效
manager.setOrientation(LinearLayoutManager.HORIZONTAL);
recycleView.setLayoutManager(manager);
//设置适配器，跟ListView和gridView一样
recycleView.setAdapter(adapter);Adapter代码
跟ListView 和 GridView 的BaseAdapter有所不同，RecyclerView.Adapter直接复用的是Holder,而并非View.
public class PersonAdapter extends
RecyclerView.Adapter<PersonAdapter.Holder>{
private LayoutInflater mInflater;
private List<Person> mDatas;
public GalleryAdapter(List<Person> datats){
mDatas = datats;
}
//继承RecyclerView.ViewHolder
public static class Holder extends RecyclerView.ViewHolder{
TextView name;
TextView age;
public ViewHolder(View view){
super(view);
//初始化item
name = (TextView)view.findViewById(R.id.xxxx);
age = (TextView)view.findViewById(R.id.xxxx);
}
}
//获取总条目，相当于BaseAdapter里getCount
@Override
public int getItemCount(){
return mDatas.size();
}
/**
* 创建ViewHolder
*/
@Override
public ViewHolder onCreateViewHolder(ViewGroup viewGroup, int i){
View view = View.inflate(viewGroup.getContext(),R.layout.xx,
null);
Holder holder = new Holder(view);
return holder;
}
/**
* 设置值 ,相当于getView()
*/
@Override
public void onBindViewHolder(final ViewHolder holder, final int i){
holder.name.setText(mDatas.get(i).getName());
holder.age.setText(mDatas.get(i).getAge());
}
} 遇到的问题
NullPointException
java.lang.NullPointerException
at android.support.v7.widget.RecyclerView.onMeasure(RecyclerView.java:1694)
at android.view.View.measure(View.java:16497)
at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:5125)
...出现这异常，主要因为一开始我没给他配置LinearLayoutManager,解决方法：
//可以看上面的Activity代码
mLayoutManager = new LinearLayoutManager(this);
recycleView.setLayoutManager(mLayoutManager);Recycleview notifyDataSetChanged() IllegalStateException
java.lang.IllegalStateException: Cannot call this method while RecyclerView is computing a layout or scrolling
at android.support.v7.widget.RecyclerView.assertNotInLayoutOrScroll(RecyclerView.java:1462)
at android.support.v7.widget.RecyclerView$RecyclerViewDataObserver.onChanged(RecyclerView.java:2982)
at android.support.v7.widget.RecyclerView$AdapterDataObservable.notifyChanged(RecyclerView.java:7493)Stackoverflow上解决方法 猛击我，懒得贴代码
结语
大体上跟ListView，GridView使用差不多，再也不用担心横向滑动了
