1.RecyclerView是什么

RecyclerView 在Android中用于创建列表。
官网的解释为： RecyclerView 可以让您轻松高效地显示大量数据。您提供数据并定义每个列表项的外观，而 RecyclerView 库会根据需要动态创建元素。
当RecyclerView的列表项滚出屏幕的时候，RecyclerView不会销毁该视图，相反而是将这些视图复用到新的列表项中。可以显著提高性能，改善响应能力并且减少功耗

2.RecyclerView怎么使用

确定列表或者网格的外观(流式布局、横向布局、纵向布局等)
设计列表中每一个项目的样式。通过样式来定义ViewHolder类
定义和ViewHolder相关联的Adapter

2.1定义布局

LinearLayoutManager： 列表布局
GridLayoutManager ： 网格布局
StaggeredGridLayoutManager： 流式布局

2.2定义ViewHolder和Adapter

示例代码：CustomAdapter.java


public class CustomAdapter extends RecyclerView.Adapter<CustomAdapter.ViewHolder> {private String[] localDataSet;/*** 自定义布局* (custom ViewHolder).*/public static class ViewHolder extends RecyclerView.ViewHolder {private final TextView textView;public ViewHolder(View view) {super(view);textView = (TextView) view.findViewById(R.id.textView);}public TextView getTextView() {return textView;}}/*** 构造函数，初始化数据集** @param dataSet String[] containing the data to populate views to be used* by RecyclerView.*/public CustomAdapter(String[] dataSet) {localDataSet = dataSet;}// 创建新的视图@Overridepublic ViewHolder onCreateViewHolder(ViewGroup viewGroup, int viewType) {// Create a new view, which defines the UI of the list itemView view = LayoutInflater.from(viewGroup.getContext()).inflate(R.layout.text_row_item, viewGroup, false);return new ViewHolder(view);}// 用来绑定数据@Overridepublic void onBindViewHolder(ViewHolder viewHolder, final int position) {viewHolder.getTextView().setText(localDataSet[position]);}// 返回数据集的大小@Overridepublic int getItemCount() {return localDataSet.length;}
}

列表单个项需要定义xml文件：text_row_item.xml

<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"android:layout_width="match_parent"android:layout_height="@dimen/list_item_height"android:layout_marginLeft="@dimen/margin_medium"android:layout_marginRight="@dimen/margin_medium"android:gravity="center_vertical"><TextViewandroid:id="@+id/textView"android:layout_width="wrap_content"android:layout_height="wrap_content"android:text="@string/element_text"/>
</FrameLayout>

2.3 Activity或者Fragment中使用

示例代码(fragment中)：RecyclerViewFragment.java


public class RecyclerViewFragment extends Fragment {protected RecyclerView mRecyclerView;protected CustomAdapter mAdapter;protected RecyclerView.LayoutManager mLayoutManager;protected String[] mDataset;private enum LayoutManagerType {GRID_LAYOUT_MANAGER,LINEAR_LAYOUT_MANAGER}@Overridepublic void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);initDataset();}@Overridepublic View onCreateView(LayoutInflater inflater, ViewGroup container,Bundle savedInstanceState) {View rootView = inflater.inflate(R.layout.recycler_view_frag, container, false);rootView.setTag(TAG);//定义RecyclerViewmRecyclerView = (RecyclerView) rootView.findViewById(R.id.recyclerView);//定义布局mLayoutManager = new LinearLayoutManager(getActivity());mRecyclerView.setLayoutManager(mLayoutManager);//初始化adaptermAdapter = new CustomAdapter(mDataset);//设置适配器mRecyclerView.setAdapter(mAdapter);return rootView;}//初始化数据private void initDataset() {mDataset = new String[60];for (int i = 0; i < 60; i++) {mDataset[i] = "This is element #" + i;}}
}

recycler_view_frag.xml


<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"android:layout_width="match_parent"android:layout_height="match_parent"android:orientation="vertical"><androidx.recyclerview.widget.RecyclerViewandroid:id="@+id/recyclerView"android:layout_width="match_parent"android:layout_height="match_parent"/>
</LinearLayout>