[2017-7-27]Android Learning Day5

总结篇！

吭哧吭哧了三天，最近不断研究《第一行代码：第二版》170多页的那个新闻实践项目，虽然也没有用到数据库和一些Web爬虫的知识，新闻数据都是随机生成的字符串。。。。。。

但还是很开心啊！！！！！！！！！！！！

成功的分离了大尺寸和小尺寸的设备的显示。

总而言之，练习了碎片，活动，最最基本的组件，还有RecycleView。

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其中最让我头疼的就是活动、活动布局、碎片、碎片布局的联系了有没有！

哦对，还有更头疼的，就是那个RecycleView的用法，简直爆炸。话不多说，快记录一下，不然一会又忘了。。。。。。

一、活动、活动布局、碎片、碎片布局的联系

就是这个图！嘿嘿，自己总结的，很明白，转载请注明！

1.活动通过布局文件名调用布局

public class MainActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
    }
}

2.3.布局文件上面注明碎片，且<碎片></碎片>引用碎片类。

<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/news_title_layout"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <fragment
        android:id="@+id/news_title_fragment"
        android:name="com.liwenchi.fragmentbestpractice.NewsTitleFragment"
        android:layout_width="match_parent"
        android:layout_height="match_parent" />

</FrameLayout>

4.碎片类引用碎片布局文件

public class NewsContentFragment extends Fragment {

    private View view;

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
        view = inflater.inflate(R.layout.news_content_frag, container, false);
        return view;
    }
}

恩，就是这样滴。

二、RecycleView的用法

 public class NewsTitleFragment extends Fragment {

     private boolean isTwoPane;

     public List<News> getNews() {

         List<News> newsList = new ArrayList<>();

         for(int i=1;i<=50;i++)
         {
             News news = new News();
             news.setTitle("This is news title "+i);
             news.setContent(getRandomLengthContent("This is news content "+ i));
             newsList.add(news);
         }
         return newsList;
     }

     private String getRandomLengthContent(String content) {
         Random random = new Random();
         int length = random.nextInt(20) + 1;
         StringBuilder builder = new StringBuilder();
         for(int i=0;i<length;i++)
         {
             builder.append(content+"\n");
         }
         return builder.toString();
     }

     //真正开始的代码
     @Override
     public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
         View view = inflater.inflate(R.layout.news_title_frag, container, false);
         //加载RecycleView
         RecyclerView newsTitleRecyclerView = (RecyclerView) view.findViewById(R.id.news_title_recycler_view);
         newsTitleRecyclerView.setLayoutManager(new LinearLayoutManager(getActivity()));
         newsTitleRecyclerView.setAdapter(new NewsAdapter(getNews()));

         return view;
     }

     @Override
     public void onActivityCreated(Bundle savedInstanceState) {
         super.onActivityCreated(savedInstanceState);
         if(getActivity().findViewById(R.id.news_content_layout) != null)
         {
             isTwoPane = true;
         }
         else
         {
             isTwoPane = false;
         }
     }

     class NewsAdapter extends RecyclerView.Adapter<NewsAdapter.ViewHolder> {

         private List<News> mNewList;

         //构造方法
         public NewsAdapter(List<News> newsList) {
             mNewList = newsList;
         }

         //自定义RecycleView的内容
         class ViewHolder extends RecyclerView.ViewHolder {
             //有一个Textview
             TextView newsTitleText;

             public  ViewHolder(View view) {
                 super(view);
                 newsTitleText = (TextView) view.findViewById(R.id.news_title);
             }
         }
         //实例化每一项
         @Override
         public ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
             View view = LayoutInflater.from(parent.getContext()).inflate(R.layout.news_item, parent, false);
             //把每一项view(TextView)实例化为一个ViewHolder
             final ViewHolder holder = new ViewHolder(view);
             //为每一个view绑定监听事件
             view.setOnClickListener(new View.OnClickListener() {
                 @Override
                 public void onClick(View v) {
                     News news = mNewList.get(holder.getAdapterPosition());
                     if(isTwoPane)
                     {
                         NewsContentFragment newsContentFragment = (NewsContentFragment) getFragmentManager().findFragmentById(R.id.news_content_fragment);
                         newsContentFragment.refresh(news.getTitle(), news.getContent());
                     }
                     else
                     {
                         NewsContentActivity.actionStart(getActivity(), news.getTitle(), news.getContent());
                     }
                 }
             });
             return holder;
         }
         //绑定每一个ViewHolder，因为这里有position参数。
         @Override
         public void onBindViewHolder(ViewHolder holder, int position) {
             News news = mNewList.get(position);
             holder.newsTitleText.setText(news.getTitle());
         }
         //RecycleView项的数量
         @Override
         public int getItemCount() {
             return mNewList.size();
         }
     }
 }