[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+"
");
        }
        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();
        }
    }
}