碎片的最佳实践 《第一行代码Android》

从14：00到20：00一直在做这个实践，毕竟自己也是刚刚开始学习Android 开发，实践过程中也是一直遇到各种各样的问题。下图是最终该一个结果，因为我用的是真机，因此只用手机测试了一下。

最终的项目结构就是这样。总的说这个的思路并不是很难，但是由于它是一部分一部分教的，因此需要按照步骤一步步进行，不行写错地方，或者少写了一些函数，或者是直接粘贴复制。说说自己遇到的问题吧：
1.一开始写的项目有很多错误，于是我重新创建了一个项目，原本图省事，没想到粘贴复制过来的代码系统不识别，很多关键词直接报错，只好重新写那些关键词并导入对应的包

2.一定要按照书本上的原原本本的进行操作！！！否则你会非常痛苦，除非你思路很清晰。我和书本上xml文件的命名方法有几个不同，导致最后在引用对应的xml中的id的时候，需要思考很长时间....这段代码到底要实现什么功能...然后去找xml文件中的进行对应...累

3.一个很容易遇到的问题是Fragment的问题！！！！就像书上说的那样，可能会有两个不同包下的Fragment供你选择，一个是系统内置的android.app.Fragment,另一个是support-v4库中的android.support.v4.app.Fragment.书本强烈建议使用后者，因为它可以让碎片在所有Android系统版本中保持功能一致性。也就是说对于这个问题的处理方法可以是以下所示的（仅供参考）

将import android.app.Fragment; 改为import android.support.v4.app.Fragment;以及将getSupportFragmentManager()改为getFragmentManager()如下图所示

如果你在建class的时候没有extends Fragment可会出现这个问题...直接加上就好

4.因为这本书是按照步骤一步步教我们实践的，因此很可能做到后面我们会把代码写错地方，这时候它会提示“...method cannot applied to...”诸如此类，此时一定要有耐心，重新看着书本整理一下代码出现的顺序.

5.超级不喜欢Android studio 中的提示，我总以为它的提示是正确的,but...最后很多书写错误都是因为它“善意的”提示。

不管怎么说，祝大家好运，一定要相信：是你的代码写错了而不是书本有问题！！！！

//MainActivity

package com.example.hui.fragmentbestpractice;

import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;

public class MainActivity extends AppCompatActivity {

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

//News

package com.example.hui.fragmentbestpractice;

/**
 * Created by hui on 2018/1/24.
 */

public class News {
    private String title;
    private String content;

    public String getTitle(){
        return title;
    }

    public void setTitle(String title){
        this.title = title;
    }

    public String getContent(){
        return content;
    }

    public void setContent(String content){
        this.content = content;

    }}

//NewsContentActivity

package com.example.hui.fragmentbestpractice;

import android.content.Context;
import android.content.Intent;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;

public class NewsContentActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_news_content);
        String newsTitle = getIntent().getStringExtra("news_title");
        String newsContent = getIntent().getStringExtra("activity_news_content");
        NewsContentFragment newsContentFragment= (NewsContentFragment)getSupportFragmentManager().findFragmentById(R.id.news_content_fragment);
        newsContentFragment.refresh(newsTitle,newsContent);
    }

        public static void actionStart(Context context, String newsTitle, String newsContent){
            Intent intent = new Intent(context,NewsContentActivity.class);
            intent.putExtra("news_title",newsTitle);
            intent.putExtra("news_content",newsContent);
            context.startActivity(intent);

        }


}

//NewsContentFragment

package com.example.hui.fragmentbestpractice;

import android.support.v4.app.Fragment;
//import android.app.Fragment;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.TextView;

/**
 * Created by hui on 2018/1/24.
 */

public class NewsContentFragment extends Fragment {
    private View view;

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

    public void refresh(String newsTitle,String newsContent){
        View visibilityLayout = view.findViewById(R.id.visibility_layout);
        visibilityLayout.setVisibility(View.VISIBLE);
        TextView newsTitleText = (TextView)view.findViewById(R.id.news_title);
        TextView newsContentText = (TextView)view.findViewById(R.id.news_content);
        newsTitleText.setText(newsTitle);
        newsContentText.setText(newsContent);
    }
}

//NewsTitleFragment

package com.example.hui.fragmentbestpractice;

import android.support.v4.app.Fragment;
import android.content.Context;
import android.os.Bundle;
import android.support.v7.widget.LinearLayoutManager;
import android.support.v7.widget.RecyclerView;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.app.Activity;
import android.view.View;
import android.view.ViewGroup;
import android.widget.TextView;

import java.util.ArrayList;
import java.util.List;
import java.util.Random;

import static android.content.ContentValues.TAG;

/**
 * Created by hui on 2018/1/24.
 */

public class NewsTitleFragment extends Fragment{
    private boolean isTwoPane;


    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState){
        View view = inflater.inflate(R.layout.news_title_frag,container,false);
        RecyclerView newsTitleRecyclerView = (RecyclerView)view.findViewById(R.id.news_title_recycle_view);
        LinearLayoutManager LayoutManger = new LinearLayoutManager(getActivity());
        newsTitleRecyclerView.setLayoutManager(LayoutManger);
        NewsAdapter adapter = new NewsAdapter(getNews());
        newsTitleRecyclerView.setAdapter(adapter);
        return view;


    }

    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> mNewsList;

         class ViewHolder extends RecyclerView.ViewHolder {
             TextView newsTitleText;

             public ViewHolder(View view) {
                 super(view);
                 newsTitleText = (TextView) view.findViewById(R.id.news_title);
             }
         }

         public NewsAdapter(List<News> newsList) {
             mNewsList = newsList;
         }

         public NewsAdapter.ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
             View view = LayoutInflater.from(parent.getContext()).inflate(R.layout.news_item, parent, false);
             final ViewHolder holder = new ViewHolder(view);
             view.setOnClickListener(new View.OnClickListener() {
                 @Override
                 public void onClick(View v) {
                     News news = mNewsList.get(holder.getAdapterPosition());
                     if (isTwoPane) {
                         NewsContentFragment newsContentFragment = (NewsContentFragment) getFragmentManager().findFragmentById(R.id.news_content_fragment);
                         //NewsContentFragment newsContentFragment =(NewsContentFragment)getSupportFragmentManager().findFragmentById(R.id.news_content_fragment);
                         newsContentFragment.refresh(news.getTitle(), news.getContent());
                     } else {
                         NewsContentActivity.actionStart(getActivity(), news.getTitle(), news.getContent());
                     }
                 }
             });
             return holder;
         }

         @Override
         public void onBindViewHolder(NewsAdapter.ViewHolder holder, int position) {
             News news = mNewsList.get(position);
             holder.newsTitleText.setText(news.getTitle());
         }

         @Override
         public int getItemCount() {
             return mNewsList.size();
         }
     }

         private 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();
         }


}