RecyclerView

添加依赖

compile 'com.android.support:recyclerview-v7:25.3.0'

然后就可以在布局文件里用RecyclerView控件了

• RecyclerView类是ViewGroup的子类，每一个列表项都是作为一个view子对象显示的
  RecyclerView负责回收和定位屏幕上子项的View
  定位是通过LayoutManager来实现的

mRecyclerView.setLayoutManager(new LinearLayoutManager(getActivity()));

• adapter是控制器对象，从模型层获取数据，然后提供给recyclerView显示

mRecyclerView.setAdapter(mAdapter);

• adapter还负责创建必要的ViewHolder,绑定ViewHolder与模型层数据
  适配器就在于把模型层数据（crimes）与视图层（ViewHolder）适配然后在适配进RecylerView中

• FindViewById(int)是耗时又耗内存的操作
  ViewHolder起到了保存FindViewById方法的成果的作用，大大减少的消耗

CrimeAdapter

public class CrimeAdapter extends RecyclerView.Adapter{

        private List mCrimes;

        public CrimeAdapter(List crimes){
            mCrimes=crimes;
        }

        @Override
//获取单项布局
        public CrimeHolder onCreateViewHolder(ViewGroup parent,int viewType)
        {
            LayoutInflater layoutInflater=LayoutInflater.from(getActivity());
            View view=layoutInflater.inflate(R.layout.list_item_crime,parent,false);
            return new CrimeHolder(view);
        }

        @Override
//将单项布局的控件用数据来配对填充
        public void onBindViewHolder(CrimeHolder holder,int position)
        {
            Crime crime=mCrimes.get(position);
            holder.bindHolder(crime);
        }

        @Override
//获取总项数
        public int getItemCount(){
            return mCrimes.size();
        }
    }
}

---

• ViewHolder的作用是存下并加载列表项的布局，所以在其构造函数中要传入布局文件，也可以在它构造的时候绑定监听事件
  CrimeHolder

public class CrimeHolder extends RecyclerView.ViewHolder
                 implements View.OnClickListener{
        private Crime mCrime;
        public TextView mTitleTextView;
        public TextView mDateTextView;
        public CheckBox mCheckBox;
        public CrimeHolder(View itemView){
            super(itemView);
//给列表项添加监听器也可以给列表项里的控件加
            itemView.setOnClickListener(this);
            mTitleTextView=(TextView)itemView.findViewById(R.id.title_text);
            mDateTextView=(TextView)itemView.findViewById(R.id.date_text);
            mCheckBox=(CheckBox)itemView.findViewById(R.id.check_box);
        }

        @Override
        public void onClick(View v){
            Toast.makeText(getActivity(),mCrime.getTitle()+"clicked!",Toast.LENGTH_SHORT).show();
        }
        //把绑定的代码写在viewHolder里然后在adapter里调用该方法更好
        public void bindHolder(Crime crime)
        {
            mCrime=crime;
            mTitleTextView.setText(mCrime.getTitle());
            mDateTextView.setText(mCrime.getDate().toString());
            mCheckBox.setChecked(mCrime.getSolved());
        }
    }

---

因为CrimeListActivity和CrimeActivity都是管理一个Fragment的Activity，而且用的是同样的布局，所以可以写一个抽象类来封装提交fragment事务的操作
因为管理的是不同的fragment所以需要让Activity重写创建fragment的部分

public abstract class SingleFragmentActivity extends FragmentActivity{
    //不能用private因为要在子类里去实现嘛
    protected abstract Fragment createNewFragment();
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_crime);

        FragmentManager fragmentManager=getSupportFragmentManager();
        Fragment fragment=fragmentManager.findFragmentById(R.id.fragment_container);

        if(fragment==null){
            fragment=createNewFragment();
            fragmentManager.beginTransaction().add(R.id.fragment_container,fragment).commit();
       }
    }
}

---

CrimeListFragment的完整代码

public class CrimeListFragment extends Fragment {
    private RecyclerView mRecyclerView;
    private CrimeAdapter mAdapter;


    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState)
    {
        View view=inflater.inflate(R.layout.crimelist_recycleview,container,false);
        mRecyclerView=(RecyclerView)view.findViewById(R.id.crimes_recycle_list);
        mRecyclerView.setLayoutManager(new LinearLayoutManager(getActivity()));
        updateUI();
        return view;
    }

    private void updateUI(){
        CrimeLab crimeLab=CrimeLab.get(getActivity());
        mAdapter=new CrimeAdapter(crimeLab.getCrimes());
        mRecyclerView.setAdapter(mAdapter);
    }

    public class CrimeHolder extends RecyclerView.ViewHolder
                 implements View.OnClickListener{
        private Crime mCrime;
        public TextView mTitleTextView;
        public TextView mDateTextView;
        public CheckBox mCheckBox;
        public CrimeHolder(View itemView){
            super(itemView);
            itemView.setOnClickListener(this);
            mTitleTextView=(TextView)itemView.findViewById(R.id.title_text);
            mDateTextView=(TextView)itemView.findViewById(R.id.date_text);
            mCheckBox=(CheckBox)itemView.findViewById(R.id.check_box);
        }

        @Override
        public void onClick(View v){
            Toast.makeText(getActivity(),mCrime.getTitle()+"clicked!",Toast.LENGTH_SHORT).show();
        }
        //把绑定的代码写在viewHolder里然后在adapter里调用该方法更好
        public void bindHolder(Crime crime)
        {
            mCrime=crime;
            mTitleTextView.setText(mCrime.getTitle());
            mDateTextView.setText(mCrime.getDate().toString());
            mCheckBox.setChecked(mCrime.getSolved());
        }
    }

    public class CrimeAdapter extends RecyclerView.Adapter{

        private List mCrimes;

        public CrimeAdapter(List crimes){
            mCrimes=crimes;
        }

        @Override
        public CrimeHolder onCreateViewHolder(ViewGroup parent,int viewType)
        {
            LayoutInflater layoutInflater=LayoutInflater.from(getActivity());
            View view=layoutInflater.inflate(R.layout.list_item_crime,parent,false);
            return new CrimeHolder(view);
        }

        @Override
        public void onBindViewHolder(CrimeHolder holder,int position)
        {
            Crime crime=mCrimes.get(position);
            holder.bindHolder(crime);
        }

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