代码清单10-9 在onResume（）方法中刷新列表项

package com.bignerdranch.android.criminallntent;

import android.content.Intent;
import android.os.Bundle;
import android.support.annotation.NonNull;
import android.support.v4.app.Fragment;
import android.support.v7.widget.LinearLayoutManager;
import android.support.v7.widget.RecyclerView;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ImageView;
import android.widget.TextView;
import android.widget.Toast;

import java.util.List;

public class CrimeListFragment extends Fragment{

    private RecyclerView mCrimeRecyclerView;
    private CrimeAdapter mAdapter;

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

        mCrimeRecyclerView=(RecyclerView) view.findViewById(R.id.crime_recycler_view);
        mCrimeRecyclerView.setLayoutManager(new LinearLayoutManager(getActivity()));

        updateUI();

        return view;
    }
    
    @Override
    public void onResume(){
        super.onResume();
        updateUI();
    }

    private  void updateUI(){
        CrimeLab crimeLab=CrimeLab.get(getActivity());
        List crimes=crimeLab.getCrimes();

        if(mAdapter==null){
            mAdapter=new CrimeAdapter(crimes);
            mCrimeRecyclerView.setAdapter(mAdapter);
        }else{
            mAdapter.notifyDataSetChanged();
        }
    }

    private class CrimeHolder extends RecyclerView.ViewHolder implements View.OnClickListener{

        private Crime mCrime;
        private TextView mTitleTextView;
        private  TextView mDateTextView;
        private ImageView mSolvedImageView;

        public CrimeHolder(LayoutInflater inflater,ViewGroup parent){
            super(inflater.inflate(R.layout.list_item_crime,parent,false));
            itemView.setOnClickListener(this);

            mTitleTextView=(TextView) itemView.findViewById(R.id.crime_title);
            mDateTextView=(TextView) itemView.findViewById(R.id.crime_date);
            mSolvedImageView=(ImageView)itemView.findViewById(R.id.crime_solved);
        }
        public void bind(Crime crime){
            mCrime=crime;
            mTitleTextView.setText(mCrime.getTitle());
            mDateTextView.setText(mCrime.getDate().toString());
            mSolvedImageView.setVisibility(crime.isSolved() ? View.VISIBLE : View.GONE);
        }

        @Override
        public void onClick(View view){
            Intent intent=CrimeActivity.newIntent(getActivity(),mCrime.getId());
            startActivity(intent);
        }
    }

    private 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());

            return new CrimeHolder(layoutInflater,parent);
        }

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

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