RecyclerView增 删

、、、、、、、、、、、对应相关主布局
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"    xmlns:tools="http://schemas.android.com/tools"    android:layout_width="match_parent"    android:layout_height="match_parent" >    <LinearLayout        android:id="@+id/one"        android:layout_width="wrap_content"        android:layout_height="wrap_content">        <Button            android:id="@+id/b1"            android:layout_width="wrap_content"            android:layout_height="wrap_content"            android:text="添加"            />        <Button            android:id="@+id/b2"            android:layout_toRightOf="@+id/b1"            android:layout_width="wrap_content"            android:layout_height="wrap_content"            android:text="删除"            />        <Button            android:id="@+id/b3"            android:layout_toRightOf="@+id/b1"            android:layout_width="wrap_content"            android:layout_height="wrap_content"            android:text="list"            />        <Button            android:id="@+id/b4"            android:layout_toRightOf="@+id/b1"            android:layout_width="wrap_content"            android:layout_height="wrap_content"            android:text="group"            />        <Button            android:id="@+id/b5"            android:layout_toRightOf="@+id/b1"            android:layout_width="wrap_content"            android:layout_height="wrap_content"            android:text="PB"            />    </LinearLayout>    <android.support.v7.widget.RecyclerView        android:layout_below="@+id/one"        android:id="@+id/id_recyclerview"        android:divider="#ffff0000"        android:dividerHeight="10dp"        android:layout_width="match_parent"        android:layout_height="match_parent" /></RelativeLayout>
public class MainActivity extends AppCompatActivity  implements View.OnClickListener{    String uri = "http://api.tianapi.com/social/?key=71e58b5b2f930eaf1f937407acde08fe&num=20";    TextView id_num ,tv;    ImageView img;    private RecyclerView mRecyclerView;    private HomeAdapter mAdapter;    List<News.NewslistBean> mDatas;    ImageLoader imagerloder;    Button b1,b2,b3,b4,b5;    @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_main);        id_num=(TextView)findViewById(R.id.id_num);        img= (ImageView)findViewById(R.id.img);        tv=(TextView)findViewById(R.id.tv);        b1=(Button)findViewById(R.id.b1) ;        b2=(Button)findViewById(R.id.b2) ;        b3=(Button)findViewById(R.id.b3) ;        b4=(Button)findViewById(R.id.b4) ;        b5=(Button)findViewById(R.id.b5) ;        mRecyclerView = (RecyclerView) findViewById(R.id.id_recyclerview);        //listview的效果        mRecyclerView.setLayoutManager(new LinearLayoutManager(this));        //下划线        mRecyclerView.addItemDecoration(new DividerItemDecoration(this,                DividerItemDecoration.VERTICAL_LIST));        //groupview的效果       /* mRecyclerView.setLayoutManager(new GridLayoutManager(this,3));*/        //瀑布效果       /* mRecyclerView.setLayoutManager(new StaggeredGridLayoutManager(5, StaggeredGridLayoutManager.VERTICAL));*/            //网络判断        boolean netWorkAvailable = NetWorkUtils.isNetWorkAvailable(this);        if(!netWorkAvailable){            Toast.makeText(MainActivity.this, "联网：" + netWorkAvailable, Toast.LENGTH_SHORT).show();        }        getData();       b1.setOnClickListener(this);        b2.setOnClickListener(this);        b3.setOnClickListener(this);        b4.setOnClickListener(this);        b5.setOnClickListener(this);    }    public void getData() {        OkHttp3Utils.getInstance().doGet(uri, new GsonObjectCallback<News>() {            @Override            public void onUi(News news) {                mDatas = news.getNewslist();                mRecyclerView.setAdapter(mAdapter = new HomeAdapter());            }            @Override            public void onFailed(Call call, IOException e) {            }        });    }    @Override    public void onClick(View v) {        switch (v.getId())        {            case R.id.b1:                mAdapter.addData(1);             break;            case R.id.b2:                mAdapter.removeData(1);                break;            case R.id.b3:                mRecyclerView.setLayoutManager(new LinearLayoutManager(this));                break;            case R.id.b4:                mRecyclerView.setLayoutManager(new GridLayoutManager(this,3));                break;              case   R.id.b5:                  mRecyclerView.setLayoutManager(new StaggeredGridLayoutManager(5, StaggeredGridLayoutManager.VERTICAL));                break;        }    }    class HomeAdapter extends RecyclerView.Adapter<HomeAdapter.MyViewHolder>    {        @Override        public MyViewHolder onCreateViewHolder(ViewGroup parent, int viewType)        {            MyViewHolder holder = new MyViewHolder(LayoutInflater.from(                    MainActivity.this).inflate(R.layout.item, parent,                    false));            return holder;        }        @Override        public void onBindViewHolder(MyViewHolder holder, int position)        {            holder.id_num.setText(mDatas.get(position).getDescription());            holder.tv.setText(mDatas.get(position).getTitle());             imagerloder =ImageLoader.getInstance();            imagerloder.displayImage(mDatas.get(position).getPicUrl(),holder.img);            // 获得该控件的所有属性            ViewGroup.LayoutParams layoutParams = holder.tv.getLayoutParams();            Random random = new Random();            layoutParams.height = random.nextInt(200)+50;            holder.tv.setLayoutParams(layoutParams);        }        @Override        public int getItemCount()        {            return mDatas.size();        }        class MyViewHolder extends RecyclerView.ViewHolder        {            TextView id_num;            ImageView img;            TextView tv;            public MyViewHolder(View view)            {                super(view);                tv = (TextView)view.findViewById(R.id.tv);                id_num = (TextView) view.findViewById(R.id.id_num);                img = (ImageView)view.findViewById(R.id.img);            }        }        /*添加和删除的方法*/        public void addData(int position) {            mDatas.add(position, new News.NewslistBean("sss","sss",null));            notifyItemInserted(position);        }        public void removeData(int position) {            mDatas.remove(position);            notifyItemRemoved(position);        }    }