Volley请求数据展示到pulltorefreshlistview并添加数据库

public class MainActivity extends AppCompatActivity {

    PullToRefreshListView pullToRefreshListView;
    String url="http://www.qubaobei.com/ios/cf/dish_list.php?stage_id=1&limit=20&page=";
    List list;
    MyAdapter myAdapter;
    private int page=1;
    Button b1,b2;
    DaoSession daoSession;
    DataBean dataBean;

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

        pullToRefreshListView=findViewById(R.id.My_Pt);
        pullToRefreshListView.setMode((PullToRefreshBase.Mode.BOTH));

        b1=findViewById(R.id.b1);
        b2=findViewById(R.id.b2);
        daoSession=MyApp.getdaosession();
        b1.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                for (int i=0;i<list.size();i++){
                    dataBean=new DataBean(list.get(i).getTitle(),
                            list.get(i).getPic(),
                            list.get(i).getFood_str(),
                            list.get(i).getCollect_num());
                    daoSession.insert(dataBean);
                }
                Toast.makeText(MainActivity.this,"添加成功",Toast.LENGTH_SHORT).show();
            }
        });


        b2.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                QueryBuilder dataBeanQueryBuilder=daoSession.queryBuilder(DataBean.class);
                List list1 = dataBeanQueryBuilder.list();
                Toast.makeText(MainActivity.this, list1.get(1).getTitle(), Toast.LENGTH_SHORT).show();
            }
        });

        myAdapter=new MyAdapter(MainActivity.this);
        getdata(1);
        pullToRefreshListView.setOnRefreshListener(new PullToRefreshBase.OnRefreshListener2() {
            @Override
            public void onPullDownToRefresh(PullToRefreshBase pullToRefreshBase) {
                list.clear();
                getdata(1);
                myAdapter.notifyDataSetChanged();
            }
            @Override
            public void onPullUpToRefresh(PullToRefreshBase pullToRefreshBase) {
                page++;
                getmoredate(page);
                pullToRefreshListView.onRefreshComplete();
            }
        });

    }
    private class MyAdapter extends BaseAdapter {
        private LayoutInflater mInflater;
        private Context context;

        public MyAdapter(Context context) {
            this.context = context;
            mInflater=LayoutInflater.from(context);
        }

        //        public MyAdapter(Context context){
//            mInflater=LayoutInflater.from(context);
//        }

        @Override
        public int getCount() {
            return list.size();
        }

        @Override
        public Object getItem(int i) {
            return list.get(i);
        }

        @Override
        public long getItemId(int i) {
            return 0;
        }

        @Override
        public View getView(int i, View view, ViewGroup viewGroup) {
            ViewHolder viewHolder = null;
            if (view==null){
                viewHolder=new ViewHolder();
                view=mInflater.inflate(R.layout.item,null);
                viewHolder.title=view.findViewById(R.id.item_textview);
                viewHolder.content = view.findViewById(R.id.item_content);
                viewHolder.imageView=view.findViewById(R.id.item_img);

                view.setTag(viewHolder);
            }else {
                viewHolder= (ViewHolder) view.getTag();
            }

            viewHolder.title.setText(list.get(i).getTitle());
            viewHolder.content.setText(list.get(i).getCollect_num());
            Picasso.with(context).load(list.get(i).getPic()).into(viewHolder.imageView);

            return view;


        }
        class ViewHolder{
            TextView title;
            TextView content;
            ImageView imageView;
        }
    }

    public void getdata(int page){
        RequestQueue requestQueue= Volley.newRequestQueue(this);
        StringRequest stringRequest=new StringRequest(Request.Method.GET,
                url + page,
                new Response.Listener() {
                    @Override
                    public void onResponse(String response) {
                        Gson gson=new Gson();
                        Bean bean=gson.fromJson(response,Bean.class);
                        list=bean.getData();
                        pullToRefreshListView.setAdapter(myAdapter);
                        pullToRefreshListView.onRefreshComplete();

                    }
                }, new Response.ErrorListener() {
            @Override
            public void onErrorResponse(VolleyError error) {

            }
        });
        requestQueue.add(stringRequest);
    }

    public void getmoredate(int page){
        RequestQueue requestQueue=Volley.newRequestQueue(this);
        StringRequest stringRequest=new StringRequest(Request.Method.GET,
                url + page, new Response.Listener() {
            @Override
            public void onResponse(String response) {
                Gson gson=new Gson();
                Bean bean = gson.fromJson(response, Bean.class);
                list.addAll(bean.getData());
                myAdapter.notifyDataSetChanged();
                pullToRefreshListView.onRefreshComplete();
            }
        }, new Response.ErrorListener() {
            @Override
            public void onErrorResponse(VolleyError error) {

            }
        });
        requestQueue.add(stringRequest);
    }
}

-----------------------------------------------------------------------------------

public class DataBean {

    private String title;
    String Pic;
    String Name;
    String num;

    @Generated(hash = 1626917387)
    public DataBean(String title, String Pic, String Name, String num) {
        this.title = title;
        this.Pic = Pic;
        this.Name = Name;
        this.num = num;
    }

    @Generated(hash = 908697775)
    public DataBean() {
    }

    public String getTitle() {
        return title;
    }

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

    public String getPic() {
        return Pic;
    }

    public void setPic(String pic) {
        Pic = pic;
    }

    public String getName() {
        return Name;
    }

    public void setName(String name) {
        Name = name;
    }

    public String getNum() {
        return num;
    }

    public void setNum(String num) {
        this.num = num;
    }
}

----------------------------------------------------------------------

public class MyApp extends Application {
    static DaoSession daoSession;
    @Override
    public void onCreate() {
        super.onCreate();
        DaoMaster.DevOpenHelper devOpenHelper=new DaoMaster.DevOpenHelper(getApplicationContext(),"My.db");
        Database writableDatabase = devOpenHelper.getWritableDb();
        daoSession=new DaoMaster(writableDatabase).newSession();
    }
    public static DaoSession getdaosession(){
        return daoSession;
    }
}

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xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity">

    <Button
        android:id="@+id/b1"
        android:layout_width="match_parent"
        android:layout_height="50dp"
        android:text="添加到数据库"/>
    <Button
        android:id="@+id/b2"
        android:layout_width="match_parent"
        android:layout_height="50dp"
        android:text="展示数据库数据"
        android:layout_below="@id/b1"/>
    <com.handmark.pulltorefresh.library.PullToRefreshListView
        android:id="@+id/My_Pt"
        android:layout_width="match_parent"
        android:layout_height="400dp"
        android:layout_below="@id/b2">

    com.handmark.pulltorefresh.library.PullToRefreshListView>

RelativeLayout>

<uses-permission android:name="android.permission.INTERNET"/>
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>
<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE"/>
implementation 'com.mcxiaoke.volley:library:1.0.19'

implementation 'com.google.code.gson:gson:2.2.4'
implementation 'com.android.support:recyclerview-v7:27.1.1'
implementation 'com.squareup.picasso:picasso:2.3.2'


implementation 'org.greenrobot:greendao:3.2.2'
implementation 'com.github.userswlwork:pull-to-refresh:1.0.0'