android - How can I display a listview from a database in a fragment in a drawer navigation activity -

can me please display listview database in fragment (drawer navigation activity)? tried doesn't work in fragment.

this's file fragment3.java

public class fragment3 extends fragment { private string json_string; private listview listview; public static final string url="http://10.0.3.2/scripts/select.php"; public static final string tag_json_array="result"; @nullable @override public view oncreateview(layoutinflater inflater, viewgroup container, bundle savedinstancestate) {     return inflater.inflate(r.layout.fragment3, container, false);         super.oncreate(savedinstancestate);         setcontentview(r.layout.fragment3);         listview = (listview) findviewbyid(r.id.listview);         listview.setonitemclicklistener(this);         getjson();     } private void display(){     jsonobject jsonobject = null;     arraylist<hashmap<string,string>> list = new arraylist<hashmap<string, string>>();     try {         jsonobject = new jsonobject(json_string);         jsonarray result = jsonobject.getjsonarray(tag_json_array);          for(int = 0; i<result.length(); i++){             jsonobject jo = result.getjsonobject(i);             string id= jo.getstring("id");             string name = jo.getstring("name");             string email= jo.getstring("email");              hashmap<string,string> liste= new hashmap<>();             // liste.put("type",type);             liste.put("id",id);             liste.put("email",email);             list.add(liste);         }      } catch (jsonexception e) {         e.printstacktrace();     }      listadapter adapter = new simpleadapter(             fragment3.this, list, r.layout.listview,             new string[]{"id","email"},             new int[]{r.id.id, r.id.name});      listview.setadapter(adapter); }  private void getjson(){     class getjson extends asynctask<void,void,string> {          progressdialog loading;         @override         protected void onpreexecute() {             super.onpreexecute();             loading = progressdialog.show(fragment3.this,"fetching data","wait...",false,false);         }          @override         protected void onpostexecute(string s) {             super.onpostexecute(s);             loading.dismiss();             json_string = s;             display();         }          @override         protected string doinbackground(void... params) {             requesthandler rh = new requesthandler();             string s = rh.sendgetrequest(url);             return s;         }     }     getjson gj = new getjson();     gj.execute(); }  @override public void onitemclick(adapterview<?> parent, view view, int position, long id) {     intent intent = new intent(this, viewuser.class);     hashmap<string,string> map =(hashmap)parent.getitematposition(position);     string tid= map.get("id").tostring();     intent.putextra("type", tid);     startactivity(intent); } 

} in advance