java - I am receiving NullPointerException error after changing an activity to a fragment -
this question has answer here:
- what nullpointerexception, , how fix it? 12 answers
below logcat error getting, json_string = getactivity().getintent().getextras().getstring( "json_data" );
09-10 21:56:07.507 22129-22129/com.example.aids.a09application e/androidruntime: fatal exception: main process: com.example.aids.a09application, pid: 22129 java.lang.nullpointerexception: attempt invoke virtual method 'java.lang.string android.os.bundle.getstring(java.lang.string)' on null object reference @ com.example.aids.a09application.displaylistview.oncreateview(displaylistview.java:31) @ android.support.v4.app.fragment.performcreateview(fragment.java:2192) @ android.support.v4.app.fragmentmanagerimpl.movetostate(fragmentmanager.java:1299) @ android.support.v4.app.fragmentmanagerimpl.movefragmenttoexpectedstate(fragmentmanager.java:1528) @ android.support.v4.app.fragmentmanagerimpl.movetostate(fragmentmanager.java:1595) @ android.support.v4.app.backstackrecord.executeops(backstackrecord.java:758) @ android.support.v4.app.fragmentmanagerimpl.executeops(fragmentmanager.java:2363) @ android.support.v4.app.fragmentmanagerimpl.executeopstogether(fragmentmanager.java:2149) @ android.support.v4.app.fragmentmanagerimpl.optimizeandexecuteops(fragmentmanager.java:2103) @ android.support.v4.app.fragmentmanagerimpl.execpendingactions(fragmentmanager.java:2013) @ android.support.v4.app.fragmentmanagerimpl$1.run(fragmentmanager.java:710) @ android.os.handler.handlecallback(handler.java:751) @ android.os.handler.dispatchmessage(handler.java:95) @ android.os.looper.loop(looper.java:154) @ android.app.activitythread.main(activitythread.java:6692) @ java.lang.reflect.method.invoke(native method) @ com.android.internal.os.zygoteinit$methodandargscaller.run(zygoteinit.java:1468) @ com.android.internal.os.zygoteinit.main(zygoteinit.java:1358) this fragment below lead fragment displayinlistview, using fragment transaction found @ bottom of code. intent displayinlistview activity, have changed fragment, due navigation drawer.
public class standingslist extends fragment implements view.onclicklistener { //make member variable views button mbutton; button mbutton1; textview mresult; string json_response; string json_string; fragmenttransaction fragmenttransaction; progressdialog mprogressdialog; @override public view oncreateview(layoutinflater inflater, viewgroup container, bundle savedinstancestate) { // inflate layout fragment view view = inflater.inflate( r.layout.fragment_standings, container, false ); //get reference of views mbutton = (button) view.findviewbyid( r.id.button ); mbutton1 = (button) view.findviewbyid( r.id.buttontwo ); mresult = (textview) view.findviewbyid( r.id.result ); mbutton1.setonclicklistener(this); //when button clicked mbutton.setonclicklistener( new view.onclicklistener() { @override public void onclick(view view) { //call getjsonresponse method , fetch response server new getjsonresponse().execute(); } } ); return view; } public class getjsonresponse extends asynctask<void, void, string> { string serverurl; public getjsonresponse() { mprogressdialog = new progressdialog( getactivity() ); mprogressdialog.setmessage( "please wait" ); mprogressdialog.settitle( "processing" ); mprogressdialog.setcancelable( false ); } @override protected void onpreexecute() { //set url have fetch json response // not add real ip. serverurl = "http://xx.xx.xx.xx/get_info.php"; mprogressdialog.show(); } @override protected string doinbackground(void... params) { try { url url = new url( serverurl ); httpurlconnection httpurlconnection = (httpurlconnection) url.openconnection(); inputstream inputstream = httpurlconnection.getinputstream(); bufferedreader bufferedreader = new bufferedreader( new inputstreamreader( inputstream ) ); stringbuilder stringbuilder = new stringbuilder(); while ((json_response = bufferedreader.readline()) != null) { stringbuilder.append( json_response + "\n" ); } inputstream.close(); bufferedreader.close(); httpurlconnection.disconnect(); return stringbuilder.tostring().trim(); } catch (malformedurlexception e) { log.e( tag, "malformedurlexception: " + e ); //print exception message log } catch (ioexception e) { log.e( tag, "ioexception: " + e ); //print exception message log } return null; } @override protected void onprogressupdate(void... values) { super.onprogressupdate( values ); } @override protected void onpostexecute(string result) { //set result returned doinbackground() method result textview mresult.settext( result ); mprogressdialog.dismiss(); json_string = result; } } public void onclick(view view){ switch (view.getid()) { case r.id.buttontwo: fragmenttransaction = getfragmentmanager().begintransaction(); fragmenttransaction.replace( main_container, new displaylistview()); fragmenttransaction.commit(); break; } } } this class error is, on line 31 - json_string = getactivity().getintent().getextras().getstring( "json_data" );
this error has been created since converted class fragment activity.
public class displaylistview extends fragment { string json_string; jsonobject jsonobject; jsonarray jsonarray; standingsadapter standingsadapter; listview listview; @override public view oncreateview(layoutinflater inflater, viewgroup container, bundle savedinstancestate) { // inflate layout fragment view view = inflater.inflate( r.layout.display_list_view_layout, container, false ); listview= (listview) view.findviewbyid( r.id.listviewparse ); standingsadapter = new standingsadapter(getactivity(),r.layout.row_layout); listview.setadapter( standingsadapter ); json_string = getactivity().getintent().getextras().getstring( "json_data" ); try { jsonarray = new jsonobject(json_string).getjsonarray("server_response"); int count = 0; int driver_id, team_id, position, points; string firstname, lastname; while(count<jsonarray.length()) { jsonobject jo = jsonarray.getjsonobject(count); driver_id = jo.getint( "driver_id" ); team_id =jo.getint( "team_id" ); firstname = jo.getstring( "first_name" ); lastname= jo.getstring( "last_name" ); position= jo.getint( "position" ); points = jo.getint( "points" ); standings standings = new standings(driver_id, team_id, firstname, lastname, position, points ); standingsadapter.add( standings ); count++; } } catch (jsonexception e) { e.printstacktrace(); } return view; } }
now, have replaced activity new fragment.so have pass data argument.you can mention in below code.
bundle bundle = new bundle(); bundle.putstring(constants.string_json, json_string); replacefragment(displaylistview.newinstance(bundle)); now,you have json_string in actual fragnent ad below.
public static displaylistview newinstance(bundle bungle) { displaylistview fragment = new displaylistview(); fragment.setarguments(bungle); return fragment;} you can retrieve value arguments in oncreate method of fragment below
string json_string = getarguments().getstring(constants.string_json); 
Comments
Post a Comment