java - Referencing context from a Recycle View Adapter -
i have created recycle view adapter, uses cards. in every card, want dynamically add text views linear layout inside card.
however, cannot code run
here rv adapter:
public class rvadapter extends recyclerview.adapter<rvadapter.eventviewholder>{ context context; list<events> events; calculations calculations = new calculations(); rvadapter(list<events> events){ this.events = events; } @override public int getitemcount() { return events.size(); } @override public eventviewholder oncreateviewholder(viewgroup viewgroup, int i) { view v = layoutinflater.from(viewgroup.getcontext()).inflate(r.layout.card_view, viewgroup, false); eventviewholder pvh = new eventviewholder(v); return pvh; } @override public void onbindviewholder(eventviewholder eventviewholder, int i) { eventviewholder.eventname.settext(events.get(i).getname()); eventviewholder.eventlocation.settext(events.get(i).getlocationname()); eventviewholder.eventdate.settext(calculations.unixtimeconverter(events.get(i).getunixtimestamp())[0]); eventviewholder.eventtime.settext(calculations.unixtimeconverter(events.get(i).getunixtimestamp())[1]); //todo(2):change code dynamically add textviews proper parameters linearlayout; //eventviewholder.eventparticipants.settext(calculations.participantconcatenation(events.get(i).getparticipants())); (string x: events.get(i).getparticipants()) { textview tv=new textview(context); linearlayout.layoutparams params=new linearlayout.layoutparams (linearlayout.layoutparams.wrap_content, linearlayout.layoutparams.wrap_content); params.leftmargin=50; params.topmargin=i*50; tv.settext(x); tv.settextsize((float) 20); tv.setpadding(20, 50, 20, 50); tv.setlayoutparams(params); eventviewholder.eventparticipants.addview(tv) ; } } @override public void onattachedtorecyclerview(recyclerview recyclerview) { super.onattachedtorecyclerview(recyclerview); } public static class eventviewholder extends recyclerview.viewholder { cardview cv; textview eventname; textview eventtime; textview eventlocation; textview eventdate; //todo(1):change type of eventparticipants linear layout; linearlayout eventparticipants; eventviewholder(view itemview) { super(itemview); cv = itemview.findviewbyid(r.id.cardviewitem); eventname = itemview.findviewbyid(r.id.event_name); eventtime = itemview.findviewbyid(r.id.event_time); eventdate = itemview.findviewbyid(r.id.event_date); eventlocation = itemview.findviewbyid(r.id.event_location); eventparticipants = itemview.findviewbyid(r.id.event_participants); } } } the error seems @ place instantiate new textview , pass in context. have tried passing "this" it, causes build time error saying:
textview(android.context.context) in textview cannot applied to(...rvadapter)
i have tried passing a
mainactivity.this , causes build time error saying "mainactivity.this not enclosing class."
if pass in context, causes run time nullpointerexception error:
java.lang.nullpointerexception: attempt invoke virtual method 'android.content.res.resources android.content.context.getresources()' on null object reference @ android.view.viewconfiguration.get(viewconfiguration.java:359) @ android.view.view.<init>(view.java:3587) @ android.view.view.<init>(view.java:3682) @ android.widget.textview.<init>(textview.java:637) @ android.widget.textview.<init>(textview.java:632) @ android.widget.textview.<init>(textview.java:628) @ android.widget.textview.<init>(textview.java:624) @ com.example.android.gatheraround.rvadapter.onbindviewholder(rvadapter.java:56) @ com.example.android.gatheraround.rvadapter.onbindviewholder(rvadapter.java:24) @ android.support.v7.widget.recyclerview$adapter.onbindviewholder(recyclerview.java:6400) @ android.support.v7.widget.recyclerview$adapter.bindviewholder(recyclerview.java:6433) @ android.support.v7.widget.recyclerview$recycler.trybindviewholderbydeadline(recyclerview.java:5377) @ android.support.v7.widget.recyclerview$recycler.trygetviewholderforpositionbydeadline(recyclerview.java:5640) @ android.support.v7.widget.recyclerview$recycler.getviewforposition(recyclerview.java:5482) @ android.support.v7.widget.recyclerview$recycler.getviewforposition(recyclerview.java:5478) @ android.support.v7.widget.linearlayoutmanager$layoutstate.next(linearlayoutmanager.java:2215) @ android.support.v7.widget.linearlayoutmanager.layoutchunk(linearlayoutmanager.java:1542) @ android.support.v7.widget.linearlayoutmanager.fill(linearlayoutmanager.java:1502) @ android.support.v7.widget.linearlayoutmanager.onlayoutchildren(linearlayoutmanager.java:595) @ android.support.v7.widget.recyclerview.dispatchlayoutstep2(recyclerview.java:3625) @ android.support.v7.widget.recyclerview.onmeasure(recyclerview.java:3067) @ android.view.view.measure(view.java:17547) @ android.view.viewgroup.measurechildwithmargins(viewgroup.java:5535) @ android.widget.linearlayout.measurechildbeforelayout(linearlayout.java:1436) @ android.widget.linearlayout.measurehorizontal(linearlayout.java:1083) @ android.widget.linearlayout.onmeasure(linearlayout.java:615) @ android.view.view.measure(view.java:17547) @ android.support.v4.widget.nestedscrollview.measurechildwithmargins(nestedscrollview.java:1417) @ android.widget.framelayout.onmeasure(framelayout.java:436) @ android.support.v4.widget.nestedscrollview.onmeasure(nestedscrollview.java:482) @ android.view.view.measure(view.java:17547) @ android.view.viewgroup.measurechildwithmargins(viewgroup.java:5535) @ android.support.design.widget.coordinatorlayout.onmeasurechild(coordinatorlayout.java:713) @ android.support.design.widget.coordinatorlayout.onmeasure(coordinatorlayout.java:785) @ android.view.view.measure(view.java:17547) @ android.view.viewgroup.measurechildwithmargins(viewgroup.java:5535) @ android.widget.framelayout.onmeasure(framelayout.java:436) @ android.support.v7.widget.contentframelayout.onmeasure(contentframelayout.java:139) @ android.view.view.measure(view.java:17547) @ android.view.viewgroup.measurechildwithmargins(viewgroup.java:5535) @ android.widget.linearlayout.measurechildbeforelayout(linearlayout.java:1436) @ android.widget.linearlayout.measurevertical(linearlayout.java:722) @ android.widget.linearlayout.onmeasure(linearlayout.java:613) @ android.view.view.measure(view.java:17547) @ android.view.viewgroup.measurechildwithmargins(viewgroup.java:5535) @ android.widget.framelayout.onmeasure(framelayout.java:436) @ android.view.view.measure(view.java:17547) @ android.view.viewgroup.measurechildwithmargins(viewgroup.java:5535) @ android.widget.linearlayout.measurechildbeforelayout(linearlayout.java:1436) @ android.widget.linearlayout.measurevertical(linearlayout.java:722) @ android.widget.linearlayout.onmeasure(linearlayout.java:613) @ android.view.view.measure(view.java:17547) @ android.view.viewgroup.measurechildwithmarg 08-15 19:27:17.358 3080-3080/com.example.android.gatheraround i/process: sending signal. pid: 3080 sig: 9 here code main activity , layouts if helps:
public class mainactivity extends appcompatactivity { button eventlistbutton; private bottomsheetbehavior mbottomsheetbehvior; recyclerview rv; linearlayoutmanager llm; context context; public list<events> events; @override protected void oncreate(bundle savedinstancestate) { events = new arraylist<events>(); super.oncreate(savedinstancestate); setcontentview(r.layout.activity_main); //find button eventlistbutton = (button) findviewbyid(r.id.eventlistbutton); //find bottom sheet android.support.v4.widget.nestedscrollview bottomsheet = (android.support.v4.widget.nestedscrollview) findviewbyid(r.id.bottomsheet); //add bottomsheet behavior view mbottomsheetbehvior = bottomsheetbehavior.from(bottomsheet); mbottomsheetbehvior.sethideable(true); mbottomsheetbehvior.setpeekheight(400); mbottomsheetbehvior.setstate(bottomsheetbehavior.state_hidden); eventlistbutton.setonclicklistener(new view.onclicklistener() { @override public void onclick(view view) { if(mbottomsheetbehvior.getstate() == bottomsheetbehavior.state_expanded) { mbottomsheetbehvior.setstate(bottomsheetbehavior.state_collapsed); eventlistbutton.settext("hide"); } else if(mbottomsheetbehvior.getstate() == bottomsheetbehavior.state_collapsed) { mbottomsheetbehvior.setstate(bottomsheetbehavior.state_hidden); eventlistbutton.settext("event list button"); } else if(mbottomsheetbehvior.getstate() == bottomsheetbehavior.state_hidden) { mbottomsheetbehvior.setstate(bottomsheetbehavior.state_expanded); eventlistbutton.settext("peek"); } } }); //bottomsheet callbacks mbottomsheetbehvior.setbottomsheetcallback(new bottomsheetbehavior.bottomsheetcallback() { @override public void onstatechanged(@nonnull view bottomsheet, int newstate) { if (newstate == bottomsheetbehavior.state_expanded) { eventlistbutton.settext("peek"); } else if (newstate == bottomsheetbehavior.state_collapsed) { eventlistbutton.settext("hide"); } else if (newstate == bottomsheetbehavior.state_hidden) { eventlistbutton.settext("event list button"); } } @override public void onslide(@nonnull view bottomsheet, float slideoffset) { } }); //recyler view rv = (recyclerview) findviewbyid(r.id.rv); rv.sethasfixedsize(true); llm = new linearlayoutmanager(context); string[] participants = {"tamim","chiharu","azmain","miyoshi"}; events.add(new events(1302719286,"u22 project",participants,new latlng(37.652832,219.839478),"saizeriya")); events.add(new events(1502419296,"u22 project",participants,new latlng(32.652832,19.839478),"hiroo")); events.add(new events(1901719266,"u22 project",participants,new latlng(19.652832,39.839478),"canada")); events.add(new events(1204219286,"u22 project",participants,new latlng(100.652832,13.839478),"tokyo monorail")); rvadapter adapter = new rvadapter(events); rv.setadapter(adapter); rv.setlayoutmanager(new linearlayoutmanager(context)); } } main activity
<android.support.design.widget.coordinatorlayout xmlns:android="http://schemas.android.com/apk/res/android" xmlns:tools="http://schemas.android.com/tools" xmlns:app="http://schemas.android.com/apk/res-auto" android:id="@+id/bglayout" android:layout_width="match_parent" android:layout_height="match_parent" android:paddingbottom="0dp" android:paddingleft="0dp" android:paddingright="0dp" android:paddingtop="0dp" tools:context=".mainactivity"> <scrollview android:layout_width="match_parent" android:layout_height="match_parent" app:layout_behavior="@string/appbar_scrolling_view_behavior" > <relativelayout android:layout_width="match_parent" android:layout_height="match_parent" > <button android:layout_width="match_parent" android:layout_height="wrap_content" android:layout_margin="8dp" android:text="eventlist button" android:id="@+id/eventlistbutton" /> </relativelayout> </scrollview> <android.support.v4.widget.nestedscrollview android:id="@+id/bottomsheet" android:layout_width="match_parent" android:layout_height="match_parent" android:cliptopadding="true" android:background="@color/recyclerview_background" app:layout_behavior="@string/bottom_sheet_behavior" > <linearlayout android:layout_width="match_parent" android:layout_height="match_parent"> <android.support.v7.widget.recyclerview android:layout_height="match_parent" android:layout_width="match_parent" android:id="@+id/rv" android:layout_marginleft="@dimen/recyclerviewhorizontalpadding" android:layout_marginright="@dimen/recyclerviewhorizontalpadding" > </android.support.v7.widget.recyclerview> </linearlayout> </android.support.v4.widget.nestedscrollview> </android.support.design.widget.coordinatorlayout> and cardview:
<android.support.v7.widget.cardview xmlns:card_view="http://schemas.android.com/apk/res-auto" android:layout_width="match_parent" android:layout_height="wrap_content" xmlns:android="http://schemas.android.com/apk/res/android" xmlns:tools="http://schemas.android.com/tools" android:id="@+id/cardviewitem" card_view:cardcornerradius="@dimen/cardviewcorner" card_view:cardelevation="8dp" card_view:cardbackgroundcolor="@color/cardbackground2" android:layout_margintop="16dp" > <linearlayout android:orientation="vertical" android:layout_width="match_parent" android:layout_height="wrap_content" > <linearlayout android:layout_width="match_parent" android:layout_height="wrap_content" android:orientation="horizontal" android:background="@color/cardbackground" > <textview android:layout_width="0dp" android:layout_height="match_parent" android:layout_weight="2" tools:text="dick museum tour" android:textsize="18sp" android:padding="@dimen/cardmargin" android:textstyle="bold" android:textcolor="@color/white" android:id="@+id/event_name" /> <textview android:layout_height="match_parent" android:layout_width="0dp" android:layout_weight="1" android:textsize="18dp" android:padding="@dimen/cardmargin" android:textstyle="bold" android:textcolor="@color/white" tools:text="8/24" android:textalignment="viewend" android:id="@+id/event_date" /> </linearlayout> <linearlayout android:layout_width="match_parent" android:layout_height="@dimen/card_view_height" android:background="@color/cardbackground2" android:orientation="vertical" > <textview android:layout_width="match_parent" android:layout_height="0dp" android:layout_weight="1" tools:text="time:" android:textcolor="@color/white" android:textsize="18sp" android:gravity="center_vertical" android:paddingleft="@dimen/cardmargin" android:id="@+id/event_time" /> <textview android:layout_width="match_parent" android:layout_height="0dp" android:layout_weight="1" tools:text="location:" android:textcolor="@color/white" android:textsize="18sp" android:gravity="center_vertical" android:paddingleft="@dimen/cardmargin" android:clickable="true" android:id="@+id/event_location" /> <horizontalscrollview android:layout_width="match_parent" android:layout_height="0dp" android:layout_weight="1" > <!--todo(3):update view linear layout--> <linearlayout android:layout_width="match_parent" android:layout_height="match_parent" android:id="@+id/event_participants" android:orientation="horizontal" > </linearlayout> </horizontalscrollview> </linearlayout> </linearlayout> </android.support.v7.widget.cardview> please note have tried version of code use textview instead of linearlayout concatenated names 1 whole string, , worked fine.
i trying create textview every individual name , add linear layout.
this happen because never set context inside adapter. add constructor inside adapter , set context variable.
public class rvadapter extends recyclerview.adapter<rvadapter.eventviewholder> { context context; public rvadapter(context context,...){ this.context = context } } rvadapter adapter = new rvadapter(this,events);
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