java - Add new fragment tab to existing tabbed activity on button click in Android -

i have tabbed activity named stage1.java, java class named stage1_fragment , sections_pager_adapter.java.

i want add new fragment tab existing viewpager on floating button clicked without refreshing other tabs.

stage1.java:

public class stage1 extends appcompatactivity implements stage1_fragment.stage1data{  private static final string tag = "stage1";  private sections_pager_adapter msectionspageadapter; private viewpager mviewpager;  private arraylist valuestage1frag;   @override protected void oncreate(bundle savedinstancestate) {     super.oncreate(savedinstancestate);     setcontentview(r.layout.activity_stage1);      toolbar toolbar = (toolbar) findviewbyid(r.id.toolbar_stage1);     setsupportactionbar(toolbar);      msectionspageadapter = new sections_pager_adapter(getsupportfragmentmanager());      mviewpager = (viewpager) findviewbyid(r.id.container_stage1);     setupviewpager(mviewpager);      tablayout tablayout = (tablayout) findviewbyid(r.id.tabs_stage1);     tablayout.setupwithviewpager(mviewpager);      floatingactionbutton fab = (floatingactionbutton) findviewbyid(r.id.fab);     fab.setonclicklistener(new view.onclicklistener() {         @override         public void onclick(view view) {             //add tab on listener         }     });  }   private void setupviewpager(viewpager viewpager){     sections_pager_adapter adapter = new sections_pager_adapter(getsupportfragmentmanager());     adapter.addfragment(new stage1_fragment(), "feasibility study");     adapter.addfragment(new planning_fragment(), "planning");     adapter.addfragment(new alignment_fragment(), "alignment");     adapter.addfragment(new cross_section_fragment(), "cross-section");     viewpager.setadapter(adapter);  }   @override public void sendstage1data(arraylist stage1data) {     valuestage1frag = stage1data;  }} 

sections_pager_adapter.java

public class sections_pager_adapter extends fragmentpageradapter {  private final list<fragment> mfragmentlist = new arraylist<>(); private final list<string> mfragmenttitlelist = new arraylist<>();  public void addfragment(fragment fragment,string title){     mfragmentlist.add(fragment);     mfragmenttitlelist.add(title); }  public sections_pager_adapter(fragmentmanager fm) {     super(fm); }  @override public charsequence getpagetitle(int position){     return mfragmenttitlelist.get(position); }  @override public fragment getitem(int position) {     return mfragmentlist.get(position); }  @override public int getcount() {     return mfragmentlist.size(); } } 

stage1_fragment.java

public class stage1_fragment extends fragment {  private static final string tag = "stage1_fragment"; private button btnstage1next; private stage1data interfaceimplementor; private arraylist<string> sendstage1data;   public interface stage1data{     public void sendstage1data(arraylist senddata); }  @override public void onattach(activity context){     super.onattach(context);     this.interfaceimplementor = (stage1data)context; } @override public view oncreateview(layoutinflater inflater, viewgroup container, bundle savedinstancestate) {     view view = inflater.inflate(r.layout.fragment_stage1, container, false);     return view; } } 

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