Android fragment activity change content after change page -

i have fragment activity have view pager, want every changing page content change programmatically. `

package com.idroid.splashscreen;  import android.os.bundle; import android.support.v4.app.fragment; import android.support.v4.app.fragmentactivity; import android.support.v4.app.fragmentmanager; import android.support.v4.app.fragmentstatepageradapter; import android.support.v4.view.pageradapter; import android.support.v4.view.viewpager; import android.support.v4.view.viewpager.onpagechangelistener; import android.widget.textview; import android.widget.toast;  public class screenslidepageractivity extends fragmentactivity {      private static final int num_pages = 5;     private viewpager mpager;     private pageradapter mpageradapter;     @override     protected void oncreate(bundle savedinstancestate) {         super.oncreate(savedinstancestate);         setcontentview(r.layout.activity_screen_slide);         mpager = (viewpager) findviewbyid(r.id.pager);         mpageradapter = new screenslidepageradapter(getsupportfragmentmanager());         mpager.setadapter(mpageradapter);         onpagechangelistener pagechangelistener=null;           pagechangelistener = new onpagechangelistener() {             @override             public void onpagescrollstatechanged(int arg0) { }              @override             public void onpagescrolled(int arg0, float arg1, int arg2) { }              @override             public void onpageselected(int position) {                  toast.maketext(getapplicationcontext()                          .getapplicationcontext(),                           "page "+position,                          toast.length_long).show();                 textview txt=(textview) findviewbyid(r.id.txtcoba);                txt.settext("page "+position);              }         };         mpager.setonpagechangelistener(pagechangelistener);      }      @override     public void onbackpressed() {         if (mpager.getcurrentitem() == 0) {            super.onbackpressed();         } else {             mpager.setcurrentitem(mpager.getcurrentitem() - 1);         }     }     private class screenslidepageradapter extends fragmentstatepageradapter {         public screenslidepageradapter(fragmentmanager fm) {             super(fm);          }          @override         public fragment getitem(int position) {              return new screenslidepagefragment();         }          @override         public int getcount() {             return num_pages;         }     }    } 

`

    <?xml version="1.0" encoding="utf-8"?> <scrollview xmlns:android="http://schemas.android.com/apk/res/android"     android:id="@+id/content"     android:layout_width="match_parent"     android:layout_height="match_parent" >      <textview         android:id="@+id/txtcoba"          style="?android:textappearancemedium"         android:padding="16dp"         android:linespacingmultiplier="1.2"         android:layout_width="match_parent"         android:layout_height="wrap_content"         android:text="coba" /> </scrollview> 

i change on page selected method , change content of text view. toast it's work text doesn't change. on page 4 when page 3, page 3 show page. other page not.

what should ? before. screenslidepagefragment class

package com.idroid.splashscreen;

import android.os.bundle; import android.support.v4.app.fragment; import android.view.layoutinflater; import android.view.view; import android.view.viewgroup;    public class screenslidepagefragment extends fragment {      @override     public view oncreateview(layoutinflater inflater, viewgroup container,             bundle savedinstancestate) {          viewgroup rootview = (viewgroup) inflater.inflate(                 r.layout.fragment_screen_slide_page, container, false);          return rootview;     } } 

this fragment_screen_slide_page.xml

    <?xml version="1.0" encoding="utf-8"?> <scrollview xmlns:android="http://schemas.android.com/apk/res/android"     android:id="@+id/content"     android:layout_width="match_parent"     android:layout_height="match_parent" >      <textview         android:id="@+id/txtcoba"          style="?android:textappearancemedium"         android:padding="16dp"         android:linespacingmultiplier="1.2"         android:layout_width="match_parent"         android:layout_height="wrap_content"         android:text="coba" /> </scrollview> 

this activity_screen_slide.xml

    <?xml version="1.0" encoding="utf-8"?> <android.support.v4.view.viewpager     xmlns:android="http://schemas.android.com/apk/res/android"     android:id="@+id/pager"     android:layout_width="match_parent"     android:layout_height="match_parent" /> 

issue trying set textview of fragment layout. per code textview in screenslidepagefragment layout.

remove 'textview' settext in onpageeselcted

change screenslidepagefragment this

 private class screenslidepagefragment extends fragment {      @override     public view oncreateview(layoutinflater inflater, viewgroup container,                              bundle savedinstancestate) {         // inflate layout fragment         view row =  inflater.inflate(r.layout.activity_screen_slide, container, false);          textview txt=(textview) row.findviewbyid(r.id.txtcoba);         txt.settext("page using fragment");         return row;     }   }