javascript - Can't go between fragments onClick -

i have 2 fragments, fragmenta , fragmentb. have button on layout of fragmenta, want go fragmentb when click button. tried few things doesn't work. have.

this fragmenta.

import android.app.fragmentmanager; import android.app.fragmenttransaction; import android.os.bundle; import android.app.fragment; //import android.support.v4.app.fragmentmanager; import android.view.layoutinflater; import android.view.view; import android.view.viewgroup; import android.widget.button;   /**  * simple {@link fragment} subclass.  */ public class fragmenta extends fragment implements view.onclicklistener {      button button;     view v;      @override     public view oncreateview(layoutinflater inflater, viewgroup container,                              bundle savedinstancestate) {         // inflate layout fragment         v = inflater.inflate(r.layout.fragment_a, container, false);         return v;     }      @override     public void onactivitycreated(bundle savedinstancestate) {         super.onactivitycreated(savedinstancestate);         button= (button) getactivity().findviewbyid(r.id.clickme);     }      @override     public void onclick(view v) {         fragment fragment = new fragmentb();         fragmentmanager fragmentmanager = getfragmentmanager();;         fragmenttransaction fragmenttransaction = fragmentmanager.begintransaction();         fragmenttransaction.replace(r.layout.activity_main, fragment, fragment.tostring());         fragmenttransaction.addtobackstack(fragment.tostring());         fragmenttransaction.commit();     } } 

this fragmentb.

import android.app.activity; import android.content.intent; import android.net.uri; import android.os.bundle; import android.app.fragment; import android.view.layoutinflater; import android.view.view; import android.view.viewgroup; import android.widget.textview;   public class fragmentb extends fragment {      textview textview;     view v;      @override     public view oncreateview(layoutinflater inflater, viewgroup container, bundle savedinstancestate) {         v = inflater.inflate(r.layout.fragment_b, container, false);         return v;     }      @override     public void onactivitycreated(bundle savedinstancestate) {         super.onactivitycreated(savedinstancestate);         textview= (textview) getactivity().findviewbyid(r.id.textview);     } } 

this fragment_a.xml button inside it.

<framelayout xmlns:android="http://schemas.android.com/apk/res/android"     xmlns:tools="http://schemas.android.com/tools" android:layout_width="match_parent"     android:layout_height="match_parent" tools:context="net.cairobus.communication.fragmenta">      <!-- todo: update blank fragment layout -->      <button         android:layout_width="wrap_content"         android:layout_height="wrap_content"         android:text="new button"         android:id="@+id/clickme"         android:layout_gravity="center" /> </framelayout> 

i can't figure out why won't work

button.setonclicklistener(this);

put below

button= (button) getactivity().findviewbyid(r.id.clickme);