Android fragment commit already called

I need to replace the snippet when retrieving the data. The data comes to @JavascriptInterface and calls the method.

@JavascriptInterface public void sayHello(String type) { CheatActivity.fTrans.replace(R.id.frgmCont, MainActivity.frag2).commit(); } 

Because In the main activation, the fragment is initially started, I get an error from the header. It is necessary to indicate each time the beginning of the transaction with a fragment

 fTrans = getSupportFragmentManager().beginTransaction(); 

But getSupportFragmentManager () gives an error when used in @JavascriptInterface

If I create a method in MainActivity that will change fragments when called from @JavascriptInterface, then the method must be made static. And getSupportFragmentManager () does not work in this case.

xml

 <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" android:layout_width="match_parent" android:layout_height="match_parent" android:orientation="vertical" android:gravity="center"> <FrameLayout android:id="@+id/frgmCont" android:layout_width="match_parent" android:layout_height="479dp"> </FrameLayout>... 

MainActivity

 public static Fragment1 frag1; public static Fragment2 frag2; public static FragmentTransaction fTrans; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_cheat); frag1 = new Fragment1(); frag2 = new Fragment2(); ... fTrans = getSupportFragmentManager().beginTransaction(); fTrans.replace(R.id.frgmCont, frag1).commit(); 

UPD

 public class JsInterface { Context mContext; JsInterface(Context c) { mContext = c; } @JavascriptInterface public void sayHello(String type) { CheatActivity.fTrans = getSupportFragmentManager().beginTransaction(); CheatActivity.fTrans.replace(R.id.frgmCont, CheatActivity.frag2).commit(); }