Null Pointer exception passing data from activity to Fragment

问题

I have the url value in the MainActivity page and i need to pass this url value from ACtivity to Fragment. But when i click the button i'm getting null exception on the line of String url=getArguments().getString("btn_url");

Activity:

 Fragment fragment=new About();                             
        if (fragment != null) {

     FragmentTransaction transaction = getFragmentManager().beginTransaction();
       transaction.replace(R.id.frame_container, fragment, "TAG_FRAGMENT");
        transaction.addToBackStack(null);
        transaction.commit(); 

          Bundle bundle=new Bundle();
          bundle.putString("btn_url", URL);
About fragobj=new About();
     fragobj.setArguments(bundle);
    }

Fragment:

String url=getArguments().getString("btn_url");

回答1:

You need to commit after you set the fragments arguments. Change your code to this:

About fragobj=new About();    
Bundle bundle=new Bundle();
bundle.putString("btn_url", URL);        
fragobj.setArguments(bundle);
getFragmentManager().beginTransaction();
.replace(R.id.frame_container, fragobj, "TAG_FRAGMENT");
.addToBackStack(null);
.commit(); 

来源：https://stackoverflow.com/questions/27247065/null-pointer-exception-passing-data-from-activity-to-fragment