Null pointer struggling for weeks

Question

this code is giving me a null pointer please help me fix it.

private void homeFragment(Profile profile) {
    if (profile != null) {
        Bundle mBundle = new Bundle();
        mBundle.putParcelable(PARCEL_KEY, profile);
        HomeFragment hf = new HomeFragment();
        hf.setArguments(mBundle);

        FragmentManager fragmentManager = getActivity().getSupportFragmentManager();
        FragmentTransaction fragmentTransaction = fragmentManager
                .beginTransaction();
        fragmentTransaction.replace(R.id.mainContainer, new HomeFragment());
        fragmentTransaction.commit();
    }
}

FragmentManager fragmentManager = getActivity().getSupportFragmentManager(); is the line the logcat is pointing me to please help — Stanley Tutu Dinala, Oct 18 '16 at 20:12
when are you calling this method? maybe getActivity() is returning null — Ariel Carbonaro, Oct 18 '16 at 20:15
Weeks? How is that possible? The stack trace tells you the file and the line at which it happens. A spin through a debugger will tell you what you missed in five minutes. — duffymo, Oct 18 '16 at 20:16
java.lang.NullPointerException: Attempt to invoke virtual method 'android.support.v4.app.FragmentManager android.support.v4.app.FragmentActivity.getSupportFragmentManager()' on a null object reference — Stanley Tutu Dinala, Oct 18 '16 at 20:17
getActivity is coming as null. Pls check if this fragment is being called by activity or not. — Sachiin Gupta, Oct 18 '16 at 20:25
getActivity does not appear anywhere else in my code, only just here on this line — Stanley Tutu Dinala, Oct 18 '16 at 20:27
@duffymo im not sure how to Spin through a debbuger, please assist — Stanley Tutu Dinala, Oct 18 '16 at 20:30
You need an IDE. IntelliJ is the best; use Eclipse or NetBeans if you must. — duffymo, Oct 18 '16 at 20:48
Not forgetting Android Studio, which Google recommend. By the way I answered you question ;O) — Jon Goodwin, Oct 18 '16 at 20:50

Jon Goodwin · Accepted Answer · 2016-10-18T22:32:15.670

The code you are writing should be in a class similar to this:

import android.support.v4.app.FragmentActivity;
public class YourFragmentActivity extends FragmentActivity

Then getSupportFragmentManager() is visible without getActivity(), e.g.

getSupportFragmentManager().beginTransaction().replace(R.id.frame_container, mBullet_frag).commit();

You must include the v4 library in the final build (just find it in the sdk and drop it in your project libs folder).

This will work, if you follow all the rules.

Of course it could be you did not intend to use getSupportFragmentManager() but wanted the standard one (getFragmentManager()). In this case you don't need the v4 library, or reference to it.

Null pointer struggling for weeks

1 Answers1