In the documentation for android.support.v4.app.FragmentManager:
\"Static library support version of the framework\'s FragmentManager. Used to write apps that run on
If you are using support Packages in your project or app, then you have to use getSupportFragmentManager because that is how you will return the fragmentManager for interacting with fragments associated with this activity. In the other hand, if you are not, then you can use getFragmentManager. It only depends on what you are using in your app.