[Q] Exception: Fragment already active - Android Q&A, Help & Troubleshooting

Hi!
I have a problem... again
In my layout I have a container which I want to replace with
a) a Google map view
b) a text view
This must be configurable by a settings fragment. Everything works fine. But every time I switch from text to map or visa verse my app crashes with an exception.
java.lang.IllegalStateException: Fragment already active
I don't know what I am doing wrong. After switching from map to text within my settings I call this getMainActivity().setView() method:
Code:
protected void setView(boolean setMap) {
if (setMap == true) {
Log.i(TAG, "Inflating Google Maps fragment");
// Get a new Fragment Manager
fm = getFragmentManager();
FragmentTransaction fta = fm.beginTransaction();
// New instance if none exists
if (this.fragmentMap == null)
{
Log.d(TAG, "map fragment is null");
this.fragmentMap = new FragmentMap();
}
// Ok... if the fragment is not already added we will do it here right now
if (!this.fragmentMap.isAdded())
{
Log.d(TAG, "map fragment not added yet");
// Create a new bundle for the fragment
Bundle args = new Bundle();
this.fragmentMap.setArguments(args);
fta.replace(R.id.container, this.fragmentMap).commit();
} else
{
fta.show(this.fragmentMap).commit();
}
this.useMap = true;
} else if (setMap == false) {
Log.i(TAG, "Inflating text fragment");
// Get a new Fragment Manager
fm = getFragmentManager();
FragmentTransaction fta = fm.beginTransaction();
// New instance if none exists
if (this.fragmentText == null)
{
Log.d(TAG, "textfragment is null");
this.fragmentText = new FragmentText();
}
// Ok... if the fragment is not already added we will do it here right now
if (this.fragmentText != null)
{
// Create a new bundle for the fragment
Bundle args = new Bundle();
Log.d(TAG, "textfragment not yet added");
this.fragmentText.setArguments(args);
fta.replace(R.id.container, this.fragmentText).commit();
} else
{
fta.show(this.fragmentText).commit();
}
this.useMap = false;
}
}
The last messages I get before the exception is thrown are the "....fragment not yet added" messages.
How can I switch between a map fragment and a text fragment?
Thorsten