v4 getFragmentManager with Activity - Incompatible types

Question

I have a simple activity which runs as expected.

import android.app.Activity;
import android.app.FragmentManager;
// import android.support.v4.app.FragmentManager;
import android.os.Bundle;

public class MainActivity extends Activity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        // FragmentManager fm = getSupportFragmentManager(); // ActionBarActivity
        FragmentManager fm = getFragmentManager(); // Activity
    }
}

I then replaced

import android.app.FragmentManager;

with

import android.support.v4.app.FragmentManager;

so I could support my older devices.. However, this reports an error:

Incompatible types.

    Required: android.support.v4.app.FragmentManager

    Found: android.app.FragmentManager

What am I doing wrong here?

The popular solution I found is to use getSupportFragmentManager() instead, but this only works for ActionBarActivites [edit - see answers] and FragmentActivities.

cannot convert from android.app.FragmentManager to android.support.v4.app.FragmentManager

The other relevant solution points to using a FragmentActivity instead, but this appears to have the same legacy problems.

The method getFragmentManager() is undefined for the type MyActivity

import android.support.v4.app.FragmentManager;
import android.os.Bundle;
import android.support.v4.app.FragmentActivity;

    public class MainActivity extends FragmentActivity {
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        //setContentView(R.layout.activity_main);
        // FragmentManager fm = getSupportFragmentManager(); // ActionBarActivity
        FragmentManager fm = getFragmentManager();
    }
}

I'm pretty sure the solution to this will be on SE already, but it isn't easy (for me) to find. The minimal example should help other people with understanding it, too.

• I'm fairly new to Android.

Answer 1

In your first case if you use getSupportFragmentManager() you need to extend FragmentActivity or extend ActionBarActivity (extends FragmentActivity) as FragmentActivity is the base class for support based fragments.

In your second case you need to use getSupportFragmentManager() instead of getFragmentManager().

Fragments were introduced in honeycomb. To support fragments below honeycomb you need to use fragments from the support library in which case you need to extend FragmentActivity and use getSupportFragmentManager().