An example of Abstracting out and calling fragments

Abstracting Fragment Classes

package com.jfyg.bignerdranch.criminalintent.activities;

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

import com.jfyg.bignerdranch.criminalintent.R;


public abstract class SingleFragmentActivity extends FragmentActivity {

    protected abstract Fragment createFragment();

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_fragment);

        FragmentManager fm = getSupportFragmentManager();
        Fragment fragment = fm.findFragmentById(R.id.fragment_container);

        if (fragment == null) {
            fragment = createFragment();
            fm.beginTransaction()
                    .add(R.id.fragment_container, fragment)
                    .commit();
        }
    }
}


/**/

package com.jfyg.bignerdranch.criminalintent.activities;

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

import com.jfyg.bignerdranch.criminalintent.R;
import com.jfyg.bignerdranch.criminalintent.fragments.CrimeFragment;

public class CrimeActivity extends SingleFragmentActivity {

    @Override
    protected Fragment createFragment() {
        return new CrimeFragment();
    }

}