“unfortunately android app has stopped” with simple swipe tabs

I have a simple program that just shows three swipe tabs. Every time I run it, it gives me the error message as mentioned in the title. I am sharing all the code, including the error report.

This is the log report...

12-25 20:23:44.599  14675-14675/com.example.please.devitti E/AndroidRuntime﹕ FATAL EXCEPTION: main
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.please.devitti/com.example.please.devitti.FragmentAct}: java.lang.NullPointerException
        at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2313)
        at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2365)
        at android.app.ActivityThread.access$600(ActivityThread.java:156)
        at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1344)
        at android.os.Handler.dispatchMessage(Handler.java:99)
        at android.os.Looper.loop(Looper.java:153)
        at android.app.ActivityThread.main(ActivityThread.java:5336)
        at java.lang.reflect.Method.invokeNative(Native Method)
        at java.lang.reflect.Method.invoke(Method.java:511)
        at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:833)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:600)
        at dalvik.system.NativeStart.main(Native Method)
 Caused by: java.lang.NullPointerException
        at com.example.please.devitti.FragmentAct.onCreate(FragmentAct.java:17)
        at android.app.Activity.performCreate(Activity.java:5122)
        at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1081)
        at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2277)
        at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2365)
        at android.app.ActivityThread.access$600(ActivityThread.java:156)
        at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1344)
        at android.os.Handler.dispatchMessage(Handler.java:99)
        at android.os.Looper.loop(Looper.java:153)
        at android.app.ActivityThread.main(ActivityThread.java:5336)
        at java.lang.reflect.Method.invokeNative(Native Method)
        at java.lang.reflect.Method.invoke(Method.java:511)
        at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:833)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:600)
        at dalvik.system.NativeStart.main(Native Method)

This is the manifest...

    <?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://ift.tt/nIICcg"
    package="com.example.please.devitti" >
    <application

    android:allowBackup="true"
    android:icon="@drawable/logo_icon"
    android:label="@string/app_name"
    android:theme="@style/AppTheme" >

    <activity
        android:name="com.example.please.devitti.FragmentAct"
        android:label="@string/app_name" >
        <intent-filter>
            <action android:name="android.intent.action.MAIN" />

            <category android:name="android.intent.category.LAUNCHER" />
        </intent-filter>
    </activity>



    </application>

</manifest>

This is the main Fragment Activity..

    package com.example.please.devitti;

import android.app.ActionBar;
import android.app.FragmentTransaction;
import android.os.Bundle;
import android.support.v4.app.FragmentActivity;


public class FragmentAct extends FragmentActivity implements ActionBar.TabListener{

    ActionBar actionBar;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.fragment_act);
        actionBar = getActionBar();
        actionBar.setNavigationMode(ActionBar.NAVIGATION_MODE_TABS);

        ActionBar.Tab tab1 = actionBar.newTab();
        ActionBar.Tab tab2 = actionBar.newTab();
        ActionBar.Tab tab3 = actionBar.newTab();

        tab1.setText("A");
        tab2.setText("B");
        tab3.setText("C");

        tab1.setTabListener(this);
        tab2.setTabListener(this);
        tab3.setTabListener(this);


        actionBar.addTab(tab1);
        actionBar.addTab(tab2);
        actionBar.addTab(tab3);





    }

    @Override
    public void onTabSelected(ActionBar.Tab tab, FragmentTransaction ft) {

    }

    @Override
    public void onTabUnselected(ActionBar.Tab tab, FragmentTransaction ft) {

    }

    @Override
    public void onTabReselected(ActionBar.Tab tab, FragmentTransaction ft) {

    }
}

This is the XML for the main Fragment Activity...

<android.support.v4.view.ViewPager
    xmlns:android="http://ift.tt/nIICcg"
    xmlns:tools="http://ift.tt/LrGmb4"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity"
    android:id="@+id/pager"/>

These are the java files for the three Fragments..

package com.example.please.devitti;


import android.app.Fragment;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;


/**
 * A simple {@link android.app.Fragment} subclass.
 */
public class FragmentA extends Fragment {


    public FragmentA() {
        // Required empty public constructor
    }


    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        // Inflate the layout for this fragment
        return inflater.inflate(R.layout.fragment_a, container, false);
    }


}



package com.example.please.devitti;


import android.app.Fragment;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;


/**
 * A simple {@link android.app.Fragment} subclass.
 */
public class FragmentB extends Fragment {


    public FragmentB() {
        // Required empty public constructor
    }


    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        // Inflate the layout for this fragment
        return inflater.inflate(R.layout.fragment_b, container, false);
    }


}




package com.example.please.devitti;


import android.app.Fragment;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;


/**
 * A simple {@link android.app.Fragment} subclass.
 */
public class FragmentC extends Fragment {


    public FragmentC() {
        // Required empty public constructor
    }


    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        // Inflate the layout for this fragment
        return inflater.inflate(R.layout.fragment_c, container, false);
    }


}

This is the XML file which is the same for the other 2 as well

   <FrameLayout xmlns:android="http://ift.tt/nIICcg"
        xmlns:tools="http://ift.tt/LrGmb4" android:layout_width="match_parent"
        android:layout_height="match_parent" tools:context="com.example.please.myapplication.FragmentC">

        <!-- TODO: Update blank fragment layout -->
        <TextView android:layout_width="match_parent" android:layout_height="match_parent"
            android:text="hello_blank_fragment" />

    </FrameLayout>