on a null object reference. Attempt to invoke virtual method 'void android.app.ActionBar.setDisplayHomeAsUpEnabled(boolean)'

after convert my application to library (module) and merge it with another App ... When I start activities of the app it crashes. I tried a lot but I don't know how to solve it.

I created an android project (Project A) and inside it I imported another project (Project B (full App but convert it to module)) .

This is the error

    D/AndroidRuntime: Shutting down VM
E/AndroidRuntime: FATAL EXCEPTION: main
    Process: com.project.fullapp, PID: 18007
    java.lang.RuntimeException: Unable to resume activity {com.project.fullapp/com.myapplication.testing.activity}: java.lang.NullPointerException: Attempt to invoke virtual method 'boolean android.app.ActionBar.isShowing()' on a null object reference
        at android.app.ActivityThread.performResumeActivity(ActivityThread.java:5230)
        at android.app.ActivityThread.handleResumeActivity(ActivityThread.java:5269)
        at android.app.servertransaction.ResumeActivityItem.execute(ResumeActivityItem.java:54)
        at android.app.servertransaction.ActivityTransactionItem.execute(ActivityTransactionItem.java:45)
        at android.app.servertransaction.TransactionExecutor.executeLifecycleState(TransactionExecutor.java:176)
        at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:97)
        at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2438)
        at android.os.Handler.dispatchMessage(Handler.java:106)
        at android.os.Looper.loopOnce(Looper.java:226)
        at android.os.Looper.loop(Looper.java:313)
        at android.app.ActivityThread.main(ActivityThread.java:8669)
        at java.lang.reflect.Method.invoke(Native Method)
        at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:571)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1135)
     Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'boolean android.app.ActionBar.isShowing()' on a null object reference
        at com.myapplication.testing.activity.onResume(activity.java:774)
        at android.app.Instrumentation.callActivityOnResume(Instrumentation.java:1476)
        at android.app.Activity.performResume(Activity.java:8441)
        at android.app.ActivityThread.performResumeActivity(ActivityThread.java:5200)
        at android.app.ActivityThread.handleResumeActivity(ActivityThread.java:5269) 
        at android.app.servertransaction.ResumeActivityItem.execute(ResumeActivityItem.java:54) 
        at android.app.servertransaction.ActivityTransactionItem.execute(ActivityTransactionItem.java:45) 
        at android.app.servertransaction.TransactionExecutor.executeLifecycleState(TransactionExecutor.java:176) 
        at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:97) 
        at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2438) 
        at android.os.Handler.dispatchMessage(Handler.java:106) 
        at android.os.Looper.loopOnce(Looper.java:226) 
        at android.os.Looper.loop(Looper.java:313) 
        at android.app.ActivityThread.main(ActivityThread.java:8669) 
        at java.lang.reflect.Method.invoke(Native Method) 
        at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:571) 
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1135) 

this from activity

boolean showActionBar = settings.getBoolean(Preferences.KEY_SHOW_ACTION_BAR, true);
    ActionBar bar = getActionBar();
    if (showActionBar && (bar.isShowing() != showActionBar))
    bar.show();
    else if (!showActionBar && (bar.isShowing() != showActionBar))
        bar.hide();


    bannerView.getbannerBox().setActionBarReplacementVisible(!showActionBar);
   banneView.setOnbannerboxListener(this);
   banneView.setOnInputListener(this);
    updateUndoRedoIcons();
    setKeepScreenOn();
    banne.startInput();
}

manifest module

<application
    android:allowBackup="true"
    android:hardwareAccelerated="true"
    android:icon="@drawable/icon_logo"
    android:roundIcon="@drawable/icon_logo"
    android:label="@string/app_name"
    android:largeHeap="true"
    android:theme="@style/AppTheme"
    tools:replace="android:label,android:icon,android:theme">
    <activity
        android:exported="true"
        android:theme="@style/AppTheme.Splash"
        android:name=".Splash">
        <intent-filter>
            <category android:name="android.intent.category.MULTIWINDOW_LAUNCHER" />
            <action android:name="android.intent.action.MAIN" />
            <category android:name="android.intent.category.LAUNCHER" />


        </intent-filter>
    </activity>


    <activity
        android:name="com.myapplication.testing.activity"
        android:label="@string/app_name"
        android:theme="@style/AppTheme">
    </activity>
...
</application> 

manifest the App

<application
    android:fullBackupContent="false"
    android:allowBackup="true"
    android:name="com.project.fullapp"
    android:icon="@mipmap/ic_launcher"
    android:label="@string/app_name"
    android:supportsRtl="true"
    android:theme="@style/AppTheme"
    tools:replace="android:label,android:icon,android:theme">

    <activity
        android:name="com.myapplication.testing.activity"
        android:label="@string/app_name">
    </activity>
...
    </application>