Not really a issue. Just need some help ?

[yashdevelops]

Hey ! Can you help me teach how to implement Folio reader in my app ? I'm getting a crash while opening EPUB books.

This is how I have declared Folio reader in my AndoridManifest.xml file.
<activity android:name="com.folioreader.ui.folio.activity.FolioActivity" android:configChanges="orientation|screenSize" android:label="@string/app_name" android:theme="@style/AppTheme.NoActionBar" />

But my Android studio shows a red sign over folio saying,

1. Class referenced in the manifest, com.folioreader.ui.folio.activity.FolioActivity, was not found in the project or the libraries
2. Unresolved class 'FolioActivity'

2020-07-31 18:16:44.364 28333-28333/? E/AndroidRuntime: FATAL EXCEPTION: main
    Process: com.yashdevelops.nerdystore, PID: 28333
    java.lang.NullPointerException: Attempt to invoke virtual method 'android.content.SharedPreferences android.content.Context.getSharedPreferences(java.lang.String, int)' on a null object reference
        at c.r.a.f.k.<init>(Unknown Source:14)
        at c.r.a.b.t.<init>(Unknown Source:13)
        at c.r.a.c.e.a(:11)
        at i.n.run(Unknown Source:37)
        at android.os.Handler.handleCallback(Handler.java:873)
        at android.os.Handler.dispatchMessage(Handler.java:99)
        at android.os.Looper.loop(Looper.java:193)
        at android.app.ActivityThread.main(ActivityThread.java:6719)
        at java.lang.reflect.Method.invoke(Native Method)
        at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:495)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:858)