E/AndroidRuntime: FATAL EXCEPTION: main
    Process: com.nikita.mozhaev.vocabulary, PID: 11288
    java.lang.RuntimeException: Unable to start activity ComponentInfo{com.nikita.mozhaev.vocabulary/com.nikita.mozhaev.vocabulary.MainActivity}: java.lang.ClassCastException: android.widget.RelativeLayout cannot be cast to androidx.recyclerview.widget.RecyclerView
        at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:3270)
        at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3409)
        at android.app.servertransaction.LaunchActivityItem.execute(LaunchActivityItem.java:83)
        at android.app.servertransaction.TransactionExecutor.executeCallbacks(TransactionExecutor.java:135)
        at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:95)
        at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2016)
        at android.os.Handler.dispatchMessage(Handler.java:107)
        at android.os.Looper.loop(Looper.java:214)
        at android.app.ActivityThread.main(ActivityThread.java:7356)
        at java.lang.reflect.Method.invoke(Native Method)
        at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:492)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:930)
     Caused by: java.lang.ClassCastException: android.widget.RelativeLayout cannot be cast to androidx.recyclerview.widget.RecyclerView
        at com.nikita.mozhaev.vocabulary.MainActivity.onCreate(MainActivity.java:40)
        at android.app.Activity.performCreate(Activity.java:7802)
        at android.app.Activity.performCreate(Activity.java:7791)
        at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1299)
        at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:3245)
        at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3409) 
        at android.app.servertransaction.LaunchActivityItem.execute(LaunchActivityItem.java:83) 
        at android.app.servertransaction.TransactionExecutor.executeCallbacks(TransactionExecutor.java:135) 
        at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:95) 
        at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2016) 
        at android.os.Handler.dispatchMessage(Handler.java:107) 
        at android.os.Looper.loop(Looper.java:214) 
        at android.app.ActivityThread.main(ActivityThread.java:7356) 
        at java.lang.reflect.Method.invoke(Native Method) 
        at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:492) 
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:930)