How to use MapBox Navigation in android

Question

In my application I want use Navigation between 2 points and for this I used MapBox.
I write below codes, but when click on navigation button show me force close error and close the application!
I used this tutorial : https://docs.mapbox.com/help/tutorials/android-navigation-sdk/

But when click on navigation button, show me force close error.

My codes :

navButton.setOnClickListener{
val options = NavigationLauncherOptions.builder()
                        .directionsRoute(currentRoute)
                        .shouldSimulateRoute(true)
                        .build()
                    NavigationLauncher.startNavigation(this@MainActivity, options)
                }
}

Error :

java.lang.RuntimeException: Unable to start activity ComponentInfo{in.myapp.mapbox/com.mapbox.services.android.navigation.ui.v5.MapboxNavigationActivity}: java.lang.NullPointerException: Attempt to invoke virtual method 'void com.mapbox.services.android.navigation.ui.v5.NavigationView.onCreate(android.os.Bundle)' on a null object reference
        at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:3792)
        at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3968)
        at android.app.servertransaction.LaunchActivityItem.execute(LaunchActivityItem.java:85)
        at android.app.servertransaction.TransactionExecutor.executeCallbacks(TransactionExecutor.java:135)
        at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:95)
        at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2307)
        at android.os.Handler.dispatchMessage(Handler.java:106)
        at android.os.Looper.loop(Looper.java:246)
        at android.app.ActivityThread.main(ActivityThread.java:8506)
        at java.lang.reflect.Method.invoke(Native Method)
        at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:602)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1130)
     Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'void com.mapbox.services.android.navigation.ui.v5.NavigationView.onCreate(android.os.Bundle)' on a null object reference
        at com.mapbox.services.android.navigation.ui.v5.MapboxNavigationActivity.onCreate(MapboxNavigationActivity.java:32)
        at android.app.Activity.performCreate(Activity.java:8198)
        at android.app.Activity.performCreate(Activity.java:8182)
        at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1309)
        at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:3765)

Why show me this error ?! how can I fix it?