MainActivity Database Debugging

MainActivity.kt

// ...
button_database.setOnClickListener { it ->
    val waktuDb: WaktuDb = WaktuDb.getInstance(this@MainActivity)!!
    Observable
            .create<Boolean> { emitter ->
                val strWaktu = SimpleDateFormat("dd-MM-yyyy HH:mm:ss", Locale.US)
                        .format(Date())
                val waktuData = WaktuData(null, strWaktu)
                waktuDb.waktuDao()
                        .insert(waktuData)
                emitter.onNext(true)
                emitter.onComplete()
            }
            .subscribeOn(Schedulers.io())
            .observeOn(AndroidSchedulers.mainThread())
            .subscribe(
                    {
                        Toast.makeText(this@MainActivity, "Data has been saved", Toast.LENGTH_SHORT)
                                .show()
                    },
                    {
                        it.printStackTrace()
                        Toast.makeText(this@MainActivity, "Error occured", Toast.LENGTH_SHORT)
                                .show()
                    },
                    {
                        /* nothing to do in here */
                    }
            )
}
// ...