Значение Android EditText, заменяющее подсказку

я думаю, ты можешь попробовать эту библиотеку

https://github.com/ChaosLeong/PinView

repositories {
maven {
    jcenter()
}
}

dependencies {
   compile 'com.chaos.view:pinview:1.4.2'
}

XML

<com.chaos.view.PinView
android:id = "@+id/firstPinView"
style = "@style/PinWidget.PinView"
android:layout_width = "wrap_content"
android:layout_height = "wrap_content"
android:cursorVisible = "true"
android:hint = "XXXXXX"
android:inputType = "text"
android:itemBackground = "@mipmap/ic_launcher"
android:padding = "@dimen/common_padding"
android:textColor = "@color/text_colors"
android:textSize = "18sp"
android:textStyle = "bold"
app:cursorColor = "@color/line_selected"
app:cursorWidth = "2dp"
app:hideLineWhenFilled = "true"
app:itemCount = "6"
app:itemHeight = "48dp"
app:itemRadius = "4dp"
app:itemSpacing = "0dp"
app:itemWidth = "48dp"
app:lineColor = "@color/line_colors"
app:lineWidth = "2dp"
app:viewType = "rectangle" />