sample of substringAfter method

gistfile1.txt

    private const val FILE_PATH = "/storage/emulated/0/DCIM/Gallery/erwfwet285d9cesdferqwrsdfsg7e3259f.mp4"
    
    fun main() {
        val extension = FILE_PATH.substringAfter(delimiter = ".", missingDelimiterValue = "Extension Not found")
        println("File extension -> $extension")
    }
    
    // Output
    File extension -> mp4
    
    Explanation: the above code successfully give you the mp4 extension name of the file. 
    But if we change the delimiter value to something which does not exist inside the source string 
    then the missingDelimiterValue will be returned which is Extension Not Found.