What difference between !! and ? in Kotlin, see below table.
a: String? a.length a?.length a!!.length “cat” Compile-time error 3 3 null Compile-time error null NullPointerException Ref: https://kotlinlang.org/docs/reference/null-safety.html
a: String? a.length a?.length a!!.length “cat” Compile-time error 3 3 null Compile-time error null NullPointerException Ref: https://kotlinlang.org/docs/reference/null-safety.html
The snip code below demonstrates how to extract data from WIFI data which from QRCode