Android Development with Kotlin

Star-projections

Because of type erasure, incomplete type information is available at runtime. For example, type parameters of generic types are not available:

    val list = listOf(1,2,3)    println(list.javaClass) // Prints: class java.util.Arrays$ArrayList

This leads to a few problems. We can't perform any checks to verify what types of element List contains:

    /*    Compile time error: cannot check instance of erased type:     List<String>    */    if(collection is List<Int>) {        //...    }

The problem occurs because a check is performed at runtime where information about type parameters is not available. Kotlin, however, as opposed to Java, does not allow us to declare a raw type (a generic type that is not parametrized with a type argument):

 SimpleList<> ...