没有通配符的 Kotlin 泛型到 Java

Question

Example Kotlin class:

class Example {
    private lateinit var creator: (Unit) -> String
}

Equivalent in java will be

class Example {
    Function1<? super Unit, ? super String> creator
}

How can I annotate field creator to avoid using of wildcards?

Answer 1

You can remove wildcards by using @JvmSuppressWildcards :

lateinit var creator: (@JvmSuppressWildcards Unit) -> @JvmSuppressWildcards String

By the way your code won't generete wildcards, so following code is perfectly valid without any annotations:

new Example().setCreator(new Function1<Unit, String>() {
     @Override
     public String invoke(Unit unit) {
         return "Test";
     }
});