constructor with class parameter in Kotlin

Question

I want to have Kotlin class with constructor and get another class as parameter like this.

class LogHelper(cls : class) { }

I had the same class in java and I didn't have any problem with it.

public LogHelper(Class cls) { LOG_TAG = cls.getSimpleName(); }

class is a keyword, Class is a Java class. Class names typically start with a capital letter even in Kotlin. — Eugen Pechanec
– Eugen Pechanec, Commented Mar 10, 2019 at 12:09

Sergio · Accepted Answer · 2019-03-10 12:31:41Z

3

You can use constructor with java.lang.Class parameter:

class LogHelper(cls: Class<*>) { val LOG_TAG = cls.simpleName }

or Kotlin's KClass:

class LogHelper(cls: KClass<*>) { ... }

* - Star Projection, used to indicate we have no information about a generic argument.

Kotlin does not allow raw generic types (e.g. Class), you always have to specify the type parameter (e.g. Class<*>, Class<Any>, Class<SomeClass>).

edited Mar 10, 2019 at 12:31

answered Mar 10, 2019 at 12:04

Sergio

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4 Comments

Yoshimitsu Over a year ago

Thanks for your answer. the right answer for my question was KClass<*> and I find out because of your suggestion. Please add it in your answer.

Salem Over a year ago

@Alishatergholi it may be worth mentioning that raw types are heavily discouraged even in Java.

Yoshimitsu Over a year ago

@Moira do you have any link to explain when we should use raw type.

Salem Over a year ago

@Alishatergholi if possible, never. They are not type safe.

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