如何比较类和接口？

有人可以解释我如何比较KClasse-s和接口吗？ 我知道如何检查类或接口是否相同，但我不明白如何检查A类是B类的超类。

interface IB {} interface IC : IB {} open class A {} open class B : A() {} open class C : B(), IC {} fun main(args: Array<String>) { if (B::class == B::class) { println("B class is equal to B class") } if (IB::class == IB::class) { println("IB interface is equal to IB interface") } if (A::class ??? B::class) { println("A class is parent of B class") } if (A::class ??? C::class) { println("A class is superclass of C class") } if (C::class ??? IC) { println("C class is implement IC interface") } if (IC ??? IB) { println("IC interface is implement IB interface") } } 

Answer 1

Kotlin反射没有检索有关KClass层次结构的信息的API，因此检查一个KClass是否是另一个KClass超类或子类的唯一方法是比较相应的Java类：

 interface IB {} interface IC : IB {} open class A {} open class B : A() {} open class C : B(), IC {} fun main(args: Array<String>) { if (B::class == B::class) { println("B class is equal to B class") } if (IB::class == IB::class) { println("IB interface is equal to IB interface") } if (A::class.java.isAssignableFrom(B::class.java)) { println("A class is parent of B class") } if (A::class.java.isAssignableFrom(C::class.java)) { println("A class is superclass of C class") } if (IC::class.java.isAssignableFrom(C::class.java)) { println("C class is implement IC interface") } if (IB::class.java.isAssignableFrom(IC::class.java)) { println("IC interface is implement IB interface") } } 

更新：你也可以定义两个扩展函数，这将使这种检查更好一点：

 inline fun <reified L : Any, reified R : Any> isSubClassOf(): Boolean { return R::class.java.isAssignableFrom(L::class.java) } inline fun <reified L : Any, reified R : Any> isSuperClassOf(): Boolean { return L::class.java.isAssignableFrom(R::class.java) } fun main(args: Array<String>) { if (isSubClassOf<B, B>()) { println("B class is equal to B class") } if (isSubClassOf<IB, IB>()) { println("IB interface is equal to IB interface") } if (isSuperClassOf<A, B>()) { println("A class is parent of B class") } if (isSuperClassOf<A, C>()) { println("A class is superclass of C class") } if (isSubClassOf<C, IC>()) { println("C class is implement IC interface") } if (isSubClassOf<IC, IB>()) { println("IC interface is implement IB interface") } }