Kotlin reflection is a powerful tool that can be used for introspection and manipulation. In this post, we'll take a look at what reflection is and how it can be used in Kotlin. We'll also explore the Kotlin Reflection API and see how it can be used to introspect and manipulate Kotlin code.
Reflection is a process of introspection, or inspecting code at runtime. This can be useful for a number of reasons, such as debugging or code generation. Reflection can also be used to dynamically invoke methods or change the values of fields.
In Kotlin, reflection is primarily used for two things:
To use reflection in Kotlin, we need to import the Kotlin reflection API:
import kotlin.reflect.*
With the reflection API imported, we can now start introspecting Kotlin code.
The first thing we can do with the Kotlin reflection API is introspect Kotlin classes. To introspect a Kotlin class, we first need to get a reference to it. We can do this using the ::class
operator:
val klass = MyClass::class
With a reference to the Kotlin class, we can now introspect its structure. For example, we can get the list of all the members of the class:
val members = klass.members
We can also get the list of all the properties of the class:
val properties = klass.properties
And we can get the list of all the functions of the class:
val functions = klass.functions
In addition to introspection, the Kotlin reflection API can also be used for manipulation. For example, we can dynamically create instances of classes:
val klass = MyClass::class
val instance = klass.createInstance()
We can also dynamically invoke methods on classes:
val klass = MyClass::class
val method = klass.getMethod("myMethod")
method.invoke(instance)
And we can change the values of fields:
val klass = MyClass::class
val field = klass.getField("myField")
field.set(instance, "new value")
In this post, we've taken a look at what reflection is and how it can be used in Kotlin. We've also explored the Kotlin Reflection API and seen how it can be used to introspect and manipulate Kotlin code.