Parameterizedtypereference kotlin

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ParameterizedTypeReference in Kotlin

The ParameterizedTypeReference class in Kotlin is used to capture generic information at runtime. It helps in obtaining details about generic types when dealing with classes that have generic parameters.

Before diving into the details of ParameterizedTypeReference, let’s understand generics in Kotlin with an example:


  // Define a generic class
  class Box<T> {
    var content: T? = null
  }
  
  // Create a box of integers
  val intBox = Box<Int>()
  intBox.content = 10
  val intValue = intBox.content
  
  // Create a box of strings
  val stringBox = Box<String>()
  stringBox.content = "Hello"
  val stringValue = stringBox.content

In the above example, we have a generic class Box which can hold any type of value. We have created instances of Box with specific types – Int and String.

Now, let’s say we want to obtain the generic type information of a class that is passed as a parameter to a method. This is where ParameterizedTypeReference comes into play. Here’s an example:


  // Define a method that takes a generic class as a parameter
  fun <T> processList(list: List<T>, typeReference: ParameterizedTypeReference<List<T>>) {
    // Do some processing based on the generic type information
  }
  
  // Usage of the method with specific types
  val intList: List<Int> = listOf(1, 2, 3)
  processList(intList, object : ParameterizedTypeReference<List<Int>>() {})
  val stringList: List<String> = listOf("a", "b", "c")
  processList(stringList, object : ParameterizedTypeReference<List<String>>() {})

In the above example, we have the processList method that takes a List and a ParameterizedTypeReference as parameters. The ParameterizedTypeReference is created using an anonymous object.

This allows us to capture the generic type information at runtime. Inside the processList method, we can access this information and do some processing accordingly.

By using ParameterizedTypeReference, we can avoid type erasure and retain the generic type information. It is useful in scenarios where we need to work with generic types dynamically.


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