The use of Kotlin generics

1. Kotlin generics are a mechanism that allows type parameters to be specified at compile time, which can improve code reusability and type safety.

1. Kotlin generics use angle brackets (< >) to specify type parameters.
2. Kotlin generics support class generics, interface generics, and method generics.
3. Kotlin generics can be used in classes, functions, interfaces and delegates.
4. Kotlin generics can use multiple type parameters, separated by commas (,).
5. Kotlin generics support covariance and contravariance, which can be achieved using the out and in keywords.
6. Kotlin generics support type inference and type parameters can be omitted.

2. Some links about Kotlin generics:

1. Kotlin generics official documentation: Generics: in, out, where | Kotlin Documentation

2. Detailed explanation of Kotlin generics: https://www.jianshu.com/p/6e2e6f7b8d8c

3. Kotlin generics practical tutorial: https://www.cnblogs.com/lyc88/p/10366831.html

3. The following are some code examples about Kotlin generics:

1. Define a generic class:

class Box<T>(t: T) { var value = t }

2. Define a generic function:

fun <T> boxIn(value: T) = Box(value)

3. Declare an interface using covariance:

interface Source<out T> { fun next(): T }

4. Use contravariance to declare an interface:

interface Comparable<in T> { operator fun compareTo(other: T): Int }

四、The role of reified in generics

In Kotlin, reified keywords are used in generic functions to get the actual type of a generic type. In a normal generic function, the actual type of the generic type cannot be obtained at runtime due to type erasure. However, you can use  reified the keyword to actualize a generic type at compile time and get the actual type of the generic type at runtime.

1. 1、reified Keywords can only be used in generic functions.

2. 2、reified The keyword can be used for both inline and non-inline functions.

3. 3、reified Keyword can be used to get the actual type of a generic type.

4. 4、reified Keywords can be used to determine the actual type of a generic type.

Here are some  reified links about keywords:

1. Kotlin generic reified keyword official documentation: https://kotlinlang.org/docs/type-parameters.html#reified-type-parameters

2. Detailed explanation of Kotlin generic reified keyword: https://www.jianshu.com/p/5f7c7f5d5b8d

Here's an  reified example using keywords:

inline fun <reified T> isInstanceOf(value: Any): Boolean {
    return value is T
}

fun main() {
    val str = "Hello World"
    val result = isInstanceOf<String>(str)
    println(result) // true
}

In the above example, keywords isInstanceOf are used in the function  reified to get  T the actual type of the generic type, and  is operators are used to determine  value whether it is  T an instance of the type. In  main the function, call  isInstanceOf the function and pass in  String the type as the generic parameter, and the final output result is  true.