47 lines
685 B
Markdown
47 lines
685 B
Markdown
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---
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title: Extension Functions
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---
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# Extension Functions
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Kotlin supports extension functions & extension variables, which allow you to add new functionality to a class without modifying the class itself.
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### Basic Usage
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#### Extension Function
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```kotlin
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fun String.containsSpaces(): Boolean {
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return contains(" ")
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}
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val myString = "Hello World"
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print(myString.containsSpaces())
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```
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Output:
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```shell
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true
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```
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#### Extension Variable
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```kotlin
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val <T> List<T>.lastIndex: Int
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get() = size - 1
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val myList = listOf(1,2,3,4,5)
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print(myList.lastIndex)
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```
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Output:
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```shell
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4
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```
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#### Resources
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* [Kotlin Extensions](https://kotlinlang.org/docs/reference/extensions.html)
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