Created
October 2, 2019 10:03
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Delegated Properties Example in Kotlin
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| import ExampleDelegates.accumulator | |
| import ExampleDelegates.uppercase | |
| import kotlin.properties.ReadWriteProperty | |
| import kotlin.reflect.KProperty | |
| fun main() { | |
| val person = Person("ala1222", 12) | |
| println(person.name)//ALA1222 | |
| println(person.balance) //12 | |
| person.balance = 30 | |
| println(person.balance)//42 | |
| } | |
| class Person { | |
| var name: String by uppercase() | |
| var balance: Int by accumulator() | |
| constructor(name: String, balance: Int) { | |
| this.name = name | |
| this.balance = balance | |
| } | |
| } | |
| object ExampleDelegates { | |
| public fun uppercase(): ReadWriteProperty<Any?, String> = UpperCase() | |
| public fun accumulator(): ReadWriteProperty<Any?, Int> = Accumulator() | |
| private class UpperCase : ReadWriteProperty<Any?, String> { | |
| private var value: String? = null | |
| public override operator fun getValue(thisRef: Any?, property: KProperty<*>): String { | |
| return value ?: throw IllegalStateException( | |
| "Property ${property.name} should be initialized before get." | |
| ) | |
| } | |
| public override operator fun setValue(thisRef: Any?, property: KProperty<*>, value: String) { | |
| this.value = value.toUpperCase() | |
| } | |
| } | |
| private class Accumulator : ReadWriteProperty<Any?, Int> { | |
| private var value: Int = 0 | |
| public override operator fun getValue(thisRef: Any?, property: KProperty<*>): Int { | |
| return value | |
| } | |
| public override operator fun setValue(thisRef: Any?, property: KProperty<*>, value: Int) { | |
| this.value = this.value.plus(value) | |
| } | |
| } | |
| } | |
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