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ov7a/Main.scala Secret

Created Nov 20, 2018
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MapValue examples for article
import java.util.concurrent.atomic.AtomicInteger
import scala.util.Random
object Main {
def main(args: Array[String]): Unit = {
println("Sample1")
sample1()
println("Sample2")
sample2()
println("Sample3")
sample3()
println("Sample4")
sample4()
println("Sample5")
sample5()
}
def sample1(): Unit = {
val someMap = Map("key1" -> "value1", "key2" -> "value2")
def foo(value: String): String = value + "_changed"
val resultMap = someMap.map { case (k, v) => k -> foo(v) }
val resultMapValues = someMap.mapValues(foo)
println(s"resultMap: $resultMap")
println(s"resultMapValues: $resultMapValues")
println(s"equality: ${resultMap == resultMapValues}")
}
def sample2(): Unit = {
case class ValueHolder(value: String)
val someMap: Map[String, String] = Map("key1" -> "value1", "key2" -> "value2")
def foo(value: String): ValueHolder = ValueHolder(value)
val resultMap: Map[String, ValueHolder] = someMap.map { case (k, v) => k -> foo(v) }
val resultMapValues: Map[String, ValueHolder] = someMap.mapValues(foo)
println(s"resultMap: $resultMap")
println(s"resultMapValues: $resultMapValues")
println(s"equality: ${resultMap == resultMapValues}")
}
def sample3(): Unit = {
case class ValueHolder(value: String, seed: Int)
val someMap = Map("key1" -> "value1", "key2" -> "value2")
def foo(value: String): ValueHolder = ValueHolder(value, Random.nextInt())
val resultMap: Map[String, ValueHolder] = someMap.map { case (k, v) => k -> foo(v) }
val resultMapValues: Map[String, ValueHolder] = someMap.mapValues(foo)
println(s"resultMap: $resultMap")
println(s"resultMapValues: $resultMapValues")
println(s"equality: ${resultMap == resultMapValues}")
println(s"simple assert for resultMap: ${resultMap.head == resultMap.head}")
println(s"simple assert for resultMapValues: ${resultMapValues.head == resultMapValues.head}")
println(s"resultMapValues: $resultMapValues")
println(s"resultMapValues: $resultMapValues")
}
def sample4(): Unit = {
case class ValueHolder(value: String, seed: Int)
val someMap = Map("key1" -> "value1", "key2" -> "value2")
def foo(value: String): ValueHolder = ValueHolder(value, Random.nextInt())
val resultMapValues: Map[String, ValueHolder] = someMap.mapValues(foo).map(identity)
println(s"resultMapValues: $resultMapValues")
println(s"simple assert for resultMapValues: ${resultMapValues.head == resultMapValues.head}")
println(s"resultMapValues: $resultMapValues")
println(s"resultMapValues: $resultMapValues")
}
def sample5(): Unit = {
val someMap1 = Map("key1" -> new AtomicInteger(0), "key2" -> new AtomicInteger(0))
val someMap2 = Map("key1" -> new AtomicInteger(0), "key2" -> new AtomicInteger(0))
def increment(value: AtomicInteger): Int = value.incrementAndGet()
val resultMap: Map[String, Int] = someMap1.map { case (k, v) => k -> increment(v) }
val resultMapValues: Map[String, Int] = someMap2.mapValues(increment)
println(s"resultMap (1): $resultMap")
println(s"resultMapValues (1): $resultMapValues")
println(s"resultMap (2): $resultMap")
println(s"resultMapValues (2): $resultMapValues")
}
}
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