How to iterate over hashmap in Kotlin?

It's not that difficult:

for ((key, value) in map) {
    println("$key = $value")
}

OR
_{(Updated in accordance with @RuckusT-Boom's and @KenZira's information.)}

 map.forEach { (key, value) -> println("$key = $value") }

For the above answer, be careful with Android below N!

map.forEach { key, value -> println("$key = $value") }

reference to Java 8 api which leads to:

Rejecting re-init on previously-failed class java.lang.Class<T>

map.forEach { (key, value) -> println("$key = $value") }

is Kotlin feature

Another way that has not been mentioned is:

val mapOfItems = hashMapOf(1 to "x", 2 to "y", -1 to "zz")
mapOfItems.map { (key, value) -> println("$key = $value") }

Use 'for loop' or 'forEach' or 'Iterator'

 fun main(args : Array<String>) {
    val items = HashMap<String, String>()
    items["1"] = "USA"
    items["2"] = "Japan"
    items["3"] = "India"

    //for loop example
    println("\n-- Example 1.1 -- ");
    for ((k, v) in items) {
        println("$k = $v")
    }
    // forEach example
    println("\n-- Example 1.2 --");
    items.forEach { (k, v) ->
        println("$k = $v")
    }

    //Iterator example
    println("\n-- Example 1.3 --");
    val itr = items.keys.iterator()
    while (itr.hasNext()) {
        val key = itr.next()
        val value = items[key]
        println("${key}=$value")
    }

}