如何将字符串的某些字符与HashMap的值交换 <String,String> 在科特林？

Question

Assuming I have a

val s: String = "14ABC5"

and have a HashMap

val b: HashMap<String,String> = hashMapOf("A" to "10", "B" to "11", "C" to "12", "D" to "13", "E" to "14", "F" to "15" )

How would I change all occurrences of A,B,C with 10, 11, 12 while keeping their order ("1", "4", "10", "11", "12", "5")?

So far I have this

val result: List<String> = s.toUpperCase().toCharArray().map{ it.toString() }.map{ it -> b.getValue(it)}

which works if ALL characters of the String exist in the HashMap but my String may contain inexistent keys as well.

Answer 1

You could either use getOrDefault(...) , or the Kotlinesque b[it] ?: it .

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_{By the way, if you're using the implicit lambda argument name ( it ), you can get rid of the it -> .}

Answer 2

You can use the String as an iterable by default and simplify your code as follows:

s.map { it.toString() }
 .map { b[it] ?: it }