If I have a string, say,
"Hello, world!"
and a regex equation that is
"world".toRegex()
and I call
"Hello, world!".replace("world".toRegex(), "universe")
I get the resulting string
"Hello, universe!"
This is all working as expected... but what if I wanted to keep a copy of that string I took out? I want to keep a copy of "world" in a variable.
You may use a callback to String#replace() method and assign a variable inside it:
var needle = ""
val result = "Hello, world!".replace("world".toRegex()) { needle = it.value; "universe" }
println("Replacement result: " + result)
println("Found match: " + needle)
Result:
Replacement result: Hello, universe!
Found match: world
See the online Kotlin demo.
You may use a MutableList<String> to hold a list of matches and add the matches found to it:
var needle = mutableListOf<String>()
val result = "Hello, world! This world is too small.".replace("world".toRegex()) { needle.add(it.value); "universe" }
Result:
Replacement result: Hello, universe! This universe is too small.
Found match: [world, world]
See another Kotlin demo.
(\d{1,4})(\d{1,6})?(\d{1,5})? to replace 343434343434343 string to 3434-343434-34343. Any ideas on it?replace, I am using replaceFirst and optional group is because size is variable of the string, it is basically card numberval str = "Hello, world!"
val regex = "world".toRegex()
val matchResult = regex.find(str)
val match = matchResult?.value.orEmpty()
val replaced = str.replace(regex,"universe")
