Example:
String1 = "AbBaCca";
String2 = "bac";
I want to perform a check that String1 contains String2 or not.
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7 Answers
Kotlin has stdlib package to perform certain extension function operation over the string, you can check this method it will check the substring in a string, you can ignore the case by passing true/false value. Refer this link
"AbBaCca".contains("bac", ignoreCase = true)
2 Comments
nyx
and what about the functions find(), findAnyOf() or indexOf()? Is contains() the fastest method to do this?
Aseem Sharma
At the time this question was asked we didn't have such utility methods, also performance depends on the input and size of the string you are using.
The most idiomatic way to check this is to use the in operator:
String2 in String1
This is equivalent to calling contains(), but shorter and more readable.
3 Comments
kotoMJ
This is shorter, but in case you want to make negation, you will need brackets. At least it seems so. And If you have condition with two such checks, there stands to be over-bracketed. Thus sometimes CONTAINS() fit in some situations better than IN.
yole
If you want to make negation, you can write this as
String2 !in String1. You do not need parentheses.
hellcast
This cannot be the correct one if you want to ignore case since it will call default contains.
You can do it by using the "in" - operator, e.g.
val url : String = "http://www.google.de"
val check : Boolean = "http" in url
check has the value true then. :)
1 Comment
Volodymyr T
It's the simpliest way
See the contains method in the documentation.
String1.contains(String2);
Comments
Kotlin has a few different contains function on Strings, see here: https://kotlinlang.org/api/latest/jvm/stdlib/kotlin.text/contains.html.
If you want it to be true that string2 is contained in string1 (ie you want to ignore case), they even have a convenient boolean argument for you, so you won't need to convert to lowercase first.
Comments
For anyone out there like me who wanted to do this for a nullable String, that is, String?, here is my solution:
operator fun String?.contains(substring:String): Boolean {
return if (this is String) {
// Need to convert to CharSequence, otherwise keeps calling my
// contains in an endless loop.
val charSequence: CharSequence = this
charSequence.contains(substring)
} else {
false
}
}
// Uses Kotlin convention of converting 'in' to operator 'contains'
if (shortString in nullableLongString) {
// TODO: Your stuff goes here!
}
Comments
in my case works codingjeremy answer, with littel changes:
operator fun String?.contains(substring: String?): Boolean {
return if (this != null && substring != null) {
val charSequence: CharSequence = this
charSequence.contains(substring)
} else {
false
}
}
1 Comment
SKD
Code need formatting