Kotlin contains

To find index of substring in this string in Kotlin, call indexOf() method on this string, and pass the substring as argument . String. indexOf() returns an integer representing the index of first occurrence of the match for the given substring.

String is an array of characters. Kotlin Strings are more or less similar to the Java Strings, but with some new add-ons. Following is the syntax to define a string. var str: String = “Hello” //or var str = “Hello” var newString: String = ‘A’ //ERROR var newString: String = 2 //ERROR .

Using isDigit() and all() Here, we check if each character of a String is a numeric digit. The all method returns true if all characters return true when passed to the isDigit method.

Check whether a string contains a substring in Kotlin

To read a line of string in Kotlin, you can use readline() function .

To filter characters in a String in Kotlin, use String. filter() method . Given a string str1 , and if we would like to filter the characters of this string using a predicate (some condition) predicate , call filter() method on string str1 and pass the predicate predicate as argument to the method as shown below.