How to check if String contains Substring in Kotlin?

Kotlin – Check if String contains Specified String

To check if a string contains specified string in Kotlin, use String.contains() method.

Given a string str1, and if we would like to check if the string str2 is present in the string str1, call contains() method on string str1 and pass the the string str2 as argument to the method as shown below.

str1.contains(str2)

contains() method returns true if the string str2 is present in the string str1, else it returns false.

Example 1 – String contains Specified String

In this example, we will take two strings in str1 and str2, and check if the string str1 contains the string str2 using String.contains() method.

Kotlin Program

fun main(args: Array<String>) {
    val str1 = "abcdef"
    val str2 = "cd"
    val result = str1.contains(str2)
    println("The result of str1.contains(str2) is: " + result)
    if (result) {
        println("String str1 contains the string str2.")
    } else {
        println("String str1 does not contain the string str2.")
    }
}

Output

The result of str1.contains(str2) is: true
String str1 contains the string str2.

Example 2 – Specified String is not in Given String

In this example, we will take two strings in str1 and str2 such that str2 is not present in str1. str1.contains(str2) should return false.

Kotlin Program

fun main(args: Array<String>) {
    val str1 = "abcdef"
    val str2 = "pq"
    val result = str1.contains(str2)
    println("The result of str1.contains(str2) is: " + result)
    if (result) {
        println("String str1 contains the string str2.")
    } else {
        println("String str1 does not contain the string str2.")
    }
}

Output

The result of str1.contains(str2) is: false
String str1 does not contain the string str2.

Conclusion

In this Kotlin Tutorial, we learned how to check if given string contains a specified string value in it, using String.contains() method, with the help of Kotlin example programs.