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How to check if a string contains a specific substring in Kotlin

How to check if a string contains a specific substring in Kotlin.

Here's a step-by-step tutorial on how to check if a string contains a specific substring in Kotlin.

Step 1: Initialize the string​

First, you need to initialize the string that you want to check for a substring. You can do this by assigning a value to a variable of type String. For example:

val str = "Hello, World!"

In this example, the string "Hello, World!" is assigned to the variable str.

Step 2: Check if the string contains a substring using the contains function​

Kotlin provides a built-in function called contains that can be used to check if a string contains a specific substring. This function returns a boolean value (true or false) indicating whether the string contains the substring or not.

To use the contains function, you need to call it on the string variable and pass the substring as an argument. Here's an example:

val substring = "Hello"
val containsSubstring = str.contains(substring)

In this example, the contains function is called on the str variable, passing the substring variable as an argument. The result is stored in the containsSubstring variable.

Step 3: Check the result​

After calling the contains function, you can check the result to determine if the string contains the substring or not. You can use an if statement to perform different actions based on the result.

Here's an example:

if (containsSubstring) {
    println("The string contains the substring.")
} else {
    println("The string does not contain the substring.")
}

In this example, if the containsSubstring variable is true, the message "The string contains the substring." will be printed. Otherwise, the message "The string does not contain the substring." will be printed.

By default, the contains function performs a case-sensitive search. If you want to perform a case-insensitive search, you can use the contains function with the ignoreCase parameter set to true.

Here's an example:

val caseInsensitiveSubstring = "hello"
val containsCaseInsensitiveSubstring = str.contains(caseInsensitiveSubstring, ignoreCase = true)

In this example, the contains function is called with the ignoreCase parameter set to true. This means that the search for the substring will be case-insensitive.

That's it! You now know how to check if a string contains a specific substring in Kotlin. You can use the contains function and the result to perform different actions based on whether the string contains the substring or not.