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Scala String Operations

By IncludeHelp Last updated : October 20, 2024

A string is a very important datatype in Scala. This is why there are a lot of operations that can be done on the string object. Since the regular operations like addition, subtraction is not valid for a string, therefore, special operations like concatenation, comparison are defined.

In this tutorial, we will share some of the important and common string functions.

1. String Equality (==)

The traditional equality operator == is used to compare two strings. It checks if the values of the two strings are equal and returns a boolean result (true or false).

Syntax

str1 == str2 // returns TRUE or FALSE

Example

val str1 = "Include"
val str2 = "Includes"
val result = str1 == str2  // This will return false
println(result) // Output: false

2. String Length

The length method is used to find the number of characters in a string, including spaces. This method is helpful when you need to traverse or limit operations on a string based on its length.

Syntax

// this outputs a positive integer denoting the 
// number of characters in the array. 
str1.length 

Example

val str1 = "Include help"
println(str1.length) // this will print 12

3. String Concatenate

You can concatenate a string with another string. It means the second string will be appended to the first string.

Syntax

str1.concat(str2)

Example

val str1 = "Include"
val str2 = "Help"
val result = str1.concat(str2)
println(result) // This will print "IncludeHelp"

4. Getting Characters from a String

The charAt() method is used to return the character at a specific index in a string. The index is zero-based, meaning it starts at 0. If the input index is greater than the length of the string, the method will throw an error.

Syntax

str1.charAt(n)

Example

val name = "Include"
name.charAt(4) // This will output 'u'.

5. Finding Characters from a String

The indexOf() method returns the index of the first occurrence of a specified character in a string. It returns an integer, which will be a non-negative value within the length of the string if the character is found, otherwise, it returns -1.

Syntax

str1.indexOf("a")

Example

val name = "Include"
name.indexOf('d') // This will output 5.

6. Extracting Substring from a String

The substring() method is used to extract a part of the string between two specified indices (start index, inclusive; end index, exclusive). The new substring is a portion of the original string.

Syntax

str2 =  str1.substring(startIndex , endIndex)

Example

val name = "IncludeHelp is awesome"
name.substring(14, 21) // This will output "awesome".

Example of Scala String Operations

object MyClass {
      
      def main(args: Array[String]) {
         val str1 = "include Help "
         val str2 = "is awesome"
         
         println("str1 = " + str1)
         println("str2 = " + str2)
         
         println("Comparison between str1 and str2 is " + (str1 == str2))
         println("The length of str1 is " + str1.length)
         println("Concatenating str1 with str2 gives \n " + str1.concat(str2))
         println("The character at  index 5 of str2 is" + str2.charAt(5))
         println("The index of 'c' in str1 is " + str1.indexOf("c"))
      }
   }

Output

str1 = include Help 
str2 = is awesome
Comparison between str1 and str2 is false
The length of str1 is 13
Concatenating str1 with str2 gives 
 include Help is awesome
The character at  index 5 of str2 ise
The index of 'c' in str1 is 2