What is a String?

Despite not yet learning what strings are, we have already dealt with them in the previous chapters.

Let's now discuss what a string is:

In other words, strings are essentially used to store and manipulate text.

Creating a String

Basically, creating a string in Scala means simply creating a variable of the String class:

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// Without type inference
var greeting: String = "Hello, Scala!"
// With type inference
var greeting = "Hello, Scala!"

Once again, we can safely omit specifying the String data type explicitly and rely on type inference. This is especially common with strings in Scala since only a String is typically represented by enclosing text within double quotes "".

Let's illustrate this with an example:

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object Main {
  def main(args: Array[String]): Unit = {
    var greeting = "Hello"
    greeting += "World"
    println(greeting)
  }
}

In this code, greeting initially points to the String object "Hello". When "World" is concatenated, a new String object "Hello World" is created and greeting is updated to refer to this new object. The original "Hello" string remains unmodified in computer memory.

Concatenating Strings

We have just used string concatenation in the example above, but what it really is?

There are several ways to perform it, but the most commonly used approaches are the following:

using the + operator;
using the concat() method of the String.

Here is an example of using both of them:

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object Main {
  def main(args: Array[String]): Unit = {
    val firstName = "Mike"
    val lastname = "Tyson"
    // First approach
    val fullName1 = firstName + " " + lastname
    println(fullName1)
    // Second approach
    val fullName2 = firstName.concat(" ").concat(lastname)
    println(fullName2)
    println(fullName1 == fullName2)  // Verifies that they are equal
  }
}

As you can see, both approaches yield the same result. In fact, using + is just a shorthand for the concat() method.

Array of Strings

Like with all data types, classes and even data structures, we can also create an array of strings in Scala. Here's an example:

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object Main {
  def main(args: Array[String]): Unit = {
    val stringArray = Array("hello", "darkness", "my old", "friend")
    for (item <- stringArray) {
      print(item + " ")  // String concatenation
    }
  }
}

As you can see, everything is simple here. The only difference from the previous array example is that the data type of array elements is String.

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