ArrayBuffers
In the following lesson, you will learn about ArrayBuffers and how they differ from ordinary arrays.
We'll cover the following
Introduction
An ArrayBuffer in Scala is a collection that comes under the sequence class. Like Arrays, it is a mutable collection, hence, when elements in an ArrayBuffer are modified, the original ArrayBuffer is updated.
ArrayBuffers are very similar to arrays with the difference that you can add and remove elements from an ArrayBuffer while adding and removing elements is not possible in simple Arrays.
Array methods and operations are also available for ArrayBuffers.
Creating an ArrayBuffer
To be able to use an ArrayBuffer, we first need to import it using the package scala.collection.mutable.ArrayBuffer. Afterward, you can create and populate an ArrayBuffer the same way you create an Array.
import scala.collection.mutable.ArrayBufferval myFirstArrayBuffer = ArrayBuffer(1,2,3,4,5)// Driver CodemyFirstArrayBuffer.foreach(println)
To initialize an ArrayBuffer without populating it, we need to specify the type of element it can store. Mentioning the length is not required as the ArrayBuffer will adjust the allocated space automatically when you insert or delete elements.
val newArrayBuff = new ArrayBuffer[Int]()
Adding Elements
Let’s now populate newArrayBuffer. To add an element to an ArrayBuffer you use the assignment operator += which appends the specified element to the end of an ArrayBuffer.
import scala.collection.mutable.ArrayBufferval newArrayBuff = new ArrayBuffer[Int]()newArrayBuff += 6newArrayBuff += 15newArrayBuff += 78newArrayBuff += 4newArrayBuff += 32newArrayBuff += 11// Driver CodenewArrayBuff.foreach(println)
Deleting Elements
There are multiple ways to delete an element from an ArrayBuffer. Let’s look at the ones which are most commonly used.
For all the examples below, we will be working with
newArrayBuff. Remember that our original ArrayBuffer contains the elements .
-= Assignment Operator
The same way we add an element using +=, we can remove a specific element using -=.
import scala.collection.mutable.ArrayBufferval newArrayBuff = new ArrayBuffer[Int]()newArrayBuff += 6newArrayBuff += 15newArrayBuff += 78newArrayBuff += 4newArrayBuff += 32newArrayBuff += 11newArrayBuff -= 78 //Remove the element with the value 78// Driver CodenewArrayBuff.foreach(println)
Our updated ArrayBuffer is now .
remove method
If we want to remove an element at a specific index, we can use the remove method.
import scala.collection.mutable.ArrayBufferval newArrayBuff = new ArrayBuffer[Int]()newArrayBuff += 6newArrayBuff += 15newArrayBuff += 78newArrayBuff += 4newArrayBuff += 32newArrayBuff += 11newArrayBuff -= 78newArrayBuff.remove(4) //Remove the element at the 4th index// Driver CodenewArrayBuff.foreach(println)
Our updated ArrayBuffer is now
clear method
If we want to remove all the elements from an ArrayBuffer, we can use the clear method.
import scala.collection.mutable.ArrayBufferval newArrayBuff = new ArrayBuffer[Int]()newArrayBuff += 6newArrayBuff += 15newArrayBuff += 78newArrayBuff += 4newArrayBuff += 32newArrayBuff += 11newArrayBuff -= 78newArrayBuff.remove(4)newArrayBuff.clear() //Remove all the elements from newArrayBuff// Driver CodenewArrayBuff.foreach(println)
In the code widget above, no output is displayed. This is because all the elements from newArrayBuff have been removed.
With this, our discussion on Arrays and ArrayBuffers comes to an end. In the next lesson, you will be challenged to create and populate an array of your own.