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What is the ArrayList.containsAll() method in Kotlin?

Siddharth Singh

Grokking Modern System Design Interview for Engineers & Managers

Ace your System Design Interview and take your career to the next level. Learn to handle the design of applications like Netflix, Quora, Facebook, Uber, and many more in a 45-min interview. Learn the RESHADED framework for architecting web-scale applications by determining requirements, constraints, and assumptions before diving into a step-by-step design process.

Overview

The kotlin.collections package is part of Kotlin’s standard library and contains all collection types, such as Map, List, Set, etc.

The package provides the ArrayList class, which is a mutable list and uses a dynamic, resizable array as the backing storage.

The containsAll() method

The ArrayList class contains the containsAll() method, which checks for the presence of all elements of the specified input collection in the array list.

Syntax

fun containsAll(elements: Collection<E>): Boolean

Parameters

The containsAll() method takes the collection of elements to search as input.

Return value

containsAll() returns true if all the elements of the input collection are present in the array list, and false otherwise.

Things to note

  • ArrayList follows the sequence of insertion of elements.

  • ArrayList is allowed to contain duplicate elements.

The illustration below shows the function of the containsAll() method.

Checking if all elements of a collection are present in the array list using the containsAll() method
fun main(args : Array<String>) {
val monthList = ArrayList<String>()
monthList.add("January")
monthList.add("February")
monthList.add("March")
monthList.add("April")
monthList.add("May")
println("Printing ArrayList elements--")
println(monthList)
val inputList = ArrayList<String>()
inputList.add("January")
inputList.add("February")
println("Printing Input collection elements--")
println(inputList)
val result = monthList.containsAll(inputList)
println("Is input list present in the array list? : ${result}")
}

Explanation

  • Line 2: We create an empty array list named monthList to store the strings.

  • Line 4 to 8: We use the add() method to add a few month names to the ArrayList object, such as "January", "February", "March", "April", and "May".

  • Line 12 to 14: We create a new array list inputList and add month names "January" and "February" to it.

  • Line 17: We call the containsAll() method and pass the inputList collection as the parameter. The containsAll() method returns true, as all elements of the input collection are present in the array list.

We use the println() function of the kotlin.io package to display the Arraylist elements and result of the containsAll() method.

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kotlin
communitycreator

Grokking Modern System Design Interview for Engineers & Managers

Ace your System Design Interview and take your career to the next level. Learn to handle the design of applications like Netflix, Quora, Facebook, Uber, and many more in a 45-min interview. Learn the RESHADED framework for architecting web-scale applications by determining requirements, constraints, and assumptions before diving into a step-by-step design process.

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