Scala Check if List Contains Duplicates

1. Introduction

In Scala, checking if a list contains duplicates is a common requirement, especially when ensuring data uniqueness is crucial. There are several ways to check for duplicates in a list, each with its own advantages. This blog post will demonstrate how to identify if a list in Scala contains duplicate elements.

2. Program Steps

1. Create a list that may contain duplicates.

2. Apply different methods to check for duplicates, including using a Set and custom logic.

3. Print the results to verify whether duplicates are present.

4. Execute the code to test each method.

3. Code Program

object ListDuplicatesCheckDemo extends App {
  val numbers = List(1, 2, 3, 2, 5)

  // Method 1: Using toSet and comparing lengths
  val hasDuplicates1 = numbers.toSet.size != numbers.size
  println(s"Has duplicates (using toSet)? $hasDuplicates1")

  // Method 2: Using groupBy and finding groups with more than one element
  val hasDuplicates2 = numbers.groupBy(identity).values.exists(_.size > 1)
  println(s"Has duplicates (using groupBy)? $hasDuplicates2")

  // Method 3: Using custom logic with foldLeft
  val hasDuplicates3 = numbers.foldLeft((false, Set[Int]())) {
    case ((result, seen), item) =>
      if (seen.contains(item)) (true, seen)
      else (result, seen + item)
  }._1
  println(s"Has duplicates (using custom logic)? $hasDuplicates3")
}

Output:

Has duplicates (using toSet)? true
Has duplicates (using groupBy)? true
Has duplicates (using custom logic)? true

Explanation:

1. The first method converts the list to a Set (which removes duplicates) and compares its size to the original list's size. If the sizes are different, it means there were duplicates.

2. The second method uses groupBy to group identical elements and then checks if any group has more than one element.

3. The third method involves a foldLeft operation that keeps track of seen elements and checks for duplicates as it iterates through the list.

4. In all cases, the output is true, indicating that the list numbers contains duplicates.


Related Scala Source Code Examples:

Scala program to print hello world Scala program to find the factorial of a number Scala program to check if a number is prime Scala program to find the Fibonacci series Scala program to reverse a string Scala program to count vowels in a string Scala program to implement bubble sort Scala program to find the largest element in an array Scala program to perform matrix multiplication Scala program to add two number Scala program to find prime numbers Scala program to check palindrome Scala program to find the maximum and minimum of an array Scala program to calculate the area of a circle Scala program to find the GCD of two numbers Scala program to check if a string is a palindrome Scala program to find the sum of digits of a number Scala program to count the number of words in a sentence Scala program to remove duplicates from a list Scala program to find the power of a number using recursion Scala program to convert Celsius to Fahrenheit Scala program to calculate compound interest Scala program to find the common elements in two arrays Scala program to check if two strings are anagrams Scala program to replace all occurrences of a substring Scala program to find the longest substring without repeating characters Scala program to split a string by a delimiter Scala program to find the sum and average of elements in an array Scala program to reverse an array Scala program to check if an array contains a specific value Scala program to merge two arrays Scala program to remove duplicates from an array Scala program to find the intersection of two arrays Scala program to find the rotation point in a rotated sorted array Scala program to find the power of a number Scala program to find all divisors of a number Scala program to reverse a list Scala program to concatenate two lists Scala program to find the last element in a list Scala program to remove duplicates from a list Scala program to sort a list of numbers Scala program to find the intersection of two lists Scala program to implement tail recursion Scala program to use Option, Some, and None for null safety Scala - custom flatMap or map function Scala program to calculate leap years Scala - Data Types Example Scala - Access Modifiers Example Scala - Arithmetic Operators Example Scala - Relational Operators Example Scala - Logical Operators Example Scala - Bitwise Operators Example Scala - IF ELSE Statements Example Scala - Loop Statements Example Scala - Functions Example Scala - Closures Example Scala - String Functions with Examples Scala - Array Functions with Examples Scala List Methods with Examples Scala Set Methods with Examples Scala Map Methods with Examples Scala - Tuples Example Scala - Exception Handling Example Scala Iterate Over an Array Scala Iterate Over List (Different Ways) Scala Iterate Over Map (Different Ways) Scala Iterate List With Index Scala Iterate Over List of Objects (Different Ways) Scala Iterate Over String Scala Convert List to Map Scala Convert String to Int Scala Convert String to Boolean Scala Convert String to Timestamp Scala Convert String to JSON Scala Convert String to Long Scala Convert Date to Epoch Scala Convert Map to JSON Scala Check if the List Contains an Element Scala Check if List Is Null or Empty Scala Check if List Contains Duplicates Scala Check if String Is Null or Empty Scala Check if Option Is None Scala Check Option Has Value Stack Implementation in Scala Queue Implementation in Scala Priority Queue Implementation in Scala Linked List Implementation in Scala Doubly Linked List Implementation in Scala Circular Linked List Implementation in Scala Binary Tree Implementation in Scala Bubble Sort Algorithm in Scala Selection Sort Algorithm in Scala Insertion Sort Algorithm in Scala Merge Sort Algorithm in Scala Quick Sort Algorithm in Scala Heap Sort Algorithm in Scala Shell Sort Algorithm in Scala Linear Search Algorithm in Scala Binary Search Algorithm in Scala

Comments

Post a Comment