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How to create and elements to a HashSet in Kotlin

How to create and elements to a HashSet in Kotlin.

Here's a step-by-step tutorial on how to create and add elements to a HashSet in Kotlin:

Step 1: Create a HashSet​

To create a HashSet in Kotlin, you can use the HashSet class. First, import the java.util.HashSet package. Then, declare a variable of type HashSet and initialize it with an empty HashSet:

import java.util.HashSet

val hashSet = HashSet<String>()

In this example, we are creating a HashSet to store strings. You can replace String with any other data type you want to store.

Step 2: Add Elements to the HashSet​

To add elements to the HashSet, you can use the add() method. Simply call the add() method on the HashSet variable and pass the element you want to add as an argument:

hashSet.add("Element 1")
hashSet.add("Element 2")

In this example, we are adding two elements ("Element 1" and "Element 2") to the HashSet.

Step 3: Check if an Element is Added​

To check if an element is successfully added to the HashSet, you can use the contains() method. Simply call the contains() method on the HashSet variable and pass the element you want to check as an argument. The method will return true if the element is present in the HashSet, and false otherwise:

val isAdded = hashSet.contains("Element 1")
println("Is Element 1 added to the HashSet? $isAdded")

This example checks if "Element 1" is present in the HashSet and prints the result.

Step 4: Add Multiple Elements at Once​

You can also add multiple elements to the HashSet at once using the addAll() method. This method takes another collection as an argument and adds all its elements to the HashSet:

val elementsToAdd = listOf("Element 3", "Element 4", "Element 5")
hashSet.addAll(elementsToAdd)

In this example, we have a list of elements elementsToAdd, and we add all these elements to the HashSet using the addAll() method.

Step 5: Iterate over the HashSet​

To iterate over the elements in the HashSet, you can use a for loop. Kotlin provides a convenient forEach function that can be used to iterate over a collection:

hashSet.forEach { element ->
    println(element)
}

This example iterates over each element in the HashSet and prints it.

Step 6: Remove Elements from the HashSet​

To remove elements from the HashSet, you can use the remove() method. Simply call the remove() method on the HashSet variable and pass the element you want to remove as an argument:

hashSet.remove("Element 1")

In this example, we are removing "Element 1" from the HashSet.

That's it! You have now learned how to create a HashSet in Kotlin, add elements to it, check if an element is added, add multiple elements at once, iterate over the HashSet, and remove elements from it.