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How to check if a HashSet contains a specific element in Kotlin

How to check if a HashSet contains a specific element in Kotlin.

Here is a detailed step-by-step tutorial on how to check if a HashSet contains a specific element in Kotlin.

Step 1: Create a HashSet​

To begin, you need to create a HashSet in Kotlin. A HashSet is a collection that does not allow duplicate elements. You can create a HashSet using the HashSet constructor or the hashSetOf function.

val mySet = HashSet<String>()

Step 2: Add elements to the HashSet​

Next, you need to add some elements to the HashSet. You can use the add method to add elements one by one, or you can use the addAll method to add a collection of elements.

mySet.add("Apple")
mySet.add("Banana")
mySet.add("Orange")

Step 3: Check if the HashSet contains a specific element​

To check if the HashSet contains a specific element, you can use the contains method. This method returns true if the element is found in the HashSet, and false otherwise.

val element = "Apple"
val containsElement = mySet.contains(element)
println("HashSet contains $element: $containsElement")

In the above example, we check if the HashSet mySet contains the element "Apple". The contains method returns true because "Apple" is present in the HashSet.

Step 4: Handle the result​

Once you have checked if the HashSet contains the element, you can handle the result accordingly. For example, you can use an if-else statement to perform different actions based on whether the element is found or not.

if (containsElement) {
    println("The HashSet contains $element")
} else {
    println("The HashSet does not contain $element")
}

This will output "The HashSet contains Apple" since "Apple" is present in the HashSet.

Step 5: Check if the HashSet is empty​

Before checking if a HashSet contains a specific element, it is often useful to check if the HashSet is empty. You can use the isEmpty method to determine if the HashSet does not contain any elements.

val isEmpty = mySet.isEmpty()
println("Is the HashSet empty? $isEmpty")

Step 6: Remove an element from the HashSet​

If you want to remove an element from the HashSet, you can use the remove method. This method removes the specified element from the HashSet if it exists.

val removed = mySet.remove("Apple")
println("Element removed: $removed")

In the above example, we remove the element "Apple" from the HashSet. The remove method returns true because "Apple" was present in the HashSet and it is successfully removed.

Step 7: Clear the HashSet​

If you want to remove all elements from the HashSet, you can use the clear method. This method clears the HashSet and makes it empty.

mySet.clear()
println("HashSet cleared")

Step 8: Use the extension function 'in'​

In Kotlin, you can also use the in operator as an extension function to check if a HashSet contains a specific element. This operator returns true if the element is found in the HashSet, and false otherwise.

val containsElement = element in mySet
println("HashSet contains $element: $containsElement")

This is equivalent to using the contains method.

That's it! You have learned how to check if a HashSet contains a specific element in Kotlin. You can now use these techniques to check for the presence of elements in your HashSet.