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How to check if two HashSets are equal in Kotlin

How to check if two HashSets are equal in Kotlin.

Here's a step-by-step tutorial on how to check if two HashSets are equal in Kotlin:

Step 1: Create two HashSets​

First, create two HashSets that you want to compare for equality. For example:

val set1 = hashSetOf("apple", "banana", "orange")
val set2 = hashSetOf("apple", "banana", "orange")

Step 2: Use the equals() function​

In Kotlin, you can check if two HashSets are equal by using the equals() function. This function compares the elements of the HashSets and returns true if they are equal, and false otherwise. For example:

val areEqual = set1.equals(set2)

Step 3: Print the result​

To see the result of the comparison, you can use the println() function to print the value of the areEqual variable. For example:

println("Are the HashSets equal? $areEqual")

Step 4: Implement a custom equality check​

By default, the equals() function compares the elements of the HashSets using their content. If you want to use a custom equality check, you can create a custom implementation of the equals() function.

For example, let's say you have a custom data class called Person and you want to compare HashSets of Person objects based on their IDs. You can override the equals() function in the Person class to compare the IDs like this:

data class Person(val id: Int, val name: String) {
    override fun equals(other: Any?): Boolean {
        if (this === other) return true
        if (other == null || javaClass != other.javaClass) return false

        return id == (other as Person).id
    }

    override fun hashCode(): Int {
        return id
    }
}

Then, you can create two HashSets of Person objects and compare them using the equals() function:

val person1 = Person(1, "John")
val person2 = Person(2, "Jane")
val set1 = hashSetOf(person1, person2)
val set2 = hashSetOf(person1, person2)

val areEqual = set1.equals(set2)
println("Are the HashSets equal? $areEqual")

In this case, the equals() function will compare the Person objects based on their IDs, and the result will depend on whether the IDs are equal or not.

That's it! You now know how to check if two HashSets are equal in Kotlin.