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How to check if two HashMaps are equal in Kotlin

How to check if two HashMaps are equal in Kotlin.

Here is a detailed step-by-step tutorial on how to check if two HashMaps are equal in Kotlin.

Step 1: Create two HashMaps​

First, you need to create two HashMaps that you want to compare for equality. You can create them using the HashMap constructor or the hashMapOf function.

val map1 = HashMap<String, Int>()
val map2 = HashMap<String, Int>()

Step 2: Populate the HashMaps​

Next, populate the HashMaps with key-value pairs. You can use the put method to add elements to the HashMaps.

map1["key1"] = 1
map1["key2"] = 2

map2["key1"] = 1
map2["key2"] = 2

Step 3: Check the HashMap sizes​

Before comparing the HashMaps, it's a good practice to check if their sizes are equal. If the sizes are not equal, it means the HashMaps are not equal.

if (map1.size != map2.size) {
    println("HashMaps are not equal")
    return
}

Step 4: Compare the HashMaps​

To check if two HashMaps are equal, you can use the equals method. This method compares the contents of the HashMaps, including the keys and values.

if (map1 == map2) {
    println("HashMaps are equal")
} else {
    println("HashMaps are not equal")
}

Alternatively, you can also use the equals method explicitly to compare the HashMaps.

if (map1.equals(map2)) {
    println("HashMaps are equal")
} else {
    println("HashMaps are not equal")
}

Step 5: Check HashMap equality using custom logic​

If you want to compare the HashMaps using custom logic, such as ignoring the order of elements or comparing only specific keys, you can iterate over the HashMaps and compare the key-value pairs.

if (map1.size != map2.size) {
    println("HashMaps are not equal")
    return
}

for ((key, value) in map1) {
    if (map2[key] != value) {
        println("HashMaps are not equal")
        return
    }
}

println("HashMaps are equal")

This approach allows you to define your own rules for comparing the HashMaps.

That's it! You have learned how to check if two HashMaps are equal in Kotlin. You can choose the method that best suits your requirements and use it to compare HashMaps in your projects.