What are the difference between Equality Operator and Referential Equality Operator

In Kotlin, == and === are used for equality comparisons, but they serve different purposes.

1. == (Equality Operator):

   • The == operator is used for structural equality, meaning it checks if the content or values of two objects are the same.
   • For primitive types (like numbers), == checks for value equality.
   • For non-primitive types (objects), == by default calls the equals method to compare the content of the objects.

   Example:

   val a: Int = 5
   val b: Int = 5
   println(a == b)  // true, because the values are the same

2. === (Referential Equality Operator):

   • The === operator is used for referential equality, meaning it checks if two references point to the exact same object in memory.
   • It is similar to the == operator in Java for object references.

   Example:

   val x: Int = 10
   val y: Int = 10
   val z: Int = x
   
   println(x === y)  // false, different memory locations
   println(x === z)  // true, both references point to the same object

3. Prints: true for integers (primitive types share the same memory)

val firstInput = 5
val secondInput = 5

println(firstInput === secondInput) // Prints: true for integers (primitive types share the same memory)

4. Prints: false (different objects with the same content)

val firstList = listOf(1, 2, 3)
val secondList = listOf(1, 2, 3)

println(firstList === secondList) // Prints: false (different objects with the same content)

In summary:

• Use == for checking if the content or values are the same.
• Use === for checking if two references point to the exact same object in memory.