What are the differences between object comparison methods in Kotlin and Java, and how do they work?

In Kotlin and Java, object comparison methods differ in name and behavior:

• In Java:

  • == compares references (i.e., checks if two variables point to the same object).
  • equals() is a method for checking logical equality of objects. By default, it is implemented in the Object class as reference comparison but is usually overridden to compare contents.

• In Kotlin:

  • == is an operator that calls the equals() method under the hood, meaning it checks for logical equality.
  • === is an operator for reference comparison, similar to == in Java.

Example:

val a = "test"
val b = String("test".toCharArray())

println(a == b)  // true, content comparison via equals()
println(a === b) // false, different objects in memory

Thus, in Kotlin, == is more convenient for comparing values, while === is used for checking object identity. In Java, for logical comparison, you need to explicitly call equals(), and == is used for reference checks.