MainActivity.kt

        val user1 = User("john", 12345)
        val user2 = User("john", 123451)
        val user3 = User("john", 12345)

        println("==")
        println(user1==user2)
        println(user1==user3)

        println(" euquals")
        println(user1.equals(user2))
        println(user1.equals(user3))

        println("toString")
        println(user1.toString())

        println("hashCode")
        println(user1.hashCode())


class User(val name:String, val code:Int){


        override fun equals(other: Any?): Boolean {
           if(other == null || other !is User)
               return false
           return name == other.name && code==other.code
        }

        override fun hashCode(): Int =
            name.hashCode() * 31+code

        override fun toString(): String {
            return "Client(name=$name, code=$code"
        }
    }