java - Function for changes a cell in a list

Question

I have a list of User objects with the values ??name and date, which at position 0 have the values ??Kate and 15:37. What a function should look like, which, when called, will change the values ??in this cell (at position 0) to Peter and 15:15 Here is my code:

class Test {
 private var list = mutableListOf<User>()
 private var user: User? = null

 private fun addItem() {
       user = User("Kate","15:37")
       list.add(0, user!!)
}
}

at a certain place in the code, I call the addItem method and I have a cell with the values Kate and 15:37. After that, I want to call a function that will change the values ??in this cell ...

Answer 1

Do you just want to change the item at position 0 in the list?

list[0] = User("Peter", "15:15")

If you want to replace the item with one that's a copy, but with certain changes:

list[0] = list[0].copy(name="Peter")

If you want to keep the same object at position 0, but change its state:

// note the use of var, so the properties are mutable
data class User(var name: String, var date: String)

// "get item 0, if it's not null, set these things on it",
// this is just a neat and concise way to do it
list[0]?.run {
    name = "Peter"
    date = "15:15"
}