I thought that only affects whether or not you can expand or kotlinlang #getting-started

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Title

h

Hullaballoonatic

09/20/2018, 3:21 PM

I thought that only affects whether or not you can expand or contract the size of the list

r

Ruckus

09/20/2018, 6:24 PM

You're thinking Array vs List, not List vs MutableList

h

Hullaballoonatic

09/20/2018, 6:25 PM

well MutableList == ArrayList, whereas I honestly don't really know the functional difference between Array and List

r

Ruckus

09/20/2018, 6:27 PM

Array is a specific data structure in memory, whereas List is an interface. ArrayList is a List backed by an Array, but you can have Lists backed by other mechanisms, such as LinkedList.

h

Hullaballoonatic

09/20/2018, 6:28 PM

In java, i only ever used

List

as an type, but in kotlin i use it in the same way i'd use java arrays

am i misusing things?

kotlin list != java list, yeah?

r

Ruckus

09/20/2018, 6:30 PM

Good rule of thumb is always use a List unless you specifically need an Array (if you're not sure, you probably don't need an array). Note that ArrayList is a List, not an Array (it just uses an array internally).

Ultimately Kotlin Lists and Java Lists are the same (on the JVM of course), but they have a slightly different interface. Java assumes all Lists are mutable, whereas Kotlin does not, and instead distinguishes between List and MutableList. In Java, if you create an immutable list, it will just be a List with all the mutating functions throwing exceptions.

Basically (assuming you have an immutable list), in Java

list.add(...)

throws an exception, whereas in Kotlin

list.add(...)

doesn't exist.

h

Hullaballoonatic

09/20/2018, 6:35 PM

thank you!

r

Ruckus

09/20/2018, 6:35 PM

Sure thing

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