Menu
For a data class , you can use the compiler-generated copy() method. Note that it will perform a shallow copy. To create a copy of a collection, use the toList() or toSet() methods, depending on the collection type you need. These methods always create a new copy of a collection; they also perform a shallow copy.
There is a way to make a deep copy of an object in Kotlin (and Java): serialize it to memory and then deserialize it back to a new object. This will only work if all the data contained in the object are either primitives or implement the Serializable interface.
This works fine.
val selectedSeries = series.toMutableList()
You can use
List -> toList()
Array -> toArray()
ArrayList -> toArray()
MutableList -> toMutableList()
Example:
val array = arrayListOf("1", "2", "3", "4")
val arrayCopy = array.toArray() // copy array to other array
Log.i("---> array " , array?.count().toString())
Log.i("---> arrayCopy " , arrayCopy?.count().toString())
array.removeAt(0) // remove first item in array
Log.i("---> array after remove" , array?.count().toString())
Log.i("---> arrayCopy after remove" , arrayCopy?.count().toString())
print log:
array: 4
arrayCopy: 4
array after remove: 3
arrayCopy after remove: 4
If your list is holding kotlin data class, you can do this
selectedSeries = ArrayList(series.map { it.copy() })
I can come up with two alternative ways:
1. val selectedSeries = mutableListOf<String>().apply { addAll(series) }
2. val selectedSeries = mutableListOf(*series.toTypedArray())
Update: with the new Type Inference engine(opt-in in Kotlin 1.3), We can omit the generic type parameter in 1st example and have this:
1. val selectedSeries = mutableListOf().apply { addAll(series) }
FYI.The way to opt-in new Inference is kotlinc -Xnew-inference ./SourceCode.kt for command line, or kotlin { experimental { newInference 'enable'} for Gradle. For more info about the new Type Inference, check this video: KotlinConf 2018 - New Type Inference and Related Language Features by Svetlana Isakova, especially 'inference for builders' at 30'
Just like in Java:
List:
val list = mutableListOf("a", "b", "c")
val list2 = ArrayList(list)
Map:
val map = mutableMapOf("a" to 1, "b" to 2, "c" to 3)
val map2 = HashMap(map)
Assuming you're targeting the JVM (or Android); I'm not sure it works for other targets, as it relies on the copy constructors of ArrayList and HashMap.
If you love us? You can donate to us via Paypal or buy me a coffee so we can maintain and grow! Thank you!
Donate Us With