Is it possible to assign an array
to an ArrayList
in Java?
ArrayList of arrays can be created just like any other objects using ArrayList constructor. In 2D arrays, it might happen that most of the part in the array is empty. For optimizing the space complexity, Arraylist of arrays can be used.
The clone() method of the ArrayList class is used to clone an ArrayList to another ArrayList in Java as it returns a shallow copy of its caller ArrayList.
You can use Arrays.asList()
:
Type[] anArray = ...
ArrayList<Type> aList = new ArrayList<Type>(Arrays.asList(anArray));
or alternatively, Collections.addAll()
:
ArrayList<Type> aList = new ArrayList<Type>();
Collections.addAll(theList, anArray);
Note that you aren't technically assigning an array to a List (well, you can't do that), but I think this is the end result you are looking for.
The Arrays
class contains an asList
method which you can use as follows:
String[] words = ...;
List<String> wordList = Arrays.asList(words);
If you are importing or you have an array (of type string) in your code and you have to convert it into arraylist (offcourse string) then use of collections is better. like this:
String array1[] = getIntent().getExtras().getStringArray("key1"); or
String array1[] = ...
then
List<String> allEds = new ArrayList<String>();
Collections.addAll(allEds, array1);
This is working
int[] ar = {10, 20, 20, 10, 10, 30, 50, 10, 20};
ArrayList<Integer> list = new ArrayList<>();
for(int i:ar){
list.add(new Integer(i));
}
System.out.println(list.toString());
// prints : [10, 20, 20, 10, 10, 30, 50, 10, 20]
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