Array to Collection: Optimized code

Question

Is there a better way of achieving this?

public static List toList(String[] array) {

    List list = new ArrayList(array.length);

          


        

Answer 1

What do you mean by better way:

more readable:

List<String> list = new ArrayList<String>(Arrays.asList(array));

less memory consumption, and maybe faster (but definitely not thread safe):

public static List<String> toList(String[] array) {
    if (array==null) {
       return new ArrayList(0);
    } else {
       int size = array.length;
       List<String> list = new ArrayList(size);
       for(int i = 0; i < size; i++) {
          list.add(array[i]);
       }
       return list;
    }
}

Btw: here is a bug in your first example:

array.length will raise a null pointer exception if array is null, so the check if (array!=null) must be done first.

Answer 2

Yes, there is. You can use the Arrays class from the java.util.* package. Then it's actually just one line of code.

List<String> list = Arrays.asList(array);

Answer 3

What about :

List myList = new ArrayList(); 
String[] myStringArray = new String[] {"Java", "is", "Cool"}; 

Collections.addAll(myList, myStringArray); 

Answer 4

You can try something like this:

List<String> list = new ArrayList<String>(Arrays.asList(array));

public ArrayList(Collection c)

Constructs a list containing the elements of the specified collection, in the order they are returned by the collection's iterator. The ArrayList instance has an initial capacity of 110% the size of the specified collection.

Taken from here

Answer 5

Have you checked Arrays.asList(); see API

Answer 6

You can use:

list.addAll(Arrays.asList(array));