what's the quickest way to convert an array to a LIST or Set?

Question

In Java, what's the qucikest way to convert an array to a List or a set?

String[] a = {"Test1", "test2"};

List<String> l = new ArrayList<String>();

Answer 1

Arrays.asList() works for your example of String[], but if your're converting a primitive array, such as int[] or double[], then this will produce a single item list of the array. A good solution is to use Google Guava's primitive helper classes, such as Ints:

int[] a = new int[]{1,2,3}; 
List<Integer> l = Ints.asList(a);

For a more detailed explanation, see this answer.

Answer 2

Use Google's Guava APIs, using collections is so much simpler.

String[] a = {"Test1", "test2"};
List<String> l = Lists.newArrayList(a);

Answer 3

Use the java.util.Arrays class.

List<String> list = Arrays.asList(new String[] {"a", "b"});

Note that the implementation of List you get by the above method isn't the same as java.util.ArrayList. If you want ArrayList implementation, use

List<String> list = new ArrayList<String>(Arrays.asList(new String[] {"a", "b"}));

Answer 4

List list = Arrays.asList(array);

Collections.addAll(list, array);

One of the first google link : http://javarevisited.blogspot.com/2011/06/converting-array-to-arraylist-in-java.html

Answer 5

http://docs.oracle.com/javase/7/docs/api/java/util/Arrays.html#asList(T...)

It would depend on your definition of "quickest", but in both cases this would be it.

Answer 6

To convert an array to a list use Arrays.asList:

String[] a = {"Test1", "test2"};
List<String> list = Arrays.asList(a);

To convert an array to a set:

Set<String> set = new HashSet<String>(Arrays.asList(a));

Answer 7

From the Arrays class (doc):

List<String> l = Arrays.asList(a);