ArrayList declaration in java

Question

Is this formula is legal in java to declare ArrayList

List<Integer> list1 = new ArrayList<Integer>() {1,2,3,4,5};

Answer 1

Java 8 provides several alternatives, such as:

List<Integer> list1 = IntStream.of(1, 2, 3, 4, 5).boxed().collect(toList());
List<Integer> list1 = IntStream.rangeClosed(1, 5).boxed().collect(toList());

With Java 7 you need to use:

List<Integer> list1 = Arrays.asList(1, 2, 3, 4, 5); //can't add or remove
List<Integer> list1 = new ArrayList<> (Arrays.asList(1, 2, 3, 4, 5));

Answer 2

No you cant do use it like that Have a read of both this and this. These two pages would clear all your doubts regarding declaring arrayLists. Or if you just want the solution, List<Integer> list1= new ArrayList<Integer>(Arrays.asList(1,2,3,4,5));

Answer 3

No, But there are other ways to do that,

List<Integer> list1= new ArrayList<Integer>(Arrays.asList(1,2,3,4,5));

or you an use anonymous inner class

Answer 4

You can do it with that array initialization notation like this:

ArrayList<Integer> list1 = new ArrayList(Arrays.asList(new Integer[] {1, 2, 3, 4, 5 }));