How to merge several List when initialization?

Question

How to merge several lists into one when define a new list?

Maybe I can override Collection.addAll()? But it just join two lists. And I've read Combine multiple Collections already.

e.g. I want to union the follow four list.

 private final static List<String> aList
    = new ArrayList<>(Arrays.asList(
            "aa",
            "aaa"
    ));

private final static List<String> bList
    = new ArrayList<>(Arrays.asList(
            "bb",
            "bbb"
    ));

private final static List<String> cList
    = new ArrayList<>(Arrays.asList(
            "cc",
            "ccc"
    ));

private final static List<String> dLsit
    = new ArrayList<>(Arrays.asList(
            "dd",
            "ddd
    ));

you can make a method which you pass x-amount of lists and the method calls the addAll() for all every list — XtremeBaumer, Nov 22 '16 at 09:50

score 0 · Answer 1 · answered Nov 22 '16 at 09:53

possible answer looks like this:

 public List mergeLists(List l1,List l2,List l3,List l4){
        List initialList=new ArrayList<>();
        initialList.addAll(l1);
        initialList.addAll(l2);
        initialList.addAll(l3);
        initialList.addAll(l4);
        return initialList;
    }

there is surely a better way to do so

How to merge several List when initialization?

1 Answers1