I have a List of ArrayList and would like to add predefined values to it using addall
List<ArrayList<String>> places;
But I'm not sure how to do so. Will it look something like the following:
places.addall(["a","b","c"],["aa","bb","cc"]....);
I tried that and it's not working.
I don't think you can use addAll in that way, since addAll expects a Collection as the parameter; in your case it should be a Collection<? extends List<String>>
So, you need to create a Collection with the array looking data that you have and then add it to your places Collection.
The closest that i can think of is to do something as below,
List<List<String>> places = new ArrayList<List<String>>();
String[] string1 = new String[]{"a", "b", "c"};
String[] string2 = new String[]{"aa", "bb", "cc"};
places.add(Arrays.asList(string1));
places.add(Arrays.asList(string2));
If you really want to use addAll then you'll have to do something like this,
List<List<String>> tempPlaces = new ArrayList<List<String>>();
String[] string1 = new String[]{"a", "b", "c"};
String[] string2 = new String[]{"aa", "bb", "cc"};
tempPlaces.add(Arrays.asList(string1));
tempPlaces.add(Arrays.asList(string2));
List<List<String>> places = new ArrayList<List<String>>();
places.addAll(tempPlaces);
Collection, and that Arrays.asList() returns a Collection.
For your case first you add values to the ArrayList ArrayList al = new ArrayList(); al.add("Hi"); al.add("hello"); al.add("String"); al.add("Test"); ArrayList al1 = new ArrayList(); al1.add("aa"); al1.add("bb"); al1.add("cc"); al1.add("dd"); Now you add these elements to your List
List> places;
places.add(al); places.add(al1);
