Question

In Java, i want to get subList from a list. i cannot use subList of java as i want sub list based on some valus in list.

I have List of DTO objects. DTO is like

MyClass myClass;
int hit;

And MyClass is like

String webName;
...

I want to get sublists which has same webName (i need to add total hits of webName and remove dupicate DTO objects which has same webName )

Answer 1

Judging from your question, what you have now is

List<MyDTO> dtos;

and you want to get to

List<List<MyDTO>> sublists;

So just iterate over your dto’s, find the correct entry in a map, and add the hits to the container. The map will make sure you have only one entry per webname.

Map<String, List<MyDTO>> hitmap = new HashMap<String, List<MyDTO>>();

for (MyDTO dto: dtos){
  String webname = dto.getMyClass().getWebName();
  List<MyDTO> list = hitmap.get(webname);
  if (list==null){
    list = new ArrayList<MyDTO>();
    hitmap.put(webname, list);
  }
  list.add(dto);
}

Then, if you really just want the bunch of sublists, just get it from the values

List<List<MyDTO>> sublists = new ArrayList<List<MyDTO>>(hitmap.values());