Moving data from a HashSet to ArrayList in Java

问题

I have the following Set in Java:

Set< Set<String> > SetTemp = new HashSet< Set<String> >();

and I want to move its data to an ArrayList:

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

Is it possible to do that ?

回答1:

You simply need to loop:

Set<Set<String>> setTemp = new HashSet<Set<String>> ();
List<List<String>> list = new ArrayList<List<String>> ();
for (Set<String> subset : setTemp) {
    list.add(new ArrayList<String> (subset));
}

Note: you should start variable names in small caps to follow Java conventions.

回答2:

Moving Data HashSet to ArrayList

Set<String> userAllSet = new HashSet<String>(usrAllTemp);
List<String> usrAll = new ArrayList<String>(userAllSet);

Here usrAllTemp is an ArrayList, which has some values. Same Way usrAll(ArrayList) getting values from userAllSet(HashSet).

回答3:

You can use addAll():

Set<String> gamesInstalledTemp = new HashSet< Set<String> >();
List<String> gamesInstalled = new ArrayList<>();
gamesInstalled.addAll(gamesInstalledTemp);

回答4:

You can use the Stream and collector to do this, I hope it is the easiest way

listname = setName.stream().collect(Collectors.toList());

来源：https://stackoverflow.com/questions/13632135/moving-data-from-a-hashset-to-arraylist-in-java