Empty set literal?
No, there’s no literal syntax for the empty set. You have to write set().
set
Convert Set to List without creating new List
You can use the List.addAll() method. It accepts a Collection as an argument, and your set is a Collection. List<String> mainList = new ArrayList<String>(); mainList.addAll(set); EDIT: as respond to the edit of the question. It is easy to see that if you want to have a Map with Lists as values, in order to have … Read more
How to retrieve an element from a set without removing it?
Two options that don’t require copying the whole set: for e in s: break # e is now an element from s Or… e = next(iter(s)) But in general, sets don’t support indexing or slicing.
Does Python have an ordered set?
The answer is no, but you can use collections.OrderedDict from the Python standard library with just keys (and values as None) for the same purpose. Update: As of Python 3.7 (and CPython 3.6), standard dict is guaranteed to preserve order and is more performant than OrderedDict. (For backward compatibility and especially readability, however, you may … Read more
How to convert an Array to a Set in Java
Like this: Set<T> mySet = new HashSet<>(Arrays.asList(someArray)); In Java 9+, if unmodifiable set is ok: Set<T> mySet = Set.of(someArray); In Java 10+, the generic type parameter can be inferred from the arrays component type: var mySet = Set.of(someArray); Be careful Set.of throws IllegalArgumentException – if there are any duplicate elements in someArray. See more details: … Read more
Get difference between two lists
To get elements which are in temp1 but not in temp2 : In [5]: list(set(temp1) – set(temp2)) Out[5]: [‘Four’, ‘Three’] Beware that it is asymmetric : In [5]: set([1, 2]) – set([2, 3]) Out[5]: set([1]) where you might expect/want it to equal set([1, 3]). If you do want set([1, 3]) as your answer, you can use set([1, … Read more