The integer passed to the constructor represents its initial capacity, i.e., the number of elements it can hold before it needs to resize its internal array (and has nothing to do with the initial number of elements in the list). To initialize an list with 60 zeros you do: List<Integer> list = new ArrayList<Integer>(Collections.nCopies(60, 0)); … Read more
Native Java 8 (one line) With Java 8, int[] can be converted to Integer[] easily: int[] data = {1,2,3,4,5,6,7,8,9,10}; // To boxed array Integer[] what = Arrays.stream( data ).boxed().toArray( Integer[]::new ); Integer[] ever = IntStream.of( data ).boxed().toArray( Integer[]::new ); // To boxed list List<Integer> you = Arrays.stream( data ).boxed().collect( Collectors.toList() ); List<Integer> like = IntStream.of( … Read more
docs = docs.OrderBy(d => docsIds.IndexOf(d.Id)).ToList();
Use the Counter.most_common() method, it’ll sort the items for you: >>> from collections import Counter >>> x = Counter({‘a’:5, ‘b’:3, ‘c’:7}) >>> x.most_common() [(‘c’, 7), (‘a’, 5), (‘b’, 3)] It’ll do so in the most efficient manner possible; if you ask for a Top N instead of all values, a heapq is used instead of … Read more
There are functions in the Kotlin stdlib for average, count, distinct,filtering, finding, grouping, joining, mapping, min, max, partitioning, slicing, sorting, summing, to/from arrays, to/from lists, to/from maps, union, co-iteration, all the functional paradigms, and more. So you can use those to create little 1-liners and there is no need to use the more complicated syntax … Read more
If you’re using .NET 3.5 or .NET 4, it’s easy to create the dictionary using LINQ: Dictionary<string, ArrayList> result = target.GetComponents() .ToDictionary(x => x.Key, x => x.Value); There’s no such thing as an IEnumerable<T1, T2> but a KeyValuePair<TKey, TValue> is fine.
List<String> list = new ArrayList<String>(listOfTopicAuthors);
You can use Collections.list() to convert an Enumeration to a List in one line: List<T> list = Collections.list(enumeration); There’s no similar method to get a Set, however you can still do it one line: Set<T> set = new HashSet<T>(Collections.list(enumeration));
Java always calls the method that best suits your argument. Auto boxing and implicit upcasting is only performed if there’s no method which can be called without casting / auto boxing. The List interface specifies two remove methods (please note the naming of the arguments): remove(Object o) remove(int index) That means that list.remove(1) removes the … Read more
Check out Lists.partition(java.util.List, int) from Google Guava: Returns consecutive sublists of a list, each of the same size (the final list may be smaller). For example, partitioning a list containing [a, b, c, d, e] with a partition size of 3 yields [[a, b, c], [d, e]] — an outer list containing two inner lists … Read more