I am calling the sorted method on a stream. And the java doc says:
"Sorted method returns a stream consisting of the elements of this stream, sorted according to natural order."
But when I run the code below:
List<String> list = new ArrayList<String>();
list.add("b");
list.add("a");
list.add("z");
list.add("p");
list.stream().sorted();
System.out.println(list);
I am getting output as
[b, a, z, p]
Why am I not getting the output of a natural sort?
Change this
list.stream().sorted();
System.out.println(list);
to something like
list.stream().sorted().forEachOrdered(System.out::println);
Your method is println the list (not the sorted stream). Alternatively (or additionally), you could shorten your initialization routine and re-collect the List like
List<String> list = new ArrayList<>(Arrays.asList("b","a","z","p"));
list = list.stream().sorted().collect(Collectors.toList());
System.out.println(list);
Which outputs (as you probably expected)
[a, b, p, z]
forEachOrdered, not forEach.
Arrays.asList to an ArrayList; the method Arrays.asList returns a List. In either case, the list is mutable and doesn’t need a stream detour like list = list.stream().sorted().collect(Collectors.toList()); a simple list.sort(null); will sort the list in-place.You should collect the result of the sorting and then assign it to your list.
List<String> list = new ArrayList<String>();
list.add("b");
list.add("a");
list.add("z");
list.add("p");
list = list.stream().sorted().collect(Collectors.toList());
System.out.println(list);
If you want to have your sorted list.
Let's change this
list.stream().sorted();
to
list.sort((e1, e2) -> e1.compareTo(e2));
Hope this help!
list.stream().sorted() and calling list.sort(…)? The custom comparator might be obsolete, still, this answer is correct.list.sort(null) or list.sort(Comparator.naturalOrder())…Comparator.naturalOrder() is to the point.Your stream has no terminal operator, and therefore is not processed. Terminal operators include but are not limited to: forEach, toArray, reduce, collect. Your code segment should be similar to
list.stream().sorted().forEachOrdered(System.out::println);
forEachOrdered, not forEach.
List” as there is no “current stream”. Naming things that wrong leads to exactly the confusion, the OP has shown.