Sorting an ArrayList of numbers, in numerical order

Question

I have a String list of numbers (they can be an int list, just need to turn it into an array list to return), this numbers can be from a range, for example from 1 to 25.

I tried sorting them using Collections.sort(numbersList); but it sorts them in a weird way. For example this is the current sorting:

1
10
11
..
2
20
21
..

What I really want is for it to be sorted in a numerical order, for example:

1
2
3
..
10
11
..

Tried to sort them as an int[] with Arrays.sort(numbers); but it gives the same result.

Here is the code that I use to generate the numbers and turn them into an array list.

int[] range = IntStream.rangeClosed(1, 30).toArray();
Arrays.sort(range);
List<String> rangeList = new ArrayList<>();
for (int number : range) {
    rangeList.add(String.valueOf(number));
}

Answer 1

I feel like I've seen this before, but you can try the following in Java 8+ (where numbersList is the String[]):

Arrays.sort(numbersList, Comparator.comparing(Integer::valueOf));

Additionally, in your code, you have a problem in your initialization of range, because the parenthesis for Integer.parseInt is not closed, and the parameters are wrong. It should be replaced with the following:

int[] range = IntStream.rangeClosed(1, 30).toArray();

完成此操作后，您无需进行排序，因为IntStream.rangeClosed保证将按排序顺序提供IntStream中的所有元素。如果您想了解有关如何正确使用Integer.parseInt的更多信息，我强烈建议您查看Javadoc。