快速将String转换为Java中的int数组

Question

does anyone know a faster way to convert string to int array?

Java V7

The format given is " 4 343 234 -24 " and so on. Spaces between the numbers, amount of numbers is known beforhand just as is the range within the numbers are

long[] array = new long[length];            
for (int i = 0; i < length - 1; i++) {
    array[i] = Integer.parseInt(n.substring(0, n.indexOf(' ')));
    n = n.substring(n.substring(0, n.indexOf(' ')).length() + 1);
}
array[length - 1] = Integer.parseInt(n);

Answer 1

Using String.split() is by far the most efficient when you want to split by a single character (a space, in your case).

If you are aiming for maximal efficiency when splitting by spaces, then this would be a good solution:

List<Integer> res = new ArrayList<>();
Arrays.asList(kraft.split(" ")).forEach(s->res.add(Integer.parseInt(s)));
Integer[] result = res.toArray(new Integer[0]);

And this works for any number of numbers.

Answer 2

if You are using Java8 or higher version then you can get your expected output by writing this single line of code.

String str= "4 343 234 -24";

int[] intArr=Stream.of(str.split(" ")).mapToInt(Integer::parseInt).toArray();

System.out.println(Arrays.toString(intArr));

Answer 3

Splitting the input with the pattern \\\\s+ would handle one or more white-space characters, not only spaces, appearing between the numbers.

Stream.of(input.split("\\s+")).mapToInt(Integer::parseInt).toArray();

The mapToInt method returns an IntStream which provides the toArray method. This method returns an array containing the elements of the IntStream .