Java 数组 output 格式化

Question

I know, we need to use fortmat() method while formatting the output. Here is my below code:

int arr[] = { 38, 27, 43, 3, 9, 82, 10 };
    Arrays.stream(arr).forEach(s -> System.out.format("%2d", s));
//output     382743 3 98210

If i use below code:

Arrays.stream(arr).forEach(s -> System.out.format("%3d", s));
//output  38 27 43  3  9 82 10

I want to print the output only with one space between the next value. something like 38 27 43 3 9 82 10

Answer 1

System.out.format() works with placeholders. So the %d stands for a 'decimalValue' that you give him afterwards. With the number you can specify the 'width' of the placeholder. So %3d will always have at least 3 width. Docs .

If you only want to output the value with one space between make something like:

Arrays.stream(arr).forEach(s -> System.out.format("%d ", s));

Then you will put the decimalValue (without specifying a width) and a " " (space) afterwards, foreach entry in the array.

Answer 2

If you want a space separator between elements of your int array it is possible use the StringJoiner class like below:

int arr[] = { 38, 27, 43, 3, 9, 82, 10 };
StringJoiner sj = new StringJoiner(" ");
for (int i : arr) { sj.add(String.valueOf(i)); }
String spaceSeparatedNumbers = sj.toString();
System.out.println(spaceSeparatedNumbers); //<-- 38 27 43 3 9 82 10