仅删除Java字符串中的X个空格

Question

So I'm parsing files of the following form (A and B not included in format) for "Item #", adding them to a list, given .'s are spaces for clarity:

Someword: a list of words of any length      (A)
....Item 1                                   (B)
....Item 2
.Item 3

Where section (A) is always of that form, and section B is always indented with either a tab (4 spaces) or a single space. My result is {Item 1,Item 2,Item 3}. Up until now, I've just used a regex to match the (A) section, then added the following lines with .trim() called on them.

My question is, how would I go about parsing through something that looks like this:

Someword: a list of words of any length 
........Item 1

Such that the second line has 8 spaces. So I want to ignore the first 4 (or potentially 1) spaces, and capture everything else, resulting in {....Item 1}, if x's are spaces in this case.

Answer 1

You can use one regex and get all items with on single pass:

Code

String str = "Someword: a list of words of any length\r\n" +
             "    Item 1\r\n" + // 4 spaces at the beginning
             "    Item 2\r\n" + // 4 spaces at the beginning
             " Item 3\r\n" + // 1 space at the beginning
             "        Item 4\r\n"; // 8 spaces at the beginning

Pattern p = Pattern.compile("(?m)^\\s+(Item\\s+\\d+)$");

Matcher m = p.matcher(str);
while(m.find()) {
    System.out.println(m.group(1));
}

Output

Item 1
Item 2
Item 3
Item 4

Description