使用正则表达式在正好一个空格处分割字符串

Question

I am trying to split a string using spaces but only if there is one space.

For example I have the following.

String s = "THIS IS A  TEST";

I want to take the result "THIS", "IS", "A TEST". How to form the regex to do the job?

Answer 1

Use lookarounds:

(?<!\s)(\s)(?!\s)

This regex matches space that's not followed and not preceded by a space.

In Java, it'll look:

"THIS IS A  TEST".split("(?<!\\s)(\\s)(?!\\s)");

Explanation:

• The regex (?<!a)b matches "b" that's not preceded by an "a"
• The regex b(?!a) matches "b" that's not followed by an "a"

Further reading:

• Lookarounds
• String#split

Answer 2

Since the argument to split() is a regular expression, you can look for one or more spaces (" +") instead of just one space (" ").

String[] array = s.split(" +");

You can also add and argument to limit the number of slips you want to split the string into.

String[] array = s.split(" +", N );

Where N is the number of splits you want to divide the string into.

Answer 3

您可以尝试使用单词边界的此正则表达式。

string.split("\\b\\s\\b");