无法替换Java中的字符串

Question

If i have this String:

String line = "This, is Stack; Overflow.";

And want to split it into the following array of strings:

String[] array = ...

so the array contains this output:

["This",",","is","Stack",";","Overflow","."]

What regex expression should i put into the split() method ?

Answer 1

Just split your input according to the spaces or the boundaries which exists between a word character and a non-word character, vice-versa.

String s = "This, is Stack; Overflow.";
String parts[] = s.split("\\s|(?<=\\w)(?=\\W)");
System.out.println(Arrays.toString(parts));

\\s matches any kind of whitespace character, \\w matches a word character and \\W matches a non-word character.

• \\s matches a space character.
• (?<=\\\\w) Positive look-behind which asserts that the match must be preceded by a word character ( az , AZ , 0-9 , _ ).

• (?=\\\\W) Positive look-ahead which asserts that the match must be followed by a non-word character( any character other than the word character ). So this (?<=\\\\w)(?=\\\\W) regex matches only the boundaries not a character.

• Thus splitting the input according to the matches spaces and the boundaries will give you the desired output.

DEMO

OR

String s = "This, is Stack; Overflow.";
String parts[] = s.split("\\s|(?<=\\w)(?=\\W)|(?<=[^\\w\\s])(?=\\w)");
System.out.println(Arrays.toString(parts));

Output:

[This, ,, is, Stack, ;, Overflow, .]

Answer 2

You can do that with this pattern:

\\s+|(?<=\\S)(?=[^\\w\\s])|(?<=[^\\w\\s])\\b

it trims whitespaces and deals with consecutive special characters, example:

With ;This, is Stack; ;; Overflow. ;This, is Stack; ;; Overflow.

you obtain: [";", "This", ",", "is", "Stack", ";", ";", ";", "Overflow", "."]

But obviously, the more efficient way is to not use the split method but the find method with this pattern:

\\w+|[^\\w\\s]