问题
I have a string which contains a contiguous chunk of digits and then a contiguous chunk of characters. I need to split them into two parts (one integer part, and one string).
I tried using String.split("\\D", 1)
, but it is eating up first character.
I checked all the String API and didn't find a suitable method.
Is there any method for doing this thing?
回答1:
Use lookarounds: str.split("(?<=\\d)(?=\\D)")
String[] parts = "123XYZ".split("(?<=\\d)(?=\\D)");
System.out.println(parts[0] + "-" + parts[1]);
// prints "123-XYZ"
\d
is the character class for digits; \D
is its negation. So this zero-matching assertion matches the position where the preceding character is a digit (?<=\d)
, and the following character is a non-digit (?=\D)
.
References
- regular-expressions.info/Lookarounds and Character Class
Related questions
- Java split is eating my characters.
- Is there a way to split strings with String.split() and include the delimiters?
Alternate solution using limited split
The following also works:
String[] parts = "123XYZ".split("(?=\\D)", 2);
System.out.println(parts[0] + "-" + parts[1]);
This splits just before we see a non-digit. This is much closer to your original solution, except that since it doesn't actually match the non-digit character, it doesn't "eat it up". Also, it uses limit
of 2
, which is really what you want here.
API links
- String.split(String regex, int limit)
- If the limit
n
is greater than zero then the pattern will be applied at mostn - 1
times, the array's length will be no greater thann
, and the array's last entry will contain all input beyond the last matched delimiter.
- If the limit
回答2:
There's always an old-fashioned way:
private String[] split(String in) {
int indexOfFirstChar = 0;
for (char c : in.toCharArray()) {
if (Character.isDigit(c)) {
indexOfFirstChar++;
} else {
break;
}
}
return new String[]{in.substring(0,indexOfFirstChar), in.substring(indexOfFirstChar)};
}
(hope it works with digit-only or char-only Strings too - can't test it here - if not, take it as a general idea)
来源:https://stackoverflow.com/questions/2995606/need-to-split-a-string-into-two-parts-in-java