Why I cannot split string with $ in Java

Question

I was just doodling on eclipse IDE and written following code.

String str = new String("A$B$C$D");
String arrStr[] = str.split("$");
for (int i = 0; i < arrStr.length; i++) {
    System.out.println("Val: "+arrStr[i]);
}

I was expecting output like: Val: A Val: B Val: C Val: D
But instead of this, I got output as

Val: A$B$C$D Why? I am thinking may be its internally treated as a special input or may be its like variable declaration rules.

possible duplicate of [Why does String.split need pipe delimiter to be escaped?](http://stackoverflow.com/questions/9808689/why-does-string-split-need-pipe-delimiter-to-be-escaped) — Raedwald, Jul 17 '15 at 11:41

score 11 · Accepted Answer · answered Jul 14 '15 at 08:57

11

The method String.split(String regex) takes a regular expression as parameter so $ means EOL.

If you want to split by the character $ you can use

String arrStr[] = str.split(Pattern.quote("$"));

answered Jul 14 '15 at 08:57

Uli

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A little overhead for escaping the dollar symbol ;) – VWeber Jul 14 '15 at 08:58
3

You don't have to think about how to escape any character => less error prone. – Uli Jul 14 '15 at 09:00
But split method will work if I use different characters like "_" or ",". – Avinash Mishra Jul 14 '15 at 09:00
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@Avinash: "_" and "," are no special regexp characters. They are treated as they are. Please read the javadoc for regular expressions: http://docs.oracle.com/javase/8/docs/api/java/util/regex/Pattern.html – Uli Jul 14 '15 at 09:11

VWeber · Answer 2 · 2015-07-14T10:57:48.373

8

You have to escape "$":

arrStr = str.split("\\$");

edited Jul 14 '15 at 10:57

answered Jul 14 '15 at 08:56

VWeber

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score 4 · Answer 3 · answered Jul 14 '15 at 08:58

You have used $ as regex for split. That character is already defined in regular expression for "The end of a line" (refer this). So you need to escape the character from actual regular expression and your splitting character should be $.

So use str.split("\\$") instead of str.split("$") in your code

score 3 · Answer 4 · answered Jul 14 '15 at 09:03

The split() method accepts a string that resembles a regular expression (see Javadoc). In regular expressions, the $ char is reserved (matching "the end of the line", see Javadoc). Therefore you have to escape it as Avinash wrote.

String arrStr[] = str.split("\\$");

The double-backslash is to escape the backslash itself.

score 1 · Answer 5 · answered Jul 14 '15 at 09:03

Its simple. The "$" character is reserved that means you need to escape it.

String str = new String("A$B$C$D");
String arrStr[] = str.split("\\$");
for (int i = 0; i < arrStr.length; i++) {
    System.out.println("Val: "+arrStr[i]);
}

That should work fine. So whenever something like this happens escape the character!

Why I cannot split string with $ in Java

5 Answers5