String#replaceAll() method not replacing for $ (dollar)

Question

I've tried built-in method String#replaceAll() to replace all "$" from my String content. But it's not working.

String ss = "HELLO_$_JAVA";
System.out.println(ss.indexOf("$"));
System.out.println(ss);
ss = ss.replaceAll("$", "");
System.out.println(ss);// 'HELLO__JAVA' is expected

OUTPUT:

6
HELLO_$_JAVA
HELLO_$_JAVA

Expected output:

6
HELLO_$_JAVA
HELLO__JAVA

EDIT: Although Java regular expressions and dollar sign covers the answer, but still my question may be helpful for someone who is facing same problem when using String#replaceAll(). And Difference between String replace() and replaceAll() also may be helpful.

Two possible solution of that question is

ss = ss.replace("$", "");

OR

ss = ss.replaceAll("\\$", "");

Why should `HELLO_$_JAVA` be the expected output? Where should the `_` come from? — Markus Weninger, Mar 07 '16 at 10:26
I find it very weird that the `"HELLO$JAVA"` string is being printed as `HELLO_$_JAVA` — Shark, Mar 07 '16 at 10:26
like hinted by the previous comments, your code does not match the output you've shown. That's not the way it works. — eis, Mar 07 '16 at 10:27

score 9 · Answer 1 · answered Mar 07 '16 at 10:26

The first parameter of the replaceAll method takes a regular expression, not a literal string, and $ has a special meaning in regular expressions.

You need to escape the $ by putting a backslash in front of it; and the backslash needs to be double because it has a special meaning in Java string literals.

ss = ss.replaceAll("\\$", "");

score 8 · Accepted Answer · answered Mar 07 '16 at 10:25

8

String.replaceAll is for regular expressions. '$' is a special character in regular expressions.

If you are not trying to use regular expressions, use String.replace, NOT String.replaceAll.

answered Mar 07 '16 at 10:25

khelwood

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Nabin · Answer 3 · 2016-03-07T10:31:50.497

-1

May be not the best way but a work around,

String parts[] = ss.split("\\$");

Then concat each of them

String output = "";
for(String each:parts){
    output=output+each;
}

Then you have your replaced string in output

edited Mar 07 '16 at 10:31

answered Mar 07 '16 at 10:26

Nabin

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why should op do this? – eis Mar 07 '16 at 10:28
@eis Just a work around. – Nabin Mar 07 '16 at 10:28
1

quite over the top, instead of using the regex for a split on `$` and concatination the array back he could have just replaced it with the correct regex in the first place. – SomeJavaGuy Mar 07 '16 at 10:29

String#replaceAll() method not replacing for $ (dollar)

3 Answers3