java String replace method works but throwing error with replaceAll

Question

I have a string andn I want to replace { to \{ ... When I use replace method then it works but when I use replaceAll then it is giving error like Illegal repetition What is the reason?

String s = "One{ two } three {{{ four}";
System.out.println(s.replace("{", "\\{"));
System.out.println(s.replaceAll("{", "\\{"));

Expected output is - One\{ two } three \{\{\{ four}

replaceAll's first parameter must be regex, it's not treated as string or char. — px5x2
– px5x2, Commented Aug 27, 2015 at 8:11

Jordi Castilla · Accepted Answer · 2015-08-27 08:16:15Z

7

As explained String::replaceAll expects regex and Strinng::replace expects charSequence. So you must escape both \ and { in order to match as you expect.

String s = "One{ two } three {{{ four}";

System.out.println(s);
System.out.println(s.replace("{", "\\{"));
System.out.println(s.replaceAll("\\{", "\\\\{"));

Output:

One{ two } three {{{ four}
One\{ two } three \{\{\{ four}
One\{ two } three \{\{\{ four}

answered Aug 27, 2015 at 8:16

Jordi Castilla

27.1k8 gold badges73 silver badges113 bronze badges

Sign up to request clarification or add additional context in comments.

Comments

Rahul Yadav · Accepted Answer · 2015-08-27 08:11:39Z

2

String replaceAll expects regex whereas replace expects charSequence. Hence modifying the code

System.out.println(s.replaceAll("\\{", "\\{"));

Should work.

answered Aug 27, 2015 at 8:11

Rahul Yadav

1,5138 silver badges11 bronze badges

1 Comment

Rahul Yadav Over a year ago

@JordiCastilla the post has been modified after I answered the question. If we need the output after modification it would lokk like as follows: System.out.println(s.replaceAll("\\{", "\\\\{"));

Collectives™ on Stack Overflow

java String replace method works but throwing error with replaceAll

2 Answers 2

Comments

1 Comment

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

Comments

1 Comment

Your Answer

Sign up or log in

Post as a guest

Related