Java - String replace exact word

Question

String x = "axe pickaxe";
x = x.replace("axe", "sword");
System.out.print(x);

By this code, I am trying to replace the exact word axe with sword. However, if I run this, it prints sword picksword while I would like to print sword pickaxe only, as pickaxe is a different word from axe although it contains it. How can I fix this? Thanks

That wouldn't solve this if axe is in a parenthesis for example or is followed by a comma. — Oti Na Nai
– Oti Na Nai, Commented May 12, 2015 at 6:57
Rather than java this problem should have regular expression tag — Nitin Dandriyal
– Nitin Dandriyal, Commented May 12, 2015 at 7:05
@OtiNaNai Why not? "(axe)" or "axe," would still differ from "kaxe" so yes it would — Suspended
– Suspended, Commented May 12, 2015 at 7:07

hiergiltdiestfu · Accepted Answer · 2015-05-12 06:58:22Z

60

Use a regex with word boundaries \b:

String s = "axe pickaxe";
System.out.println(s.replaceAll("\\baxe\\b", "sword"));

The backslash from the boundary symbol must be escaped, hence the double-backslashes.

answered May 12, 2015 at 6:58

hiergiltdiestfu

2,3572 gold badges25 silver badges36 bronze badges

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

1 Comment

Devin Ersoy Over a year ago

Is there a way to avoid replacing axe if the string contains specific characters such as '!' beforehand? For example, if the string is "!axe", then axe shouldn't be replaced (which it currently does), but it should be replaced with sword if the string is "axe!".

SubOptimal · Accepted Answer · 2017-02-20 07:12:40Z

19

Include the word boundary before and after the word you want to replace.

String x = "axe pickaxe axe";
x = x.replaceAll("\\baxe\\b", "sword");
System.out.print(x);

edit output

sword pickaxe sword

edited Feb 20, 2017 at 7:12

answered May 12, 2015 at 6:58

SubOptimal

23.1k3 gold badges57 silver badges70 bronze badges

Comments

Maroun · Accepted Answer · 2015-05-12 07:14:24Z

14

Some other answers suggest you to use \\b word boundaries to match an exact word. But \\bfoo\\b would match the substring foo in .foo.. If you don't want this type of behavior then you may consider using lookaround based regex.

System.out.println(string.replaceAll("(?<!\\S)axe(?!\\S)", "sword"));

Explanation:

(?<!\\S) Negative lookbehind which asserts that the match won't be preceded by a non-space character. i.e. the match must be preceded by start of the line boundary or a space.
(?!\\S) Negative lookahead which asserts that the match won't be followed by a non-space character, i.e. the match must be followed by end of the line boundary or space. We can't use (?<=^|\\s)axe(?=\\s|$) since Java doesn't support variable length lookbehind assertions.

DEMO

edited May 12, 2015 at 7:14

Maroun

96.3k30 gold badges195 silver badges249 bronze badges

answered May 12, 2015 at 7:03

Avinash Raj

175k32 gold badges247 silver badges289 bronze badges

5 Comments

Bathsheba Over a year ago

You might attract upvoting if you explained (?<!\\S)

hiergiltdiestfu Over a year ago

Nah, additional explanations don't appear to attract upvotes ;-P But back on topic: your solution precludes matching the end of a sentence, doesn't it? Then again, we don't really know about the general structure of OP's data set.

hiergiltdiestfu Over a year ago

Sure. String s = "axe. pickaxe"; System.out.println(s.replaceAll("(?<!\\S)axe(?!\\S)", "sword")); - output: "axe. pickaxe" (Oracle JDK 1.7.0-51)

Avinash Raj Over a year ago

@hiergiltdiestfu please read my solution again. I think op means the complete word as the one which don't have any character other than the original string. In your example, it has axe., so it fails. I though op means the complete word as the one which don't have any char preceding or following other than space.

hiergiltdiestfu Over a year ago

You made an assumption about the data set and some more details of the OP's intentions - that's OK. However, the OP's comments point elsewhere (see his 2nd comment on his q). Anyways, +1 for the fancy advanced lookaround stuff :)

Veselin Davidov · Accepted Answer · 2015-05-12 06:59:52Z

3

System.out.println("axe pickaxe".replaceAll("\\baxe\\b", "sword"));

You need to use replaceAll instead of replace - because it can work with regular expressions. Then use the meta character \b which is for word boundary. In order to use it you need to escape the \ as double \ so the reges become \\baxe\\b

answered May 12, 2015 at 6:59

Veselin Davidov

7,0911 gold badge17 silver badges23 bronze badges

Comments

Steve Chaloner · Accepted Answer · 2015-05-12 06:59:33Z

2

You can use \b to define the word boundary, so \baxe\b in this case.

x = x.replaceAll("\\baxe\\b");

answered May 12, 2015 at 6:59

Steve Chaloner

8,2021 gold badge25 silver badges38 bronze badges

Comments

Alvin Magalona · Accepted Answer · 2015-05-12 07:05:43Z

2

If you only want to replace the first occurrence, there is a method replaceFirst in String object.

String x = "axe pickaxe";
x = x.replaceFirst("axe", "sword");
System.out.print(x); //returns sword pickaxe

answered May 12, 2015 at 7:05

Alvin Magalona

7713 silver badges13 bronze badges

Collectives™ on Stack Overflow

Java - String replace exact word

6 Answers 6

1 Comment

Comments

5 Comments

Comments

Comments

Comments

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

6 Answers 6

1 Comment

Comments

5 Comments

Comments

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Linked

Related