CODEWITHSUNDEEP
javaregex
atul tripathi
atul tripathi

Reputation: 249

remove part of matcher after the match in regex pattern

I need to help in writing regex pattern to remove only part of the matcher from original string.

Original String: 2017-02-15T12:00:00.268+00:00

Expected String: 2017-02-15T12:00:00+00:00

Expected String removes everything in milliseconds.

My regex pattern looks like this: (:[0-5][0-9])\.[0-9]{1,3}

i need this regex to make sure i am removing only the milliseconds from some time field, not everything that comes after dot. But using above regex, I am also removing the minute part. Please suggest and help.

Upvotes: 2

Views: 5758

Answers (3)

koa73
koa73

Reputation: 881

Use $1 and $2 variable for replace

string.replaceAll("(.*)\\.\\d{1,3}(.*)","$1$2");

Upvotes: 1

Boschi
Boschi

Reputation: 630

Change your pattern to (?::[0-5][0-9])(\.[0-9]{1,3}), run the find in the matcher and remove all it finds in the group(1).

The backslash will force the match with the '.' char, instead of any char, which is what the dot represents in a regex.

The (?: defines a non-capturing group, so it will not be considered in the group(...) on the matcher.

And adding a parenthesis around what you want will make it show up as group in the matcher, and in this case, the first group.

A good reference is the Pattern javadoc: http://docs.oracle.com/javase/8/docs/api/java/util/regex/Pattern.html

Upvotes: 1

Wiktor Stribiżew
Wiktor Stribiżew

Reputation: 626738

You have defined a capturing group with (...) in your pattern, and you want to have that part of string to be present after the replacement is performed. All you need is to use a backreference to the value stored in this capture. It can be done with $1:

String s = "2017-02-15T12:00:00.268+00:00";
String res = s.replaceFirst("(:[0-5][0-9])\\.[0-9]{1,3}", "$1");
System.out.println(res); // => 2017-02-15T12:00:00+00:00

See the Java demo and a regex demo.

The $1 in the replacement pattern tells the regex engine it should look up the captured group with ID 1 in the match object data. Since you only have one pair of unescaped parentheses (1 capturing group) the ID of the group is 1.

Upvotes: 2

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