如何为以下情况编写正则表达式模式

Question

Can any body give me some regular expression patterns which will extract the version numbers(1.5) from some sample strings like

    "jdk1.5","jdk-v1.5","jdk-V1.5","jdk V1.5","jdkv1.5","jdk version1.5","1.5.6","v1.5","V1.5","version 1.5","Version 1.5","14.5.4","1.5.4","14.5.4""jdj14.5"

I want to store the regex patterns in a string array and will check these patterns with the above strings. If there is a match with any of the stored patterns, then the output should be the version number 1.5. I want to extract the version numbers (1.5) only from the above strings.

valid string formats : "jdk1.5","jdk-v1.5","jdk-V1.5","jdk V1.3","jdkv1.4","jdk version1.5","1.5.6","v1.5","V1.5","version 1.5","Version 1.5","14.5.4","1.5.4","14.5.4""jdj14.5","14.52.3.42"

Invalid String formats : "jdk1..2","jdk.1.2.",".1.2."

Answer 1

Try with:

^(jdk[- ]?)?([vV](ersion)? ?)?\d\.\d(\.\d)?$

You can ommit [vV] with v if you set CASE_INSENSITIVE flag.

Answer 2

Try this regular expression:

(?<=([\\w\\s]))(\\d)\\.(\\d)(.\\d)?

This will match all your valid formats , and not match any invalid format.

See it working here : http://regexr.com?31ubc

I would be grateful if someone can assist me in making it better, and also on how to make it match 1.5.6

Answer 3

Requirements

If you can formulize what you want as:

1. Anything in format 1.5 or 1.5.6 or 1.5.6.7 or 1.5.6.7.8 etc. is valid version number by default (numbers can be one or more digits like 12.60.70 ).
2. A version number 1.5 can be followed by a dot ( . ) only if it is in the format 1.5.6 .
3. A version number 1.5 never preceded by a dot ( . ) like .1.5 .

Solution

Then, I can suggest you this regex:

(?!\.)(\d+(\.\d+)+)(?![\d\.])

See it in action , includes all positive samples and excludes all negative samples you provided.

How to use

First capture group will be your version number. Sample code:

Pattern pattern    = Pattern.compile("(?!\\.)(\\d+(\\.\\d+)+)(?![\\d\\.])");
Matcher matcher    = pattern.matcher(inputStr);
boolean matchFound = matcher.find();

if (matchFound)
{
    String version = matcher.group(1);
    System.out.println("Version number: " + version);
}
else
{
    System.out.println("No match for the input!");
}

Note: This will work only with Java 7+, because look-aheads doesn't supported by older versions.

Answer 4

(?<![\\d.])(\\d+[.])+(\\d+)(?![\\d.])

Check this...

It will match the string of the form

number.number.number.number

not followed or preceded by a dot

Answer 5

对于1.5.6这样的字符串，您可以使用： [0-9](.[0-9])+ http://regexr.com?31ubo

Answer 6

Use the regex:

(^([jJ][dD][kK])([\s]*[vV]*\d+.\d+(.\d+)*))$

This would make your day :)

Answer 7

If you want to catch more than two numbers like "1.5.6" or "1.5.0" you can use

[0-9](.[0-9])+

Or if you only want the first two digits [0-9].[0-9] , but this will not work on strings like 1.5.0.0, it will catch 1.5 and 0.0.