regex pattern to match 2.9.1, 2.9.2, 3.9.1, 3.9.2 and onwards

[Jacob Sonia]

if i try [2-9][1-9][1-9], in that case 2.1.1 will match, but i want to match the only conditions mentioned in the subject

[Mike. J. Thompson]

Well your second number should not match 1-9, it should only match 9.

And your third number should not match 1-9, it should only match 1-2 (if that is what you meant).

[Jacob Sonia]

Actually the real problem is that the following should match
2.9
2.9.1
2.9.2
and so on
3.1
3.1.1
3.2.1
so from 3 onwards any digit could match
but for ones starting with 2, the only digit allowed next is 9

[Mike. J. Thompson]

Well that is somewhat more complicated!

I would write a regular expression that matches only numbers that begin with 2, and then write a separate one that matches only numbers beginning with 3. I believe you can then combine them with a boolean or operator.

[Jacob Sonia]

The starting string is Android/2.9.1
so i tried to do this but it is not printing the right result

public class RegexTester {

	/**
	 * @param args
	 */
	public static void main(String[] args) {
		 Pattern pattern = Pattern.compile("eBayAndroid/[2-9].[9](.[1-9])?");
		 Matcher matcher = pattern.matcher("eBayAndroid/2.9.9");
		 System.out.println("Input String matches regex - "+matcher.matches()); //print true
		  matcher = pattern.matcher("eBayAndroid/2.9.9");
		 System.out.println("Input String matches regex - "+matcher.matches()); //print true
		 matcher = pattern.matcher("eBayAndroid/3.1.9");
		 System.out.println("Input String matches regex - "+matcher.matches()); //print true
                 matcher = pattern.matcher("eBayAndroid/2.1.9");
		 System.out.println("Input String matches regex - "+matcher.matches()); //print false

		

	}

}

[Mike. J. Thompson]

That is because that regular expression requires the second digit to be 9, but you only require that if the first digit was a 2.

Try what I suggested above.

[Jacob Sonia]

How will you combine it..this doesn't work

import java.util.regex.Matcher;
import java.util.regex.Pattern;


public class RegexTester {

	/**
	 * @param args
	 */
	public static void main(String[] args) {
		 Pattern pattern1 = Pattern.compile("eBayAndroid/[2-9].[9](.[1-9])?");
		 Pattern pattern2 = Pattern.compile("eBayAndroid/[3-9].[1-9](.[1-9])?");
		 Pattern pattern = Pattern.compile(pattern1.pattern() + pattern2.pattern());
		 Matcher matcher = pattern.matcher("eBayAndroid/2.9.9");
		 System.out.println("Input String matches regex - "+matcher.matches());
		  matcher = pattern.matcher("eBayAndroid/2.9.9");
		 System.out.println("Input String matches regex - "+matcher.matches());
		 matcher = pattern.matcher("eBayAndroid/3.1.9");
		 System.out.println("Input String matches regex - "+matcher.matches());
		

	}

}

[Mike. J. Thompson]

You combine them with the boolean or operator (the pipe symbol)

So "(b|c)at" will match bat or cat, but not tat.

[Jacob Sonia]

Thanks Mike, this helped. I didn't know about how we could merge two regex patterns.

[Darryl Burke]

Also note that the dot is a metacharacter in regex and matches any character. To match a literal dot, you need to escape it.

\.
// or, in a String literal
"\\."

[Stefan Evans]

It looks like you have a semantic version numbering system and you are defining a range of versions.

I just have to raise the question : Is using a regular expression the right tool here?
What are you trying to accomplish with this?