Matching the pattern of a string in java

Question

I have been trying to figure out how to match the pattern of my input string with this kind of string:

"xyz 123456789"

In general every time I have a input that has first 3 characters (can be both uppercase or lowercase) and last 9 are digits (any combination) the input string should be accepted.

So if I have i/p string = "Abc 234646593" it should be a match (one or two white-space allowed). Also it would be great if "Abc" and "234646593" should be stored in seperate strings.

I have seeing a lot of regex but do not fully understand it.

An introduction to regular expressions in Java can be found here: docs.oracle.com/javase/tutorial/essential/regex — Nick Garvey
– Nick Garvey, Commented Jun 24, 2012 at 5:42
You can not learn regexes from randomly looking at examples. Take the time for in depth learning in one language, and later adopt it to similar syntaxes in other languages. — user unknown
– user unknown, Commented Jun 24, 2012 at 8:39

quux00 · Accepted Answer · 2012-06-24 13:33:03Z

4

Here's a working Java solution:

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

public class Regex {
  public static void main(String[] args) {
    String input = "Abc 234646593";

    // you could use \\s+ rather than \\s{1,2} if you only care that
    // at least one whitespace char occurs
    Pattern p = Pattern.compile("([a-zA-Z]{3})\\s{1,2}([0-9]{9})");
    Matcher m = p.matcher(input);
    String firstPart = null;
    String secondPart = null;
    if (m.matches()) {
      firstPart = m.group(1);  // grab first remembered match ([a-zA-Z]{3})
      secondPart = m.group(2); // grab second remembered match ([0-9]{9})
      System.out.println("First part: " + firstPart);
      System.out.println("Second part: " + secondPart);
    }
  }
}

Prints out:

First part: Abc
Second part: 234646593

edited Jun 24, 2012 at 13:33

answered Jun 24, 2012 at 4:29

quux00

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3 Comments

Nick Garvey Over a year ago

As a small note, with code like this, it is usually better /not/ to initialize firstPart and secondPart. That way, if you would accidently reference it later in the code without giving it a proper value, that error will be caught at compile time instead of runtime.

quux00 Over a year ago

I picked \\s{1,2} because the question said "one or two white-space allowed", so I was being strict to show him how to do it. Normally I would use \\s+ if I only care that there is at least one whitespace char and then any number after that.

user unknown Over a year ago

@midpeter444: I see, I was wrong. Now I ask myself why I didn't saw it, but that is of course not interesting for someone else, so I deleted my comment. Sorry.

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