Numbers from string

Question

public void check(String str){
    for(int i =0; i<str.length(); i++){
    //Print only the numbers    
    }
}

In that for loop I want to be able to look through the string and find just the first two numbers. How do I do that?

Example:

str= 1 b 3 s 4

Print: 1 3

'1 b 23 s 5' should print what? '1 23' or '1 2'? Does the spacing matter? Or you can just print 12? — Rogel Garcia, Jan 26 '14 at 03:18
Related work http://stackoverflow.com/questions/2367381/extract-numbers-from-a-string-java http://stackoverflow.com/questions/13440506/java-find-all-numbers-in-the-string-need-check — Jarek Huang, Jan 26 '14 at 03:27

Paul Draper · Accepted Answer · 2014-01-26T03:36:17.467

1

This works for numbers that are more than one digit.

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

public void check(String str) {
    Matcher m = Pattern.compile("\\d+").matcher(str);
    for(int n = 0; n < 2 && m.find(); n++)  {
        System.out.println(m.group());
    }
}

Explanation:

\d+ (written in a String literal as "\\d+") is a regular expression that matches one or more digits.

m.find() finds the next match, returning whether it found the match.

m.group() returns the matched substring.

edited Jan 26 '14 at 03:36

answered Jan 26 '14 at 02:59

Paul Draper

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Do this go in the for loop? – user243872 Jan 26 '14 at 03:01
@user243872, I added the method signature to make this more clear. – Paul Draper Jan 26 '14 at 03:05
@user243872, do you have an extra for loop? – Paul Draper Jan 26 '14 at 03:13
oh haha ya.. my bad. But what if the string sent in is just letters. example: aaaaa – user243872 Jan 26 '14 at 03:15
@user243872, then it is impossible to print two numbers. What do you want to happen in that case? An exception? Printing as many numbers as are present, but no more than two? – Paul Draper Jan 26 '14 at 03:16
I just want it to be able to get the first two numbers and if there are no numbers in the string to just skip it and not do anything with it. – user243872 Jan 26 '14 at 03:23

Numbers from string

1 Answers1