How can I get number from String with endWith function effectively and with clear code?

Question

I have inputs like "Test1","Test2"... and I just try to find end number in these strings. I wrote below code but I don't like it. How can I improve this code? Is there any advice?

 private int getEndNumber(final String str) {
    if (str.endsWith("1")) {
      return 1;
    } else if (str.endsWith("2")) {
      return 2;
    } else if (str.endsWith("3")) {
      return 3;
    } else if (str.endsWith("4")) {
      return 4;
    } else if (str.endsWith("5")) {
      return 5;
    } else if (str.endsWith("6")) {
      return 6;
    } else if (str.endsWith("7")) {
      return 7;
    } else {
      return 0;
    }
  }

Can the number be more than one digit? – TiiJ7 Jan 14 '19 at 14:16 — TiiJ7, Jan 14 '19 at 14:16
Yes, numbers can be more than one digit. – Sha Jan 14 '19 at 14:21 — Sha, Jan 14 '19 at 14:21
Why is `8` and `9` missing? – Jaroslaw Pawlak Jan 14 '19 at 15:39 — Jaroslaw Pawlak, Jan 14 '19 at 15:39

score 3 · Answer 1 · answered Jan 14 '19 at 14:16

3

One liner - return last character:

return Integer.parseInt(str.substring(str.length() - 1)));

If you want to return 0 also when ends with 8 or 9 you will need to add a bit logic to it

answered Jan 14 '19 at 14:16

Ori Marko

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score 2 · Accepted Answer · answered Jan 14 '19 at 14:16

2

Regex is your friend.

Pattern p = Pattern.compile("[0-9]+$"); // This regex matches the last number
Matcher m = p.matcher(str); // Create the matcher

//If the pattern matches then we get the matching string
if(m.find()) { 
    result = m.group();
}

You can alternatively iterate the string in reverse and check if the characters are integers, but that's rather tedious than using regexes.

There's a nice article about regexes here http://www.vogella.com/tutorials/JavaRegularExpressions/article.html

You read it thoroughly and forget everything in a few days, like the most of us :-).

answered Jan 14 '19 at 14:16

Thihara

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1

Instead of [0-9] you can also just use \\d :) – N4zroth Jan 14 '19 at 14:49
@N4zroth Yeah, but I figured OP would read 0-9 easier than \d because he's apparently new to regexes – Thihara Jan 14 '19 at 23:09

Prashant Zombade · Answer 3 · 2019-01-14T15:50:28.840

0

Extension from @user7294900 but multi-liner. In case you do not want to use regex.

    private int getEndNumber(final String str) {
        Integer num = 0;
        try {
            num =  Integer.parseInt(str.substring(str.length() - 1)) ; 
            num = num >= 7 ? 0 : num;
        } catch (NumberFormatException ex) {
            num = 0;
        }
        return num;
    }

edited Jan 14 '19 at 15:50

answered Jan 14 '19 at 15:33

Prashant Zombade

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15

How can I get number from String with endWith function effectively and with clear code?

3 Answers3