How to extract a number from a string in a particular format?

Question

I have a String like this as shown below. From below string I need to extract number 123 and it can be at any position as shown below but there will be only one number in a string and it will always be in the same format _number_

text_data_123
text_data_123_abc_count
text_data_123_abc_pqr_count

text_tery_qwer_data_123
text_tery_qwer_data_123_count
text_tery_qwer_data_123_abc_pqr_count

Below is the code:

String value = "text_data_123_abc_count";   

// this below code will not work as index 2 is not a number in some of the above example
int textId = Integer.parseInt(value.split("_")[2]);

What is the best way to do this?

You should define "best". You could use a regexp or a removal — user180100
– user180100, Commented Aug 12, 2015 at 18:17

user180100 · Accepted Answer · 2015-08-12 18:22:50Z

1

With a little guava magic:

String value = "text_data_123_abc_count";
Integer id = Ints.tryParse(CharMatcher.inRange('0', '9').retainFrom(value)

Comments

vks · Accepted Answer · 2015-08-12 18:17:19Z

1

\\d+

this regex with find should do it for you.

answered Aug 12, 2015 at 18:17

vks

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1 Comment

Wiktor Stribiżew Over a year ago

@ThaNet: This is Java, not C#.

Avinash Raj · Accepted Answer · 2015-08-12 18:30:20Z

1

Use Positive lookahead assertion.

Matcher m = Pattern.compile("(?<=_)\\d+(?=_)").matcher(s);
while(m.find()) 
{
System.out.println(m.group());
}

edited Aug 12, 2015 at 18:30

answered Aug 12, 2015 at 18:17

Avinash Raj

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Comments

Wiktor Stribiżew · Accepted Answer · 2015-08-12 19:07:28Z

1

You can use replaceAll to remove all non-digits to leave only one number (since you say there will be only 1 number in the input string):

String s = "text_data_123_abc_count".replaceAll("[^0-9]", "");

See IDEONE demo

Instead of [^0-9] you can use \D (which also means non-digit):

String s = "text_data_123_abc_count".replaceAll("\\D", "");

Given current requirements and restrictions, the replaceAll solution seems the most convenient (no need to use Matcher directly).

edited Aug 12, 2015 at 19:07

answered Aug 12, 2015 at 19:01

Wiktor Stribiżew

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Comments

Oscarmageddon · Accepted Answer · 2015-08-12 19:00:40Z

0

u can get all parts from that string and compare with its UPPERCASE, if it is equal then u can parse it to a number and save:

public class Main {

public static void main(String[] args) {

    String txt = "text_tery_qwer_data_123_abc_pqr_count";

    String[] words = txt.split("_");

    int num = 0;

    for (String t : words) {
        if(t == t.toUpperCase())
            num = Integer.parseInt(t);
    }

    System.out.println(num);
}

}

answered Aug 12, 2015 at 19:00

Oscarmageddon

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2 Comments

Wiktor Stribiżew Over a year ago

This will fail in case there is a word in ALLCAPS.

Oscarmageddon Over a year ago

then u can edit the if: if(t == t.toUpperCase() && t == t.toLowerCase()) all is part of the imagination...

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