Regex in Java matching specific special characters with number

I would like to have a regex which accepts numeric along with specific special characters (.-,). I just learned about basics of regex and I don't know how come my pattern doesn't work, really need advice.

.-,

My Pattern

^(([0-9]*)+[.,-]{0,1})$


(.,-) can only be repeated once, that's {0,1}. Also first should be numeric and last would also be numeric. I really need a little push.

.,-

{0,1}

Expected output

122-555-1521 //true

155--122 //false

155,- //false

.-12 //false

123.123. //false

.12 //false

1.2,1-3 //true


can you show us some expected outputs?
– YCF_L
Jun 29 at 9:10

You can use: ^d+(?:[.,-]d+)*$
– anubhava
Jun 29 at 9:15

^d+(?:[.,-]d+)*$

(OT: {0,1} is shorter, and more commonly, written ?.)
– Biffen
Jun 29 at 9:15

{0,1}

?

2 Answers
2

You can use the simple pattern ^(?:d+[.,-])*d+$

^(?:d+[.,-])*d+$

d+

.,-

[.,-]

(?:d[.,-])*

?:

d+

String array = {"122-555-1521", "155--122", "155,-", ".-12", "123.123."};
String pattern = "^(?:d+[.,-])*d+$";
for(String str : array){
System.out.println(str+" "+str.matches(pattern));
}

122-555-1521 true
155--122 false
155,- false
.-12 false
123.123. false


Working Demo - Regex Demo

'thanks for the answer with explanations of the patterns :) I;m very grateful thanks
– kenjiro jaucian
Jun 29 at 9:21

Better to use: ^(?:d+[.,-])*d+$
– anubhava
Jun 29 at 9:25

^(?:d+[.,-])*d+$

@anubhava better for ? If you don't care about capture or not-capture no need of ?:
– azro
Jun 29 at 9:26

?:

Better in terms of performance because ^(d+[.,-]?)*d+$ backtracks and takes many times more steps to complete due to ? quantifier. Check this demo and see # of steps taken Using non-capture group and not escaping dot inside character class are just minor improvements.
– anubhava
Jun 29 at 9:30

^(d+[.,-]?)*d+$

?

can i ask what is the use of that ?: and capture and not-capture? is there a difference
– kenjiro jaucian
Jun 29 at 9:32

If I understand correctly, you want to match groups of digits, separated by single non-digit characters from the set of [.,-]?

[0-9]+([.,-][0-9]+)*

sorry i can't use this cause it also accepts spaces
– kenjiro jaucian
Jun 29 at 9:31

You're right, I left out the ^ and $. However, azro's answer is more detailed and uses the more compact d, so better than mine anyway.
– WolfgangGroiss
Jun 29 at 9:53

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