Checking characters in string in Java

Question

I am creating a validator for inputs on one of my text fields in java. The length of the input field should be 10 and the values should be any number in between 1-9. The catch is, the input should use the same character only 10x... So valid values should be such as the following:

But if the entered text is something like 111111112, this should be considered as invalid entry.

Currently I use String.matches("^[0-9]+$") to check if the inputted values are valid but this still accepts 111111112 as valid. What is the correct approach to check if all 10 characters of the string is the same?

sshashank124 · Accepted Answer · 2014-06-29 07:48:44Z

5

You can do it using back referencing:

String.matches("^([0-9])\1{9}$")

or:

String.matches("^([0-9])\\1{9}$")

DEMO

This only matches exactly 10 digits in a line that are all the same.

answered Jun 29, 2014 at 7:48

sshashank124

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3 Comments

zx81 Over a year ago

That was fast, sshashank! +1 :)

sshashank124 Over a year ago

@zx81, Thank you. :). We meet again

zx81 Over a year ago

Now you made me laugh... Thanks for that. :) Catch you later, starting to watch a show.

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