regular expression in java inside an if block

Question

I can see the below regular expression in the code ...

if (amount.matches("[-+]?[0-9]*\\.?[0-9]+")) return true;

now my query is that what this regular expression represent that amount should be numeric and what validation it will check

It is just checking if `amount` variable matches a signed decimal number. — anubhava, Nov 06 '14 at 06:10
@anubhava can you please share the example of i t also for example number would be -2345.76 like this — tuntutn sdsds, Nov 06 '14 at 06:11
It matches any of these numbers: `-2345.76`, `-2345`, `+2345.76`, `+2345`, `2345`, `-.76`, `+.76`, `.76` — anubhava, Nov 06 '14 at 06:15

score 1 · Answer 1 · answered Nov 06 '14 at 06:17

Your regex works like this :

       "[-+]?[0-9]*\\.?[0-9]+"
[-+]? --> either a `+` or `-` or nothing. Followed by
[0-9]* --> any number of digits (* implies greedy check). Followed by  
`\\.?` --> 0 or 1 `.` (matched literally. ). Followed by 
[0-9]+ --> one or more digits

demo here

regular expression in java inside an if block

1 Answers1