Regular expression not excluding a single negative symbol in isnumeric function.

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Javascript

Java

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I'm trying to accept a string in a function and check if it's a valid numeric. If it is valid, the function returns True, else False. The valid patterns are:

1) 1234567890.9876543210
2) -1234567890.9876543210
3) -0123456789
4) 9876543210
5) .1234567890
6) 1234567890.25
7) -.1234567890
8) 0

All other patterns should be treated as invalid.

However, if only the negative symbol (-) is supplied, the function still treats it as valid, which goes against my requirement specification. So, how do I ensure that whenever a negative symbol is typed, it must be followed by a digit, or a decimal point followed by a digit? Otherwise, there shouldn't be any negative symbol at all. The user can't supply only the negative symbol. Besides, all the eight patterns listed above should also be counted as valid.

Regards

What I have tried:

private boolean isNumeric(String value) {
    String pattern = "^(-?(\\d+)?(\\.\\d+)?)$";
    return (value != null && !value.equals("") && value.matches(pattern));
}