I want to create to regular expression that allows all combinations of characters and digits and also dots but not a dot at the beginning. So valid strings could be "1.2.3" or "1.b.34d" or something. But I want to disallow strings like "." or ".1.2.3".

I'm trying with 

```
[^.]{0,1}[ a-zA-Z_\\-\\.0-9]*

```

but this doesn't work. Anyone any better idea?