simple using replaceAll()
using ^\\d+|\\d+$
regex that looks for digits in the beginning and ending of the line.
System.out.println("1adfds23dfdsf121".replaceAll("^\\d+|\\d+$", ""));
output:
adfds23dfdsf
EDIT
Regex explanation:
^ Start of line
\d+ Any digit (one or more times)
| OR
\d+ Any digit (one or more times)
$ End of line
3
solved How to remove numbers from string which starts and ends with numbers?