Question

I am trying to check if a string is “0”, “1”, “2”, … , “9” without converting the string to a number. Any suggestions? Right now I’m doing a .equals( ) for each and it’s ugly.

Answer 1

You can use a regular expression to
do this. The pattern \d should work, it means match a single digit. In Java you have to escape the backslash so it becomes \\d.

String str = "4";

str.matches("\\d"); // true