Java字符串正则表达式匹配语法

Question

Can someone please explain why this won't work in Java but appears to in every other tool I have tested it on. The type of strings expected are similar to :a004871-5553:z05072-990

The expected outcome is to match the a0 at the beginning of the line.

String[] parts = nextLine[0].split(":");
String part1 = parts[1]; 
if (part1.matches("a[0-9]"))....

Answer 1

This line is the problem:

if (part1.matches("a[0-9]"))

Because String#matches matches the full input not just part of input

This should work though:

if (part1.matches("a[0-9-]+")) {...}