Использование [A-Ha-h][1-8] [A-Ha-h][1-8]
Демонстрация:
public class Main {
public static void main(String[] args) {
// Tests
String[] testStrs = { "e2 e4", "a1 a3", "1a e4", "a1 4e", "12 34", "ab cd", "e2e4", "e1 e4", "x1 y2", "e0 e4",
"e1 e9", "e2 x1", "x1 e2" };
for (String s : testStrs) {
if (s.matches("[A-Ha-h][1-8] [A-Ha-h][1-8]")) {
System.out.println(s + " <-passed");
} else {
System.out.println(s + " <-failed");
}
}
}
}
Выход:
e2 e4 <-passed
a1 a3 <-passed
1a e4 <-failed
a1 4e <-failed
12 34 <-failed
ab cd <-failed
e2e4 <-failed
e1 e4 <-failed
x1 y2 <-failed
e0 e4 <-failed
e1 e9 <-failed
e2 x1 <-failed
x1 e2 <-failed