import java.util.regex.Matcher;
import java.util.regex.Pattern;
public class Main {
public static void main(String[] args) {
System.out.println(isNumber("1001-5226656555"));
}
public static String isNumber(String s) {// 提取一个区号
String regex = "^(\\d{1,4})\\-(\\d{5,})$";
Pattern p = Pattern.compile(regex);
Matcher m = p.matcher(s);
if (m.matches()) {
return m.group(1);
}
return null;
}
}
结果：1001
