public static void main(String[] args) { String s = "aaaa......bbbb....ccc...dddddd"; String s2 = s.replaceAll("\.+",""); System.out.println(s2); // s2:aaaabbbbcccdddddd String s3 = s2.replaceAll("(.)\1+","$1"); // $1代表第一组中的内容 System.out.println(s3); //s3:abcd }