Reorder Data in Log Files

给一个log文件, 里面有两种log, 一个是全是字符, 一个是全是数字. 要求排序, 全是字符的按照字符的字典序排序, 全是数字的维持不变.

public class Solution {
    public static String[] reorderLogFiles(String[] logs) {
        Comparator<String> comparator = new Comparator<String>() {
            @Override
            public int compare(String o1, String o2) {
                String[] s1 = o1.split(" ", 2);
                String[] s2 = o2.split(" ", 2);
                boolean isDigit1 = Character.isDigit(s1[1].charAt(0));
                boolean isDigit2 = Character.isDigit(s2[1].charAt(0));
                if (!isDigit1 && !isDigit2) { // if both string are not number
                    if (s1[1].compareTo(s2[1]) != 0) { // if content is diff
                        return s1[1].compareTo(s2[1]);
                    }
                    else {  // compare the id
                        return s1[0].compareTo(s2[0]);
                    }
                }
                else {
                    if (isDigit1 && isDigit2) {
                        return 0;
                    }
                    else if (isDigit1){
                        return 1;
                    }
                    else{
                        return -1;
                    }
                }
            }
        };
        Arrays.sort(logs, comparator);
        return logs;
    }
}