比较两个字符串的大小
static int compareTo(String s1, String s2) { int len1 = s1.length(); int len2 = s2.length(); int lim = Math.min(len1, len2); char[] charS1 = s1.toCharArray(); char[] charS2 = s2.toCharArray(); int k = 0; while (k < lim) { char c1 = charS1[k]; char c2 = charS2[k]; if (c1 != c2) return c1 - c2; k++; } return len1 - len2; }