public static void removeDuplicates(char[] str) {
		 if (str == null) return;
		 int len = str.length;
		 if (len < 2) return;
		
		int tail = 1;
		
		for (int i = 1; i < len; ++i) {
		 int j;
		 for (j = 0; j < tail; ++j) {
		 if (str[i] == str[j]) break;
		 }
		 if (j == tail) {
		 str[tail] = str[i];
		 ++tail;
		 }
		 }
		 str[tail] = 0;
		 
		 }