String deal(String s1, String s2){if(s1 != null){if(contact(s1.charAt(s1.length() - 1)) == 1){s1 += s2;return s1;}else{s1 = s1.substring(0, s1.length() - 1);deal(s1, s2);}}return s1;}int contact(char ch){if(Character.isDigit(ch) || ch == *(* || ch == *)* || ch == *.*)return 1;if(ch == *-* || ch == *+*)return 2;return 0;}String str = deal("800", "*");這樣就返回的是800*如果String str = deal("800-", "*");返回的是800，不是800*是不是意思就是返回的是第一次的返回值？