用linkedHashMap保持输入顺序

public static void main(String[] args) {
Scanner sc = new Scanner(System.in);
String temp = sc.nextLine();
char[] result = temp.toCharArray();
LinkedHashMap map = new LinkedHashMap();
for (int i = result.length-1; i >=0 ; --i) {
if (!map.containsKey(result[i])){
map.put(result[i],"");
}
}
Iterator it = map.keySet().iterator();
while (it.hasNext()){
System.out.print(it.next());
}
}