凯撒加密，用队列为什么输出的是一串数字求问

Question

public class Codes { public static void main(String[] args){ int [] key={5,12,-3,8,-9,4,10}; Integer keyvalue; String encoded=null,decoded=null; String message="dasdasdasdasdasdafdf"; Queue<Integer> encodingQueue=new LinkedList<Integer>(); Queue<Integer> decodingQueue=new LinkedList<Integer>();   for(int i=0;i<key.length;i++){  encodingQueue.add(key[i]);   } for(int j=0;j<message.length();j++){  keyvalue=encodingQueue.remove();  encoded+=(char)message.charAt(j)+keyvalue;  encodingQueue.add(keyvalue); } System.out.println(encoded);