找出Java数组中不同的值

public void deltp(PrintWriter out) {
try{
PageData pd = new PageData();
pd = this.getPageData();

String delPath=pd.getString("delPath");
String allPath=pd.getString("allPath");
String updPath="";

List<String> list=new ArrayList<String>();
list.addAll(Arrays.asList(delPath.split(",")));


List<String> alllist=new ArrayList<String>();
alllist.addAll(Arrays.asList(allPath.split(",")));

for(int i=0;i<list.size();i++){
for (int j = 0; j < alllist.size(); j++) {
if(list.get(i).equals(alllist.get(j))){
alllist.remove(j);
}
}
}
for (int k = 0; k < alllist.size(); k++) {
updPath+=alllist.get(k)+",";
}

pd.put("updPath",updPath);
adInfoServiceImpl.delPurl(pd); //删除数据中图片数据
out.write("success");
}catch(Exception e){
e.printStackTrace();
}
out.close();
}