Sort alphanumeric string Java

I have this array to store the suffixes of some URLs added by the user:

[U2,U3,U1,U5,U8,U4,U7,U6]

When I do this:

for (Map<String,String> map : getUrlAttachments()) {
            String tmpId = map.get("id"); //it receives the U2,in the 1st iteration,then U3,then U1,...
            if (tmpId.charAt(0) == 'U') {
                tmpId.charAt(1);//2,then 3,then 1,...
                String url = map.get("url");
                String description = map.get("description");
                URLAttachment attachment;
                String cleanup = map.get("cleanup");
                if (cleanup == null && url != null && description != null) {
                    attachment = new URLAttachmentImpl();
                    attachment.setOwnerClass(FileUploadOwnerClass.Event.toString());
                    attachment.setUrl(url);
                    attachment.setDescription(description);
                    attachment.setOwnerId(auctionHeaderID);
                    attachment.setUrlAttachmentType(URLAttachmentTypeEnum.EVENT_ATTACHMENT);
                    attachment.setDateAdded(new Date());
                    urlBPO.save(attachment);

            }

My question:

I want to change the for condition by passing another list, which maps data sorted like [U1, U2, U6, U8]

I hope your help will know the best way I can do it

I want to create an array of IDS and sort them, but I don't know how to sort alphanumeric strings in Java

Solution

I decided to use the idea given by @ Abu, but I adapted it:

>I check the ID of the URL that the user is trying to add, > I delete the letter suffix in this ID, and then create an ArrayList to store the numeric part of each ID. > I sort the ArrayList like @ Abu, teach me in his answer, and then I verify each ID in the sorted ArrayList in the order it should be added

ArrayList <Integer> urlSorted = new ArrayList<Integer>();
//sort the url ids
for (Map<String,String> map : getUrlAttachments()) {
    String tmpId = map.get("id");
    if (tmpId.charAt(0) == 'U') {
        //gets the id,removing the prefix 'U'
        urlSorted.add( Integer.valueOf(tmpId.substring(1)));
    }
}
//sort the urlIds to check the sequence they must be added
Collections.sort(urlSorted);
//checks for each url id,compares if it's on the natural order of sorting to be added.
for(Integer urlId: urlSorted) {
    for (Map<String,String> map : getUrlAttachments()) {
        String sortedId = "U"+urlId;
        String tmpId = map.get("id");
        //compare the ids to add the 1,then 2,then 3...
        if (map.get("id").equals(sortedId)) {
                    //code to save according to the sorted ids.
        }
     }
}