for循环中的for循环 - ListArrays - Android，Java！

Question

This is a noob question but I have to ask it anyway because I think I'll go crazy soon.

What I want to achieve is a ListView that populates by twitter and this I have implemented, the two ListArray s gets populated by the tweet and the picture URL. This is successful, but when I refresh twitter the new pile of twitter gets below the old ones.

I could simply clear the ListArrays but then all the twitter disappears in the list which is not desirable, I simply want to add only the new tweets, and make the new tweets get on top of the list.

So I guess this is a two fold question

1. How do I make the list only to add which is not there?, and
2. How do I make the latest tweet appear on top?

Could really use some great input, the code below is the most essential part of the (messy) code, which is the refresh method.

public void updateTwitter(){

        twitter = new TwitterFactory().getInstance();

        try {
            QueryResult result = twitter.search(new Query(TWEETQUERY));
            tweets = result.getTweets();
            for (Tweet tweet : tweets) {
                String tweetProfile = tweet.getProfileImageUrl();
                String twwwwww = tweet.getText();
                for(String tww : tweetString){

                    if(tww.equals(twwwwww)){
                        System.out.println("Not added");
                    } else {
                        tweetString.add(twwwwww);
                        urlArray.add(tweetProfile);
                    }
                }
            }
            if(adapter != null) {
                tweetList.setAdapter(adapter);
                System.out.println("adapter sets, not created");
            } else {
                adapter = new LazyAdapter(this, urlArray, tweetString);
                tweetList.setAdapter(adapter);
            }
        } catch (TwitterException te) {
            te.printStackTrace();
            System.out.println("Failed to search tweets: " + te.getMessage());
        }
    }

Answer 1

创建一个从BaseAdapter扩展并调用notifyDataSetChanged（）的适配器。

Answer 2

It sounds like you really want a set, not a list, and be able to traverse it according to some criteria (time added, in this case). Perhaps a SortedSet would be appropriate?

The implementation would be something like this:

/* SortedSet<Tweet> tweets defined somewhere above, possibly with a custom Comparator */

public void updateTwitter()
{
   try
   {
       tweets.addAll(TwitterFactory.getInstance().search(query).getTweets());
   } catch (TwitterException te) {
       te.printStackTrace();
       System.out.println("Failed to search tweets: " + te.getMessage());
   }
}

Answer 3

Presumably, the LazyAdapter derives from BaseAdapter and is backed by urlArray . If so, to have tweets appear on top, you need to add them to the beginning of the array.

Use add(0, newEntry) to add to the beginning of the array and notifyDataSetChanged() to tell the adapter to post the updates .

A couple of other notes:

1) Its unclear to me what you intend, especially seeing code like twww.equals(twwwwwww) . It seems like you're maintaining the old tweets and trying to only add new ones, but with unclear variable names like twww, twwwwww, and tweetString , I can only guess.

2) You shouldn't have to keep setting the adapter. Once the relationship between the listview, adapter, and backing array is set, you should only have to update the array and notify the adapter.