该活动包含一个编辑文本，提交按钮和一个从服务器获取其数据的列表视图。当我单击“编辑文本”时，它会按预期滚动到底部：
editText.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
getWindow().setSoftInputMode(
WindowManager.LayoutParams.SOFT_INPUT_ADJUST_PAN);
scrollMyListViewToBottom();
Log.i("yoyo","ListSize Before: " + size);
}
});
但是，当我单击“提交”按钮，并且在调用
notifydatasetchanged();的列表视图更新后，它不会滚动到底部。如果您想知道CommentQuery();中会发生什么，我可以提供更多代码。 submitComment.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
commentItem = new ParseObject("CommentItem");
commentItem.put("parentUser", feedUserName);
commentItem.put("parentFeed", feedItem);
// commentItem.put("parentObjectId", objectId);
commentItem.put("commentText", String.valueOf(commentText.getText()));
commentItem.put("username", ParseUser.getCurrentUser().getUsername());
commentItem.put("country", ParseUser.getCurrentUser().getInt("country"));
commentItem.put((ParseUser.getCurrentUser().getUsername() + "globalPoints"), 0);
commentItem.put("parentObjectId", objectId);
replies +=1;
commentItem.saveInBackground(new SaveCallback() {
@Override
public void done(ParseException e) {
if (e == null) {
arrayCommentList.clear();
comments.clearCachedResult();
CommentQuery();
customCommentListViewAdapter.notifyDataSetChanged();
Log.i("yoyo","ListSize After: " + size); //size changes like it is supposed to
scrollMyListViewToBottom(); //doesn't do anything
}
}
});
}
});
scrollMyListViewToBottom（）函数：
public void scrollMyListViewToBottom() {
commentList.post(new Runnable() {
@Override
public void run() {
// Select the last row so it will scroll into view...
commentList.setSelection(size);
}
});
}
CommentQuery函数：
public void CommentQuery(){
comments = new ParseQuery<>("CommentItem");
comments.setLimit(99);
comments.whereEqualTo("parentObjectId", objectId);
comments.findInBackground(new FindCallback<ParseObject>() {
@Override
public void done(List<ParseObject> mobjects, ParseException e) {
if(e == null){
for(ParseObject object : mobjects){
parseObs = mobjects;
size = parseObs.getsize();
commentData = new HashMap<>();
commentData.put("username", object.getString("username"));
commentData.put("feed", object.getString("commentText"));
commentData.put("likes", String.valueOf(object.getInt("likes")));
commentData.put("country", String.valueOf(object.getInt("country")));
commentData.put("replies", String.valueOf(0));
commentData.put("global", String.valueOf(object.getInt(usernameText+"globalPoints")));
arrayCommentList.add(commentData);
}
customCommentListViewAdapter = new CustomCommentListViewAdapter(getApplicationContext(), arrayCommentList);
commentList.setAdapter(customCommentListViewAdapter);
}
}
});
}
最佳答案
首先-不要这样做。 parseObs = mobjects;您使用parseObs设置的任何适配器都失去了对该列表的引用。
相反，您需要这样做。
parseObs.clear();
parseObs.addAll(mobjects);
接下来，
size = parseObs.getsize();绝对不需要在循环内。遍历列表时，列表的大小不应更改。最后，这已经在解析回调中完成了您想要的操作
customCommentListViewAdapter = new CustomCommentListViewAdapter(getApplicationContext(), arrayCommentList);
commentList.setAdapter(customCommentListViewAdapter);
您无需再次通知适配器。
CommentQuery();
// customCommentListViewAdapter.notifyDataSetChanged(); // Not necessary
那么，
CommentQuery是异步的。arrayCommentList.clear(); // List is now empty
...
CommentQuery(); // doing stuff ... in the background
..
scrollMyListViewToBottom(); // there isn't anything to scroll to yet!
基本上，解决方法是在
scrollMyListViewToBottom()的CommentQuery()方法块中的done { }，这将在ListView包含数据之后。而且，正如我在评论中所说，
size不必作为变量。只需使用customCommentListViewAdapter.getCount()