迭代器及匿名内部类和 List何时用new何时用null-优快云博客

本文详细介绍了如何根据用户ID构建应用页面列表，并通过获取朋友的播放记录来展示页面，同时实现页面列表的排序功能。

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/**
     * 根据appPageList包装page展示列表
     * 
     * @param appPageList
     */
    protected void buildAppPageList(int userId, AppPageResult appPageResult) {
        int size = appPageResult.getCount();
        if (appPageResult != null && size > 0) {
            List<Integer> pageIdList = new ArrayList<Integer>();
            for (AppPage appPage : appPageResult.getAppPageList()) {
                pageIdList.add(appPage.getId());
            }

            List<UserPlayFlowResult> friendIdList = null;
            if(!CollectionUtils.isEmpty(pageIdList)){
                friendIdList = userPlayService.getFriendPlayByPageIds(userId, pageIdList, EXPIRED_DAYS);
            }

            if(!CollectionUtils.isEmpty(friendIdList)){
                for (AppPage appPage : appPageResult.getAppPageList()) {
                    int pageId = appPage.getId();
                    for (Iterator<UserPlayFlowResult> iterator = friendIdList.iterator(); iterator.hasNext();) {
                        UserPlayFlowResult userPlayFlowResult = (UserPlayFlowResult) iterator
                                .next();
                        if(pageId == userPlayFlowResult.getPageId()){
                            int friendCount = userPlayFlowResult.getFriends().size();
                            if (friendCount > 0) {
                                String friends = getFriendsNameAndCount(userPlayFlowResult.getFriends().subList(0, 2), friendCount);
                                appPage.setFriends(friends);
                            }
                            iterator.remove();
                        }
                    }
                }
            }
        }
    }

2、


sort(appPageList, new ComparatorAppPage() {

            @Override
            public int compare(AppPage page0, AppPage page1) {
                int compareOrder = 0;
                //如展示顺序相同则比较更新时间
                if (page0.getAddTime() != null && page1.getAddTime() != null) {
                    compareOrder = page0.getAddTime().compareTo(page1.getAddTime());
                    if (compareOrder == 0) {
                        return compare(page0.getDisplayOrder(), page1.getDisplayOrder());
                    } else {
                        return compareOrder;
                    }
                } else {
                    return -1;
                }
            }
        });

3、


List<Integer> pageIdList = new ArrayList<Integer>();
            for (AppPage appPage : appPageResult.getAppPageList()) {
                pageIdList.add(appPage.getId());
            }

            List<UserPlayFlowResult> friendIdList = null;
            if(!CollectionUtils.isEmpty(pageIdList)){
                friendIdList = userPlayService.getFriendPlayByPageIds(userId, pageIdList, EXPIRED_DAYS);
            }