java8 新用法

/**
 * 得到优先级最高的集合
 * @param list es查询结果
 * @return
 */
public List<Group> getMaxPriorityGroup(List<Group> list) {
    int maxPriority = list.stream().max((o1, o2) -> o1.getPriority() - o2.getPriority()).get().getPriority();
    return list.stream().filter(x -> x.getPriority() == maxPriority).collect(Collectors.toList());
}

/**
 * 跟据优先级排序,优先级相同的则随机
 * @param campaignList es查询集合
 * @return
 */
@Override
public List<EsCampaign> sortByPriority(List<EsCampaign> campaignList) {
    if(campaignList.size()==0){
        return campaignList;
    }

    Random random = new Random();
    campaignList.stream().map(x -> {
        x.setCampaignPriority(x.getCampaignPriority() * 1000 + random.nextInt(999));
        return x;
    }).collect(Collectors.toList());

    campaignList.sort((EsCampaign a, EsCampaign b) -> b.getCampaignPriority() - a.getCampaignPriority());

    //list.parallelStream().sorted(Comparator.comparing(Group::getPriority)).collect(Collectors.toList()).forEach(System.out::println);另一种排序方法 。

    return campaignList;
}

public Map<String, List<Article>> groupByAuthor() { 

    return articles.stream()

        .collect(Collectors.groupingBy(Article::getAuthor));

}