在java中获取List集合中最大的日期时间操作

} else {
 
/** 获取此专题下的所有内容的最新时间 */
Long featureId = this.communityFeatureMapper.selectFeatureIdByLabelId(labelId);
List<CommunityFeatureRelation> communityFeatureRelationList = this.communityFeatureRelationMapper.selectByFeatureId(featureId);
List<Date> dateList = Lists.newArrayList();
for (CommunityFeatureRelation communityFeatureRelation : communityFeatureRelationList) {
	CommunityProduct communityProduct =this.communityProductMapper.selectContentIdByProductIdAndType(communityFeatureRelation.getProductId(),BaseConstans.ARTICLE_YIFABU);
	CommunityArticle communityArticle = this.communityArticleMapper.selectByPrimaryKey(communityProduct.getContentId());
	dateList.add(communityArticle.getReleaseTime());
 }
if (!CollectionUtils.isEmpty(dateList)) {
	Date max = Collections.max(dateList);
	/** 内容->添加专题-此专题下的合伙人getReleaseTime 更新, 若此专题下不存在合伙人, 则不更新 */
	Long productId = this.communityProductMapper.selectIdByContentIdAndType(featureId, BaseConstans.FOUR);
	CommunityPartner communityPartner = this.communityPartnerMapper.selectByPartnerId(productId);
	if (!StringUtils.isEmpty(communityPartner)) {
		communityPartner.setCreateTime(max);
		communityPartnerMapper.updateByPrimaryKeySelective(communityPartner);
 }
}
 
 CommunityProduct communityProduct = this.communityProductMapper.selectContentIdByProductIdAndType(prodId, proType);

//待排序的集合
List<String> list=new ArrayList<String>();
list.add("2019-06");
list.add("2019-11");
list.add("2019-02");
list.add("2019-09");
list.add("2019-05");
//自定义list排序，集合数据(月份)按升序排序;
final SimpleDateFormat sdft = new SimpleDateFormat("yyyy-MM");
Collections.sort(list, new Comparator<String>(){
  @Override
 public int compare(String month1, String month2) {
 int mark = 1;
 try {
   Date date1 = sdft.parse(month1);
   Date date2 = sdft.parse(month2);
   if(date1.getTime() < date2.getTime()){
    mark = -1;//调整顺序,-1为不需要调整顺序;
   }
   if(month1.equals(month2)){
    mark = 0;
 }
 } catch (ParseException e) {
  LOG.error("日期转换异常", e);
  e.printStackTrace();
 }
 return mark;
 } //compare
});

Date() date1=new Date();
Date() date2=new SimpleDateFormat("yyyy-MM-dd").parse("2019-06-11");
Boolean flag;
if(date1.before(date2)){
 flag=true;
}
a.before(b)；该方法是判断a日期是否小于b日期，返回的是一个布尔类型结果。