小编Abh*_*ary的帖子

我需要使用lambda表达式迭代HashMap的HashMap并过滤掉一些不需要的条目.我尝试了一些方法,但似乎没有用.以下是地图的结构.

Map<String, Map<Date, String>> sensor_tags = new HashMap<String, Map<Date,String>>();

从这张地图中,我需要删除传感器数据早于特定日期的条目(日期是内部地图的关键).以下是地图sensor_tags-的示例数据

String tagName = "zoneSensor";
Map<Date, String> values= new HashMap<Date, String>();

// (1st entry for tag 1) --> date is day before yesterday
Calendar datekey1 = Calendar.getInstance();
datekey1.set(2018, 12, 01, 12, 30, 45);
values.put(datekey1.getTime(), "ON");

// (2nd entry for tag 1) --> date is yesterdys date
Calendar datekey = Calendar.getInstance();
datekey.set(2018, 12, 02, 12, 30, 45);
values.put(datekey.getTime(), "OFF");

// (3rd entry for tag 1) --> date is today
Calendar instance = …