我正在尝试使用HashMap将事件列表分组到日期中,但我在实现它时遇到了问题。我希望日期是关键,而事件将是价值观。因此,与键匹配的每个事件都将存储在HashMap中的List中。到目前为止,我有一个事件列表和一个列表日期.....我的代码如下所示,提前感谢。
码
public class TestMap {
public static void main(String[] args){
TestMap test = new TestMap();
List<Date> mDays = new ArrayList<Date>();
SimpleDateFormat mFormat = new SimpleDateFormat("EEEE d MMMM yyyy");
GregorianCalendar mCalendar = (GregorianCalendar)GregorianCalendar.getInstance();
mCalendar.setTime(new Date());
for (int i = 0; i < 7; i++){
mDays.add(mCalendar.getTime());
mCalendar.add(Calendar.DAY_OF_WEEK, 1);
System.out.println("Date: " + mFormat.format(mDays.get(i)));
}
List<Events> mEvents = new ArrayList<Events>();
mEvents.add( new Events("1", "boat party", "Sunday 7 December 2014"));
mEvents.add( new Events("2", "church meeting", "Monday 8 December 2014"));
mEvents.add( new Events("3", "shopping", "Saturday 13 December 2014"));
mEvents.add( new Events("4", "clubbing", "Friday 12 December 2014"));
mEvents.add( new Events("5", "visiting", "Thursday 11 December 2014"));
mEvents.add( new Events("6", "tour", "Wednesday 10 December 2014"));
mEvents.add( new Events("7", "work", "Tuesday 9 December 2014"));
mEvents.add( new Events("1", "beckie birthday", "Sunday 7 December 2014"));
mEvents.add( new Events("2", "camping", "Monday 8 December 2014"));
mEvents.add( new Events("3", "gym", "Saturday 13 December 2014"));
mEvents.add( new Events("4", "working", "Friday 12 December 2014"));
mEvents.add( new Events("5", "farming", "Thursday 11 December 2014"));
mEvents.add( new Events("6", "attend sales", "Wednesday 10 December 2014"));
mEvents.add( new Events("7", "work", "Tuesday 9 December 2014"));
for(Events evt: mEvents){
System.out.println("ID: " +evt.getEventId()+ " Title: "+evt.getEventTitle()+ " Date:
"+evt.getStartDate());
}
}
}
活动类:
class Events{
private String eventId;
private String eventTitle;
private String startDate;
public Events(String eventId, String eventTitle, String startDate) {
super();
this.eventId = eventId;
this.eventTitle = eventTitle;
this.startDate = startDate;
}
public String getEventId() {
return eventId;
}
public void setEventId(String eventId) {
this.eventId = eventId;
}
public String getEventTitle() {
return eventTitle;
}
public void setEventTitle(String eventTitle) {
this.eventTitle = eventTitle;
}
public String getStartDate() {
return startDate;
}
public void setStartDate(String startDate) {
this.startDate = startDate;
}
}
答案 0 :(得分:1)
您可以使用HashMap<Date,List<Events>>
来实现此目标。
您可以获得日期,并且对于每个日期对象,您将获得List<Events>
个对象。获取此对象后(如果不存在则为NULL),您将能够添加/删除事件,然后使用put
方法再次存储它们。
希望有所帮助
修改强>
你的班级会宣布这样的事情:
HashMap<Date,List<Events>> my_events = new HashMap<Date,List<Events>>();
让我们举一些例子。
1 - 将事件添加到特定日期:
//suppose that you already have a date in which you want to add the new event
if(my_events.contains(given_date))
{
List<Events> aux = my_events.get(given_date);
aux.add(new_event);
my_events.put(given_date,aux);
}
else
{
List<Events> new_list = new ArrayList<Event>();
new_list.add(new_event);
my_events.put(given_date,new_list);
}
2 - 你想获得给定日期的所有事件:
return my_events.get(given_date); // this will return null if the given date (key) does not exists
答案 1 :(得分:0)
假设您按ID字段对项目进行分组,
// create a map which relates String-List of Event mapping
HashMap<String, List<Event>> listMap=new HashMap<String,List<Event>>();
// loop through the events
for(Events evt: mEvents){
if(!listMap.containsKey(evt.getID())){
listMap.put(evt.getID(), new ArrayList<Event>());
}
listMap.get(evt.getID()).add(evt);
}
// if you want to get a list of all events with the same ID,
Collection<Event> eventWithSpecificId=listMap.get("certain ID");