【发布时间】：2023-03-16 22:26:01
【问题描述】：
我正在尝试从哈希表中删除特定日期的数据，哈希表的类型为（字符串，向量）。最初我正在检查哈希表是否包含 usrDate，如果是，那么我需要删除所有数据 frm 哈希表仅用于usrDate 并添加新数据，即 listEvents。但不应删除来自哈希表的其他日期的包含。
listEvents.addElement(eventBean);//new data is here
for (int i = 0; i < listEvents.size();i++) {
EventData e = (EventData)listEvents.elementAt(i);
}
//checking if hashtable has given date
if (listUserEvents.containsKey(usrDate)) {
Vector info = (Vector)listUserEvents.get(usrDate);
info.addElement(eventBean);
listUserEvents.put(usrDate,info);
} else {
listUserEvents.put(usrDate,listEvents);
}
我只想将 listEvents 添加到给定日期的哈希表中，而不影响哈希表中包含其他日期数据的其他数据。
private Hashtable getEvents(String usrDate, String timezone) {
try {
listUserEvents = getUserInfo();
listEvents = new Vector();
Calendar calendarLocalEvent = Calendar.getInstance();
// fetches time zone
TimeZone timeZoneEvent = calendarLocalEvent.getTimeZone();
System.out.println("Time Zone first-->"
+ timeZoneEvent.getDefault());
if (timezone.equals(timeZoneEvent.getDefault())) {
;
} else {
TimeZone timeZoneChange = TimeZone.getTimeZone(timezone);
System.out.println("Time Zone change-->" +timeZoneChange);
Device.setTimeZone(timeZoneChange);
}
EventList eventList = (EventList) PIM.getInstance().openPIMList(
PIM.EVENT_LIST, PIM.READ_ONLY);
Enumeration events = eventList.items();
while (events.hasMoreElements()) {
System.out.println("in while");
Event event = (Event) events.nextElement();
if (eventList.isSupportedField(Event.START)
&& event.countValues(Event.START) > 0)
{
long start = event.getDate(Event.START, 0);
SimpleDateFormat sdf = new SimpleDateFormat(
"MMM dd,yyyy HH:mm");
SimpleDateFormat sdf_start = new SimpleDateFormat("HH:mm");
SimpleDateFormat sdf_start_min = new SimpleDateFormat("HH");
String dateString = sdf.formatLocal(start);
String timeString = sdf_start.formatLocal(start);
String hour = sdf_start_min.formatLocal(start);
SimpleDateFormat sdf1 = new SimpleDateFormat("MMM dd,yyyy");
String date = sdf1.formatLocal(start);
System.out.println("dates are :" + date +"user" + usrDate);
if (usrDate.equalsIgnoreCase(date)) {
System.out.println("dates are equal:" +date);
EventData eventBean = new EventData();
if (eventList.isSupportedField(Event.END)
&& event.countValues(Event.END) > 0) {
long end = event.getDate(Event.END, 0);
SimpleDateFormat sdform = new SimpleDateFormat(
"MMM dd, yyyy HH:mm");
SimpleDateFormat sdfTime = new SimpleDateFormat(
"HH:mm");
SimpleDateFormat sdfhr = new SimpleDateFormat("HH");
String dateString1 =sdform.formatLocal(end);
String timeString1 =sdfTime.formatLocal(end);
String hr = sdfhr.formatLocal(end);
eventBean.setStartHr(hour);
eventBean.setEndHr(hr);
eventBean.setStartTime(timeString);
eventBean.setEndTime(timeString1);
eventBean.setStartDate(dateString);
eventBean.setEndDate(dateString1);
// Dialog.alert("equal startdate" + dateString);
// Dialog.alert("equal end date"+ dateString1);
}
if (eventList.isSupportedField(Event.LOCATION)
&& event.countValues(Event.LOCATION) > 0) {
String location = event
.getString(Event.LOCATION, 0);
eventBean.setLocation(location);
// Dialog.alert("equal location"+ location);
}
if (eventList.isSupportedField(Event.SUMMARY)
&& event.countValues(Event.SUMMARY) > 0) {
String subject = event.getString(Event.SUMMARY, 0);
eventBean.setSummary(subject);
// Dialog.alert("equal subject" +subject);
}
eventBean.setUserDate(usrDate);
eventBean.setTimeZone(timezone);
listEvents.addElement(eventBean);
System.out.println("the size bf hashis"
+ listEvents.size());
for (int i = 0; i < listEvents.size();i++) {
EventData e = (EventData)listEvents.elementAt(i);
System.out.println("so thesummary is ::"
+ e.getSummary());
}
// for(int i=0;i<listUserEvents.size();i++){
if (listUserEvents.containsKey(usrDate)) {
// listUserEvents.remove(usrDate);
Vector info = (Vector)listUserEvents.get(usrDate);
System.out.println("the size in getEvents is"
+ info.size());
if(info.contains(usrDate)){
System.out.println("in info");
}
info.addElement(eventBean);
System.out.println("vector size info is"
+ info.size());
listUserEvents.put(usrDate,info);
} else {
System.out.println("in else of getevent" +listEvents.size());
listUserEvents.put(usrDate,listEvents);
}
// }
} else {
// Dialog.alert("not equal");
}
}
}
Device.setTimeZone(timeZoneEvent);
Calendar calendarLocalLastEvent = Calendar.getInstance();
// fetches time zone
TimeZone timeZoneEventLast =calendarLocalLastEvent.getTimeZone();
System.out.println("Time Zone last-->"
+ timeZoneEventLast.getDefault());
} catch (PIMException e) {
// //Dialog.alert(e.getMessage());
}
System.out.println("size in hashtable " + listUserEvents.size());
return listUserEvents;
}
【问题讨论】：
-
好吧，要么你的哈希表键必须是日期，要么你需要遍历所有的哈希表条目。如果要删除条目，请使用
remove(key)删除它。 -
你的问题不清楚。您在哪里遇到问题？
-
@HotLicks 我使用了 remove(key) 但它确实有效，请您修改 sn-p 并用示例显示
-
@sheetal_roswal：当您在哈希表上调用
containsKey(key)时，它是否返回false？还是remove(key)返回null？ -
@KuldeepJain 我正面临哈希表问题，如果它有 usrDate，我需要检查哈希表，如果是，则从哈希表中删除该日期的数据并在该日期向其中添加新内容