如何检查时间是否重叠？

Question

我创建了一个事件。现在我想检查它们是否重叠。我在数据库中以日期格式存储了开始时间和结束时间。

现在我想检查事件的时间是否重叠。为此，我想获取所有事件start Time和endTime，从日期检索小时和分钟，然后将小时和分钟与当前小时和分钟进行比较。

日期格式如下：df=新的SimpleDateFormat（“E-MMM-dd-HH:mm:ss-zz-yyyy”）；

我第一次尝试通过查询比较两个日期，但没有很好的帮助。如果当时事件不存在，那么有时它也会返回true。

我的第一次尝试是这样的：

public int returnCount(String startTime, String endTime, String day)
{
    String selectQuery = "SELECT COUNT(*) FROM " + TABLE + " WHERE " + KEY_DAY_OF_WEEK + " = '" + day + "'" + " AND "

            + "(" + KEY_FROM_DATE + " <= '" + startTime
            + "' AND '" + startTime + "' <= " + KEY_TO_DATE + ") OR "

            + " (" + KEY_FROM_DATE + " <= '" + endTime
            + "' AND '" + endTime + "' <= " + KEY_TO_DATE + ") OR "

            + " (" + KEY_FROM_DATE + " <= '" + startTime
            + "' AND '" + endTime + "' <= " + KEY_TO_DATE + ") OR "

            + " (" + KEY_FROM_DATE + " <= '" + endTime
            + "' AND '" + startTime + "' <= " + KEY_FROM_DATE + ") OR "

            + " (" + KEY_TO_DATE + " <= '" + startTime
            + "' AND '" + endTime + "' <= " + KEY_TO_DATE + ") OR "

            + " ('" + startTime + "' < " + KEY_FROM_DATE
            + " AND " + KEY_TO_DATE + " < '" + endTime + "')";

    SQLiteDatabase db = this.getWritableDatabase();
    Cursor mCount= db.rawQuery(selectQuery,null);

    if (mCount.moveToFirst()) {
        do {
            EventData event = new EventData();
            count = mCount.getInt(0);
        } while (mCount.moveToNext());
    }

    Log.d("query",selectQuery);

    Log.d("count",String.valueOf(count));
    mCount.close();

    return count;

}

所以现在我想做一个改变，比较小时和分钟。为此，我尝试将小时和分钟转换为字符串，然后进行比较，但这并没有什么帮助。

 public void checkOverlappingEvents()
{

    List<EventData> checkOverlappingEvents = new ArrayList<>();

    EventTableHelper eventTableHelper = new EventTableHelper(AddEventActivity.this);


    checkOverlappingEvents = eventTableHelper.getAllEvents("Mon");


    for (EventData e : checkOverlappingEvents)
    {

        df = new SimpleDateFormat("E MMM dd HH:mm:ss zzzz yyyy");

        Date checkFromDate = new Date();
        Date checkToDate = new Date();


        try {

            checkFromDate = df.parse(e.getFromDate());
            checkToDate = df.parse(e.getToDate());

        } catch (ParseException ex) {

        }


        int startHours = datefrom.getHours();
        int endHours = dateto.getMinutes();

        String startTime = checkFromDate.getHours() + ":" + checkFromDate.getMinutes();
        String endTime = checkToDate.getHours() + ":" + checkToDate.getMinutes();

        String startDate = datefrom.getHours() + ":" + datefrom.getMinutes();
        String endDate = dateto.getHours() + ":" + dateto.getMinutes();

        if(startTime.equals(startDate) && endTime.equals(endDate))
        {
            overlapEvents = true;
        }

    }

}

getAllEvents查询：

 public List<EventData> getAllEvents(String day) {
    List<EventData> conList = new ArrayList<EventData>();

    String selectQuery = "SELECT  * FROM " + TABLE + " WHERE " + KEY_DAY_OF_WEEK + " = '" + day + "'";

    SQLiteDatabase db = this.getWritableDatabase();
    Cursor cursor = db.rawQuery(selectQuery, null);

    if (cursor.moveToFirst()) {
        do {

            EventData event = new EventData();

            event.setId(Integer.parseInt(cursor.getString(0)));
            event.setTitle(cursor.getString(1));
            event.setFromDate(cursor.getString(2));
            event.setToDate(cursor.getString(3));
            event.setDayOfWeek(cursor.getString(4));
            event.setLocation(cursor.getString(5));
            event.setNotificationTime(cursor.getString(6));
            event.setTableId(Integer.parseInt(cursor.getString(7)));
            event.setNotificationId(Integer.parseInt(cursor.getString(8)));
            event.setNotification(cursor.getString(9));



            conList.add(event);
        } while (cursor.moveToNext());
    }

    return conList;
}

编辑：

public void checkOverlappingEvents()
{

    List<EventData> checkOverlappingEvents = new ArrayList<>();

    EventTableHelper eventTableHelper = new EventTableHelper(AddEventActivity.this);


    checkOverlappingEvents = eventTableHelper.getAllEvents("Mon");


    for (EventData e : checkOverlappingEvents)
    {

        df = new SimpleDateFormat("E MMM dd HH:mm:ss zzzz yyyy");

        Date checkFromDate = new Date();
        Date checkToDate = new Date();


        try {

            checkFromDate = df.parse(e.getFromDate());
            checkToDate = df.parse(e.getToDate());

        } catch (ParseException ex) {

        }

checkToDate.getMinutes（）;

        if(datefrom.compareTo(checkToDate) == checkFromDate.compareTo(dateto))
        {
            overlapEvents = true;
        }

    }

}

我这样做是为了让它能很好地添加新事件。检查其他日期是否重叠，但我也想更新事件。

如果我使用相同的函数并且只更改现有事件的结束时间，那么当开始时间相同时，它总是显示事件存在。如何在更新事件时进行比较？

有人可以帮助我如何将小时和分钟与当前小时和分钟进行比较？

Answer 1

我建议您将字符串< code>startTime和< code>endTime转换为< code>Date对象，并使用< code > Date 1 . compare to(Date 2)，如果< code>date2发生在< code >之后，则返回< code>1，如果在< code >之前，则返回< code>0同时。所以你会有这样的东西:

if(start1.compareTo(start2) != end1.compareTo(start2)) /*overlaps*/;  

当你想象它的时候，你可以看到它是如何工作的:

start1--------start2------end1--------end2  → will return true
start1--------end1------start2--------end2  → will return false  

请注意，这计算了一个范围恰好在另一个范围重叠时开始的情况。如果您不希望这样，您应该处理开始与另一端相同的情况

Answer 2

我会使用< code>Date对象

Date startDate1 = ...
Date startDate2 = ...
Date endDate1 = ...
Date endDate2 = ...

boolean overlapping = datesOverlap(startDate1, endDate1, startDate2, endDate2);

private boolean datesOverlap(Date startDate1, endDate1, startDate2, endDate2){
    return startDate1.before(endDate2) && startDate2.before(endDate1);
}