计算当前和未来时间之间的时差

Question

I want to calculate time difference in milliseconds from current time of a day(11 am , 1 october,2012) and time at midnight for the same day (11 pm 59 m 59s , 1 october , 2012.

I have tried this

    Calendar cal = Calendar.getInstance();
    cal.add(Calendar.SECOND, 59);
    cal.add(Calendar.HOUR, 23);
    cal.add(Calendar.MINUTE, 59);
        cal.getTime().getTime() - today.getTime();

here today is the current date.

But when i print long values of cal and today , the time difference if of 86400 approx one day.

Answer 1

Use cal.set() instead of cal.add()

Calendar cal = Calendar.getInstance();
cal.set(Calendar.SECOND, 59);
cal.set(Calendar.HOUR, 23);
cal.set(Calendar.MINUTE, 59);

long diff = cal.getTime().getTime() - today.getTime();

Answer 2

You can set your date to newly created Calendar instance.. And then compare it with current instance using getTimeInMillis()

Calendar cal = Calendar.getInstance();
cal.set(Calendar.HOUR, 23);
cal.set(Calendar.MINUTE, 59);
cal.set(Calendar.SECOND, 59);
cal.set(Calendar.DATE, 1);
cal.set(Calendar.MONTH, 9);
cal.set(Calendar.YEAR, 2012);

long difference = cal.getTimeInMillis() - Calendar.getInstance().getTimeInMillis();