wrong time shown in Datefield related to TimeZones in Blackberry

I have a problem relating to a countdown based on a DateField.

App - set a DateField including a default Value (10 minutes) - get the value of the field, start a thread and reduce the 开发者_高级运维value every second - show the new value every second on a screen

Problem If my simulator/device is GMT everything works fine. But if I change the DateField and result screen shows a wrong value.

Here the Datefield is and default value is set

long time = 1000*60*DEFAULT_PARKING;        
parkingTimePicker = new DateField("",time, DateField.TIME);
TimeZone zone = TimeZone.getTimeZone("GMT");
parkingTimePicker.setTimeZone(zone);

Afterwards the remaining seconds are reduced every second.

Here the remaining time in the thread is translated from seconds back to hh:mm:ss

public void showTimeLeft()
{             
    private long timeLeft; //time left in Seconds
    private SimpleDateFormat sdf = new SimpleDateFormat("HH:mm:ss");
    private Date resultdate;
     resultdate = new Date(timeLeft*1000);
     mainScreen.setRemainingTimeLabel(sdf.format(resultdate));
}

Here the method which shows the value on the mainscreen

public void setRemainingTimeLabel(String text)
{       
    remainingTimeLabel.setText(text);
    add(new LabelField(System.currentTimeMillis()+""));
    add(new LabelField(text));  
}

I am not sure where I made the mistake but I am pretty sure it is related to the Timezone. How can I make sure my app works in different timezones?

I believe you misused DateField. It is designed to manipulate with timestamps (which include the date itself + time within the date). Yes, DateField may show only time part of the timestamp, however its constructor expects a long representing a full timestamp (both date + time parts). So by passing long time = 1000*60*DEFAULT_PARKING what date do you pass? I'd recommend to use something like this:

int millisSinceMidnight = 1000 * 60 * DEFAULT_PARKING;
// Retrieves date relative to midnight on current day.
Calendar dateCal = DateTimeUtilities.getDate(millisSinceMidnight);
long time = dateCal.getTime().getTime();
parkingTimePicker = new DateField("", time, DateField.TIME);

It is unclear how do you calculate timeLeft. Probably post the code if the issue is still present after reading/using this post.

I also believe SimpleDateFormat formats time using the current device timezone. So your code only works if device timezone is GMT. To workaround this you should remove this:

TimeZone zone = TimeZone.getTimeZone("GMT");
parkingTimePicker.setTimeZone(zone);

so both picker and formatter work in the same timezone (current on the device).