When does java.util.Date set value to cdate field?

Question

I debug in my code like this:

public static void main(String[] args) {
    Date date = new Date();
    System.out.println(date);
}

While seeing the source code, I find that it just set the value to fastTime.

public Date() {
    this(System.currentTimeMillis());
}

public Date(long date) {
    fastTime = date;
}

There is another field cdate field in java.util.Date, but how to set value to it?

/*
 * If cdate is null, then fastTime indicates the time in millis.
 * If cdate.isNormalized() is true, then fastTime and cdate are in
 * synch. Otherwise, fastTime is ignored, and cdate indicates the
 * time.
 */
private transient BaseCalendar.Date cdate;

[![debug pic]] [1]: https://i.stack.imgur.com/W2N7P.png

Answer 1

The implementation of PrintStream.println(Object) calls toString() for any object you pass into it.

Now if you look at the implementation of Date.toString() you see

    public String toString() {
        // "EEE MMM dd HH:mm:ss zzz yyyy";
        BaseCalendar.Date date = normalize();
        // format the contents of date
    }

You can then further look at Date.normalize() and find

    private final BaseCalendar.Date normalize() {
        if (cdate == null) {
            BaseCalendar cal = getCalendarSystem(fastTime);
            cdate = (BaseCalendar.Date) cal.getCalendarDate(fastTime,
                                                            TimeZone.getDefaultRef());
            return cdate;
        }
        // code to update cdate if it is already present
    }

Please note that a debugger that displays the current value of a variable Date date also uses the Date.toString() method. It might therefore be difficult to trace the code path in Date.normalize() with cdate == null