dateformat.java

java源代码 请看看啊 提点宝贵的意见

     * @see java.util.Calendar#setLenient
     */
    public void setLenient(boolean lenient)
    {
        calendar.setLenient(lenient);
    }

    /**
     * Tell whether date/time parsing is to be lenient.
     */
    public boolean isLenient()
    {
        return calendar.isLenient();
    }

    /**
     * Overrides hashCode
     */
    public int hashCode() {
        return numberFormat.hashCode();
        // just enough fields for a reasonable distribution
    }

    /**
     * Overrides equals
     */
    public boolean equals(Object obj) {
        if (this == obj) return true;
        if (obj == null || getClass() != obj.getClass()) return false;
        DateFormat other = (DateFormat) obj;
        return (// calendar.equivalentTo(other.calendar) // THIS API DOESN'T EXIST YET!
                calendar.getFirstDayOfWeek() == other.calendar.getFirstDayOfWeek() &&
                calendar.getMinimalDaysInFirstWeek() == other.calendar.getMinimalDaysInFirstWeek() &&
                calendar.isLenient() == other.calendar.isLenient() &&
                calendar.getTimeZone().equals(other.calendar.getTimeZone()) &&
                numberFormat.equals(other.numberFormat));
    }

    /**
     * Overrides Cloneable
     */
    public Object clone()
    {
        DateFormat other = (DateFormat) super.clone();
        other.calendar = (Calendar) calendar.clone();
        other.numberFormat = (NumberFormat) numberFormat.clone();
        return other;
    }

    /**
     * Creates a DateFormat with the given time and/or date style in the given
     * locale.
     * @param timeStyle a value from 0 to 3 indicating the time format,
     * ignored if flags is 2
     * @param dateStyle a value from 0 to 3 indicating the time format,
     * ignored if flags is 1
     * @param flags either 1 for a time format, 2 for a date format,
     * or 3 for a date/time format
     * @param loc the locale for the format
     */
    private static DateFormat get(int timeStyle, int dateStyle,
                                  int flags, Locale loc) {
        if ((flags & 1) != 0) {
            if (timeStyle < 0 || timeStyle > 3) {
                throw new IllegalArgumentException("Illegal time style " + timeStyle);
            }
        } else {
            timeStyle = -1;
        }
        if ((flags & 2) != 0) {
            if (dateStyle < 0 || dateStyle > 3) {
                throw new IllegalArgumentException("Illegal date style " + dateStyle);
            }
        } else {
            dateStyle = -1;
        }
        try {
            return new SimpleDateFormat(timeStyle, dateStyle, loc);

        } catch (MissingResourceException e) {
            return new SimpleDateFormat("M/d/yy h:mm a");
        }
    }

    /**
     * Create a new date format.
     */
    protected DateFormat() {}

    /**
     * Defines constants that are used as attribute keys in the
     * <code>AttributedCharacterIterator</code> returned
     * from <code>DateFormat.formatToCharacterIterator</code> and as
     * field identifiers in <code>FieldPosition</code>.
     * <p>
     * The class also provides two methods to map
     * between its constants and the corresponding Calendar constants.
     *
     * @since 1.4
     * @see java.util.Calendar
     */
    public static class Field extends Format.Field {
        // table of all instances in this class, used by readResolve
        private static final Map instanceMap = new HashMap(18);
        // Maps from Calendar constant (such as Calendar.ERA) to Field
        // constant (such as Field.ERA).
        private static final Field[] calendarToFieldMapping =
                                             new Field[Calendar.FIELD_COUNT];

        /** Calendar field. */
        private int calendarField;

        /**
         * Returns the <code>Field</code> constant that corresponds to
         * the <code>Calendar</code> constant <code>calendarField</code>.
         * If there is no direct mapping between the <code>Calendar</code>
         * constant and a <code>Field</code>, null is returned.
         *
         * @throws IllegalArgumentException if <code>calendarField</code> is
         *         not the value of a <code>Calendar</code> field constant.
         * @param calendarField Calendar field constant
         * @return Field instance representing calendarField.
         * @see java.util.Calendar
         */
        public static Field ofCalendarField(int calendarField) {
            if (calendarField < 0 || calendarField >=
                        calendarToFieldMapping.length) {
                throw new IllegalArgumentException("Unknown Calendar constant "
                                                   + calendarField);
            }
            return calendarToFieldMapping[calendarField];
        }

        /**
         * Creates a Field with the specified name.
         * calendarField is used to identify the <code>Calendar</code>
         * field this attribute represents. Use -1 if this field does
         * not have a corresponding <code>Calendar</code> value.
         *
         * @param name Name of the attribute
         * @param calendarField Calendar constant
         */
        protected Field(String name, int calendarField) {
            super(name);
            this.calendarField = calendarField;
            if (this.getClass() == DateFormat.Field.class) {
                instanceMap.put(name, this);
                if (calendarField >= 0) {
                    // assert(calendarField < Calendar.FIELD_COUNT);
                    calendarToFieldMapping[calendarField] = this;
                }
            }
        }

        /**
         * Returns the <code>Calendar</code> field associated with this
         * attribute. For example, if this represents the hours field of
         * a <code>Calendar</code>, this would return
         * <code>Calendar.HOUR</code>. If there is no corresponding
         * <code>Calendar</code> constant, this will return -1.
         *
         * @return Calendar constant for this field
         * @see java.util.Calendar
         */
        public int getCalendarField() {
            return calendarField;
        }

        /**
         * Resolves instances being deserialized to the predefined constants.
         *
	 * @throws InvalidObjectException if the constant could not be
         *         resolved.
         * @return resolved DateFormat.Field constant
         */
        protected Object readResolve() throws InvalidObjectException {
            if (this.getClass() != DateFormat.Field.class) {
                throw new InvalidObjectException("subclass didn't correctly implement readResolve");
            }

            Object instance = instanceMap.get(getName());
            if (instance != null) {
                return instance;
            } else {
                throw new InvalidObjectException("unknown attribute name");
            }
        }

        //
        // The constants
        //

        /**
         * Constant identifying the era field.
         */
        public final static Field ERA = new Field("era", Calendar.ERA);

        /**
         * Constant identifying the year field.
         */
        public final static Field YEAR = new Field("year", Calendar.YEAR);

        /**
         * Constant identifying the month field.
         */
        public final static Field MONTH = new Field("month", Calendar.MONTH);

        /**
         * Constant identifying the day of month field.
         */
        public final static Field DAY_OF_MONTH = new
                            Field("day of month", Calendar.DAY_OF_MONTH);

        /**
         * Constant identifying the hour of day field, where the legal values
         * are 1 to 24.
         */
        public final static Field HOUR_OF_DAY1 = new Field("hour of day 1",-1);

        /**
         * Constant identifying the hour of day field, where the legal values
         * are 0 to 23.
         */
        public final static Field HOUR_OF_DAY0 = new
               Field("hour of day", Calendar.HOUR_OF_DAY);

        /**
         * Constant identifying the minute field.
         */
        public final static Field MINUTE =new Field("minute", Calendar.MINUTE);

        /**
         * Constant identifying the second field.
         */
        public final static Field SECOND =new Field("second", Calendar.SECOND);

        /**
         * Constant identifying the millisecond field.
         */
        public final static Field MILLISECOND = new
                Field("millisecond", Calendar.MILLISECOND);

        /**
         * Constant identifying the day of week field.
         */
        public final static Field DAY_OF_WEEK = new
                Field("day of week", Calendar.DAY_OF_WEEK);

        /**
         * Constant identifying the day of year field.
         */
        public final static Field DAY_OF_YEAR = new
                Field("day of year", Calendar.DAY_OF_YEAR);

        /**
         * Constant identifying the day of week field.
         */
        public final static Field DAY_OF_WEEK_IN_MONTH =
                     new Field("day of week in month",
                                            Calendar.DAY_OF_WEEK_IN_MONTH);

        /**
         * Constant identifying the week of year field.
         */
        public final static Field WEEK_OF_YEAR = new
              Field("week of year", Calendar.WEEK_OF_YEAR);

        /**
         * Constant identifying the week of month field.
         */
        public final static Field WEEK_OF_MONTH = new
            Field("week of month", Calendar.WEEK_OF_MONTH);

        /**
         * Constant identifying the time of day indicator
         * (e.g. "a.m." or "p.m.") field.
         */
        public final static Field AM_PM = new
                            Field("am pm", Calendar.AM_PM);

        /**
         * Constant identifying the hour field, where the legal values are
         * 1 to 12.
         */
        public final static Field HOUR1 = new Field("hour 1", -1);

        /**
         * Constant identifying the hour field, where the legal values are
         * 0 to 11.
         */
        public final static Field HOUR0 = new
                            Field("hour", Calendar.HOUR);

        /**
         * Constant identifying the time zone field.
         */
        public final static Field TIME_ZONE = new Field("time zone", -1);
    }
}