diff -r 000000000000 -r fb9019fb1bf7 src/net/fortuna/ical4j/model/property/DateProperty.java
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/net/fortuna/ical4j/model/property/DateProperty.java	Tue Feb 10 18:12:00 2015 +0100
@@ -0,0 +1,288 @@
+/**
+ * Copyright (c) 2012, Ben Fortuna
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ *  o Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ *
+ *  o Redistributions in binary form must reproduce the above copyright
+ * notice, this list of conditions and the following disclaimer in the
+ * documentation and/or other materials provided with the distribution.
+ *
+ *  o Neither the name of Ben Fortuna nor the names of any other contributors
+ * may be used to endorse or promote products derived from this software
+ * without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
+ * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
+ * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+ * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
+ * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
+ * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
+ * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+ * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+package net.fortuna.ical4j.model.property;
+
+import java.io.IOException;
+import java.net.URISyntaxException;
+import java.text.ParseException;
+
+import net.fortuna.ical4j.model.Date;
+import net.fortuna.ical4j.model.DateTime;
+import net.fortuna.ical4j.model.Parameter;
+import net.fortuna.ical4j.model.ParameterList;
+import net.fortuna.ical4j.model.Property;
+import net.fortuna.ical4j.model.PropertyFactory;
+import net.fortuna.ical4j.model.TimeZone;
+import net.fortuna.ical4j.model.ValidationException;
+import net.fortuna.ical4j.model.parameter.TzId;
+import net.fortuna.ical4j.model.parameter.Value;
+import net.fortuna.ical4j.util.ParameterValidator;
+import net.fortuna.ical4j.util.Strings;
+
+/**
+ * $Id$
+ *
+ * Created on 9/07/2005
+ *
+ * Base class for properties with a DATE or DATE-TIME value. Note that some sub-classes may only allow either a DATE or
+ * a DATE-TIME value, for which additional rules/validation should be specified.
+ * @author Ben Fortuna
+ */
+public abstract class DateProperty extends Property {
+
+    private static final long serialVersionUID = 3160883132732961321L;
+    
+    private Date date;
+
+    private TimeZone timeZone;
+
+    /**
+     * @param name the property name
+     * @param parameters a list of initial parameters
+     */
+    public DateProperty(final String name, final ParameterList parameters, PropertyFactory factory) {
+        super(name, parameters, factory);
+    }
+
+    /**
+     * @param name the property name
+     */
+    public DateProperty(final String name, PropertyFactory factory) {
+        super(name, factory);
+    }
+
+    /**
+     * Creates a new instance of the named property with an initial timezone.
+     * @param name property name
+     * @param timezone initial timezone
+     */
+    public DateProperty(final String name, TimeZone timezone, PropertyFactory factory) {
+        super(name, factory);
+        updateTimeZone(timezone);
+    }
+
+    /**
+     * @return Returns the date.
+     */
+    public final Date getDate() {
+        return date;
+    }
+
+    /**
+     * Sets the date value of this property. The timezone and value of this
+     * instance will also be updated accordingly.
+     * @param date The date to set.
+     */
+    public final void setDate(final Date date) {
+        this.date = date;
+        if (date instanceof DateTime) {
+            if (Value.DATE.equals(getParameter(Parameter.VALUE))) {
+                getParameters().replace(Value.DATE_TIME);
+            }
+            updateTimeZone(((DateTime) date).getTimeZone());
+        }
+        else {
+            if (date != null) {
+                getParameters().replace(Value.DATE);
+            }
+            /*
+            else {
+                getParameters().removeAll(Parameter.VALUE);
+            }
+            */
+            // ensure timezone is null for VALUE=DATE or null properties..
+            updateTimeZone(null);
+        }
+    }
+
+    /**
+     * Default setValue() implementation. Allows for either DATE or DATE-TIME values.
+     * 
+     * @param value a string representation of a DATE or DATE-TIME value
+     * @throws ParseException where the specified value is not a valid DATE or DATE-TIME
+     * representation
+     */
+    public void setValue(final String value) throws ParseException {
+        // value can be either a date-time or a date..
+        if (Value.DATE.equals(getParameter(Parameter.VALUE))) {
+            // ensure timezone is null for VALUE=DATE properties..
+            updateTimeZone(null);
+            this.date = new Date(value);
+        }
+        else {
+            this.date = new DateTime(value, timeZone);
+        }
+    }
+
+    /**
+     * {@inheritDoc}
+     */
+    public String getValue() {
+        return Strings.valueOf(getDate());
+    }
+
+    /**
+     * Publically available method to update the current timezone.
+     * @param timezone a timezone instance
+     */
+    public void setTimeZone(final TimeZone timezone) {
+        updateTimeZone(timezone);
+    }
+    
+    /**
+     * @return the timezone
+     */
+    public final TimeZone getTimeZone() {
+        return timeZone;
+    }
+    
+    /**
+     * {@inheritDoc}
+     */
+    public int hashCode() {
+        return getDate().hashCode();
+    }
+
+    /**
+     * Updates the timezone associated with the property's value. If the specified timezone is equivalent to UTC any
+     * existing TZID parameters will be removed. Note that this method is only applicable where the current date is an
+     * instance of <code>DateTime</code>. For all other cases an <code>UnsupportedOperationException</code> will be
+     * thrown.
+     * @param vTimeZone
+     */
+    private void updateTimeZone(final TimeZone timezone) {
+        this.timeZone = timezone;
+        if (timezone != null) {
+            if (getDate() != null && !(getDate() instanceof DateTime)) {
+                throw new UnsupportedOperationException(
+                        "TimeZone is not applicable to current value");
+            }
+            if (getDate() != null) {
+                ((DateTime) getDate()).setTimeZone(timezone);
+            }
+
+            getParameters().replace(new TzId(timezone.getID()));
+        }
+        else {
+            // use setUtc() to reset timezone..
+            setUtc(isUtc());
+        }
+    }
+
+    /**
+     * Resets the VTIMEZONE associated with the property. If utc is true, any TZID parameters are removed and the Java
+     * timezone is updated to UTC time. If utc is false, TZID parameters are removed and the Java timezone is set to the
+     * default timezone (i.e. represents a "floating" local time)
+     * @param utc a UTC value
+     */
+    public final void setUtc(final boolean utc) {
+        if (getDate() != null && (getDate() instanceof DateTime)) {
+            ((DateTime) getDate()).setUtc(utc);
+        }
+        getParameters().remove(getParameter(Parameter.TZID));
+    }
+
+    /**
+     * Indicates whether the current date value is specified in UTC time.
+     * @return true if the property is in UTC time, otherwise false
+     */
+    public final boolean isUtc() {
+        if (getDate() instanceof DateTime) {
+            return ((DateTime) getDate()).isUtc();
+        }
+        return false;
+    }
+
+    /**
+     * {@inheritDoc}
+     */
+    public void validate() throws ValidationException {
+
+        ParameterValidator.getInstance().assertOneOrLess(Parameter.VALUE,
+                getParameters());
+
+        if (isUtc()) {
+            ParameterValidator.getInstance().assertNone(Parameter.TZID,
+                    getParameters());
+        }
+        else {
+            ParameterValidator.getInstance().assertOneOrLess(Parameter.TZID,
+                    getParameters());
+        }
+
+        final Value value = (Value) getParameter(Parameter.VALUE);
+
+        if (getDate() instanceof DateTime) {
+
+            if (value != null && !Value.DATE_TIME.equals(value)) {
+                throw new ValidationException("VALUE parameter [" + value
+                        + "] is invalid for DATE-TIME instance");
+            }
+
+            final DateTime dateTime = (DateTime) date;
+
+            // ensure tzid matches date-time timezone..
+            final Parameter tzId = getParameter(Parameter.TZID);
+            if (dateTime.getTimeZone() != null
+                    && (tzId == null || !tzId.getValue().equals(
+                            dateTime.getTimeZone().getID()))) {
+
+                throw new ValidationException("TZID parameter [" + tzId
+                        + "] does not match the timezone ["
+                        + dateTime.getTimeZone().getID() + "]");
+            }
+        }
+        else if (getDate() != null) {
+
+            if (value == null) {
+                throw new ValidationException("VALUE parameter [" + Value.DATE
+                        + "] must be specified for DATE instance");
+            }
+            else if (!Value.DATE.equals(value)) {
+                throw new ValidationException("VALUE parameter [" + value
+                        + "] is invalid for DATE instance");
+            }
+        }
+    }
+    
+    /**
+     * {@inheritDoc}
+     */
+    public Property copy() throws IOException, URISyntaxException, ParseException {
+        final Property copy = super.copy();
+        
+       ((DateProperty) copy).timeZone = timeZone;
+       ((DateProperty) copy).setValue(getValue());
+       
+        return copy;
+    }
+}