1   /* Copyright 2002-2021 CS GROUP
2    * Licensed to CS GROUP (CS) under one or more
3    * contributor license agreements.  See the NOTICE file distributed with
4    * this work for additional information regarding copyright ownership.
5    * CS licenses this file to You under the Apache License, Version 2.0
6    * (the "License"); you may not use this file except in compliance with
7    * the License.  You may obtain a copy of the License at
8    *
9    *   http://www.apache.org/licenses/LICENSE-2.0
10   *
11   * Unless required by applicable law or agreed to in writing, software
12   * distributed under the License is distributed on an "AS IS" BASIS,
13   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14   * See the License for the specific language governing permissions and
15   * limitations under the License.
16   */
17  package org.orekit.time;
18  
19  import org.hipparchus.CalculusFieldElement;
20  
21  /** This interface represents objects that have a {@link AbsoluteDate}
22   * date attached to them.
23   * <p>Classes implementing this interface can be stored chronologically
24   * in sorted sets using {@link ChronologicalComparator} as the
25   * underlying comparator. An example using for {@link org.orekit.orbits.Orbit
26   * Orbit} instances is given here:</p>
27   * <pre>
28   *     SortedSet&lt;Orbit&gt; sortedOrbits =
29   *         new TreeSet&lt;Orbit&gt;(new ChronologicalComparator());
30   *     sortedOrbits.add(orbit1);
31   *     sortedOrbits.add(orbit2);
32   *     ...
33   * </pre>
34   * <p>This interface is also the base interface used to {@link
35   * org.orekit.utils.TimeStampedCache cache} series of time-dependent
36   * objects for interpolation in a thread-safe manner.</p>
37   * @see AbsoluteDate
38   * @see ChronologicalComparator
39   * @see org.orekit.utils.TimeStampedCache
40   * @author Luc Maisonobe
41   */
42  public interface FieldTimeStamped<T extends CalculusFieldElement<T>> {
43  
44      /** Get the date.
45       * @return date attached to the object
46       */
47      FieldAbsoluteDate<T> getDate();
48  
49  }