Define an order relationship for TaskDates

FEA: ItEr60S19TimeUnitDataType

navalplanner-business/src/main/java/org/navalplanner/business/workingday/TaskDate.java

@@ -19,6 +19,8 @@
  */
 package org.navalplanner.business.workingday;
 
+import java.util.Arrays;
+import java.util.Collections;
 import java.util.Date;
 
 import org.apache.commons.lang.Validate;
@@ -31,7 +33,17 @@ import org.joda.time.LocalDate;
  * @author Óscar González Fernández
  *
  */
-public class TaskDate {
+public class TaskDate implements Comparable<TaskDate> {
+
+    public static TaskDate min(TaskDate... dates) {
+        Validate.noNullElements(dates);
+        return Collections.min(Arrays.asList(dates));
+    }
+
+    public static TaskDate max(TaskDate... dates) {
+        Validate.noNullElements(dates);
+        return Collections.max(Arrays.asList(dates));
+    }
 
     public static TaskDate create(LocalDate date, EffortDuration effortDuration) {
         return new TaskDate(date, effortDuration);
@@ -92,4 +104,13 @@ public class TaskDate {
         return this.date.toDateTimeAtStartOfDay();
     }
 
+    @Override
+    public int compareTo(TaskDate other) {
+        int result = date.compareTo(other.date);
+        if (result == 0) {
+            result = effortDuration.compareTo(other.effortDuration);
+        }
+        return result;
+    }
+
 }

navalplanner-business/src/test/java/org/navalplanner/business/test/workingday/TaskDateTest.java

@@ -82,4 +82,21 @@ public class TaskDateTest {
                 .toDateTimeAtStartOfDay();
         assertThat(dateTime, equalTo(today.toDateTimeAtStartOfDay()));
     }
+
+    @Test
+    public void implementsComparable() {
+        assertTrue(Comparable.class.isAssignableFrom(TaskDate.class));
+        assertTrue(TaskDate.create(today, halfHour).compareTo(
+                TaskDate.create(today, oneHour)) < 0);
+        assertTrue(TaskDate.create(today, oneHour).compareTo(
+                TaskDate.create(tomorrow, halfHour)) < 0);
+    }
+
+    @Test
+    public void hasMaxAndMinMethods() {
+        TaskDate a = TaskDate.create(today, halfHour);
+        TaskDate b = TaskDate.create(today, oneHour);
+        assertThat(TaskDate.min(a, b), equalTo(a));
+        assertThat(TaskDate.max(a, b), equalTo(b));
+    }
 }