diff --git a/src/main/java/edu/nps/moves/dis7/EntityID.java b/src/main/java/edu/nps/moves/dis7/EntityID.java
index 7ccbe33..06aef30 100644
--- a/src/main/java/edu/nps/moves/dis7/EntityID.java
+++ b/src/main/java/edu/nps/moves/dis7/EntityID.java
@@ -1,6 +1,7 @@
 package edu.nps.moves.dis7;
 
 import java.io.*;
+import java.util.Objects;
 
 
 /**
@@ -165,4 +166,10 @@ public boolean equalsImpl(Object obj)
 
     return ivarsEqual;
  }
+
+    @Override
+    public int hashCode()
+    {
+        return Objects.hash(siteID, applicationID, entityID);
+    }
 } // end of class
diff --git a/src/test/java/edu/nps/moves/dis7/EntityIDTest.java b/src/test/java/edu/nps/moves/dis7/EntityIDTest.java
new file mode 100644
index 0000000..e5c0285
--- /dev/null
+++ b/src/test/java/edu/nps/moves/dis7/EntityIDTest.java
@@ -0,0 +1,90 @@
+package edu.nps.moves.dis7;
+
+
+import org.junit.Before;
+import org.junit.Test;
+
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.HashMap;
+import java.util.List;
+import java.util.Map;
+import java.util.stream.Collectors;
+
+import static org.junit.Assert.*;
+
+
+public class EntityIDTest
+{
+    EntityID id1;
+    EntityID id2;
+    EntityID id3;
+    EntityID id4;
+
+    @Before
+    public void setUp()
+        throws Exception
+    {
+        id1 = new EntityID();
+        id1.setEntityID(1);
+        id1.setApplicationID(2);
+        id1.setSiteID(3);
+        // id1 and id2 have the same entityID, applicationID, siteID
+        id2 = new EntityID();
+        id2.setEntityID(1);
+        id2.setApplicationID(2);
+        id2.setSiteID(3);
+
+        id3 = new EntityID();
+        id3.setEntityID(1);
+        id3.setApplicationID(2);
+        id3.setSiteID(4);   // different site id
+
+        id4 = new EntityID();
+        id4.setEntityID(1);
+        id4.setApplicationID(2);
+        id4.setSiteID(5);   // different site id
+    }
+
+    @Test
+    public void EntityIDEquals_test()
+    {
+        assertEquals(id1, id2);
+        assertNotEquals(id1, id3);
+        assertNotEquals(id3, id4);
+    }
+
+    @Test
+    public void EntityID_Lists_tests()
+    {
+        List<EntityID> list = Arrays.asList(id1, id2, id3, id4);
+
+        assertTrue(list.contains(id1));
+        assertEquals(id2, list.get(list.indexOf(id2)));
+
+        List<EntityID> collect = list.stream().filter(e -> e.getSiteID() == 3).collect(Collectors.toList());
+        assertEquals(2, collect.size());
+        assertTrue(collect.contains(id1));
+    }
+
+    @Test
+    public void EntityID_Map_tests()
+    {
+        Map<EntityID, String> map = new HashMap<>();
+        map.put(id1, "id1");
+        map.put(id2, "id2");    // id1 and id2 have the same entity, application, and site id. Therefore "id2" replaces "id1"
+        map.put(id3, "id3");
+        map.put(id4, "id4");
+
+        assertEquals(3, map.size());
+        assertEquals("id3", map.get(id3));
+        assertTrue(map.containsKey(id2));
+        assertTrue(map.containsValue("id3"));
+
+        map.forEach((entityID, s) -> {
+            if (entityID.equals(id4)) {
+                assertTrue(true);
+            }
+        });
+    }
+}
\ No newline at end of file