Implementato NodeSequence e aggiunto alcuni costruttori alle eccezioni

sequence/Sequence.java

@@ -0,0 +1,24 @@
+package sequence;
+
+import arraylist.IndexList;
+import position.Position;
+import position.PositionList;
+import exceptions.*;
+
+/**
+ * Created with MONSTER.
+ * User: xgiovio
+ * Date: 30/03/2014
+ * Time: 14:31
+ */
+public interface Sequence<E> extends PositionList<E>, IndexList<E> {
+    public E getFirst() throws EmptySequenceException;
+    public E getLast()  throws  EmptySequenceException;
+    public E removeFirst() throws  EmptySequenceException;
+    public E removeLast() throws EmptySequenceException;
+
+    public Position<E> atIndex(  int  index)  throws  BoundaryViolationException;
+    public int  indexOf(Position <E> position) throws InvalidPositionException;
+
+
+}