modificato arraysequence in fake e aggiunti una nuova versione. fidato alcuni metodi che restituivano void invece di position. sono necessari ulteriori test

sequence/utility/ArrayPosition.java

@@ -0,0 +1,51 @@
+package sequence.utility;
+
+import exceptions.InvalidPositionException;
+import position.Position;
+
+
+/**
+ * A simple node class for a doubly-linked list.  Each DNode has a
+ * reference to a stored element, a previous node, and a next node.
+ * 
+ * @author Roberto Tamassia
+ */
+//Copyright (c) 2003 Brown University, Providence, RI
+//Additional modifications and methods by xgiovio
+
+// used on ArraySequence
+
+
+public class ArrayPosition<E> implements Position<E> {
+  private E element = null;
+  private int index = -1;
+
+
+  public ArrayPosition(E elem, int in_idex) {
+
+    element = elem;
+    index = in_idex;
+  }
+  public ArrayPosition(E elem) {
+
+        element = elem;
+  }
+
+  public E element() throws InvalidPositionException {
+    if (index == -1)
+      throw new InvalidPositionException("Position is not in a list!");
+    return element;
+  }
+
+
+  public void setElement(E newElement) { element = newElement; }
+
+    public int getIndex() {
+        return index;
+    }
+
+    public void setIndex(int index) {
+        this.index = index;
+    }
+}
+