Data Structures, Algorithms, & Applications in Java
Chapter 8, Exercise 43

The code to make a clone is given below. The code clones each matrix term by copying the data members of the matrix term. An iterator is used to retrieve the matrix terms from the ExtendedArrayList they are stored in. 
public class SparseMatrixAsExtendedArrayListWithClone
              extends SparseMatrixAsExtendedArrayList
              implements CloneableObject
{
   // constructors
   public SparseMatrixAsExtendedArrayListWithClone
                (int theRows, int theColumns,
                 int estimatedMaxSize, Object theZero)
      {super(theRows, theColumns, estimatedMaxSize, theZero);}

   /** use a default estimated maximum size of 1 */
   public SparseMatrixAsExtendedArrayListWithClone
                (int theRows, int theColumns,
                 Object theZero)
      {this(theRows, theColumns, 1, theZero);}
   
   /** defaults are rows = cols = estimatedMaxSize = 1 */
   public SparseMatrixAsExtendedArrayListWithClone(Object theZero)
      {this(1, 1, 1, theZero);}

   /** read in a sparse matrix into this from the given input stream */
   public void read(Object theZero, MyInputStream stream)
   {
      SparseMatrixAsExtendedArrayList x = input(theZero, stream);
      // transfer to SparseMatrixAsExtendedArrayListWithClone
      rows = x.rows;
      cols = x.cols;
      zero = x.zero;
      terms = x.terms;
   }

   /** return a clone of this */
   public Object clone()
   {
      // define the clone w
      SparseMatrixAsExtendedArrayListWithClone w =
            new SparseMatrixAsExtendedArrayListWithClone
                      (rows, cols, terms.size(), zero);

      // set the matrix elements by using a ExtendedArrayList enumerator
      Iterator it = terms.iterator();
      int cw = 0;    // cursor into w
      while (it.hasNext())
      {
         MatrixTerm nextTerm = (MatrixTerm) it.next();
         MatrixTerm clonedTerm = new MatrixTerm(nextTerm.row, nextTerm.col,
                    ((CloneableObject) nextTerm.value).clone());
         w.terms.add(cw++, clonedTerm);
      }

      return w;
   }
}