Matrixable.java

   public interface Matrixable<anyType> // implements Cloneable
   {
      public anyType get(int r, int c);				//returns the element at row r, col c
      public anyType set(int r, int c, anyType x);	//changes element at (r,c), returns old value
      public void add(int r, int c, anyType x);	   //adds obj at row r, col c
      public anyType remove(int r, int c);
      public int size();			//returns # actual elements stored
      public int numRows();		//returns # rows set in constructor
      public int numColumns();	//returns # cols set in constructor
      
      public Object[][] toArray();				//returns equivalent structure in 2-D array form
      public boolean contains(anyType x);		//true if x exists in list
      public int[] getLocation(anyType x);	//returns location [r,c] of where x exists in list, null otherwise
      public boolean isEmpty();					//returns true if there are no actual elements stored
      public void clear();							//clears all elements out of the list
		public void setBlank(char blank);		//allows the client to set the character that a blank spot in the array is
															//represented by in String toString()
      public Matrixable<anyType> clone();  //clone a Matrixable
   }