// The next class is used for expression trees.  These have two kinds of
// nodes, operators at the internal nodes (which always have two children)
// and leaves which are variables.  Later I will define two classes to
// represent these kinds of nodes but this class still has Object as the
// node type.

class ExpTree extends BinTree {

  public ExpTree(Object root){super(root);}//I used the superclass code to
                                           // initialize this
  // The next method should also use the super keyword
  public ExpTree(Object root, ExpTree l, ExpTree r){
    super(root,l,r);
  }
  
  //A silly test of ExpTree,  modify this to perform slightly better tests
  public static void main(String[] args){
    ExpTree e = new ExpTree(new Character('+'));
    e.SetLeft(new ExpTree(new Integer(2)));
    e.SetRight(new ExpTree(new Integer(3)));
    e.inorder();
  }
  //Remember there will be a class file called ExpTree.class generated
  //along with lots of other class files.  You can test each class (if you
  //have written a main method for it by saying "java classfilename.class"
}//end ExpTree