tree.java~2~

源程序（包括最初的版本

package tree;

/**
 * 2005.3.30 start
 */
public interface Tree {
    public boolean isEmpty(); //判空
   public Object root(); //求根
   //public void makeTree(Object root, Object left, Object right);
   //public Tree removeLeftSubtree();
   //public Tree removeRightSubtree();
   public void preOrder();
   public void postOrder();
}