Data Structures and Algorithms in Java[1].pdf - Fulvio Frisone

There are also a number of generic methods a tree should probably support that are
not necessarily related to its tree structure, including the following:
size():
return the number of nodes in the tree.
isEmpty():
Test whether the tree has any nodes or not.
iterator():
return an iterator of all the elements stored at nodes of the tree.
positions():
return an iterable collection of all the nodes of the tree.
replace(v,e):
Replace with e and return the element stored at node v.
Any method that takes a position as an argument should generate an error condition
if that position is invalid. We do not define any specialized update methods for trees
here. Instead, we prefer to describe different tree update methods in conjunction
with specific applications of trees in subsequent chapters. In fact, we can imagine
several kinds of tree update operations beyond those given in this book.
7.1.3 Implementing a Tree
The Java interface shown in Code Fragment 7.1 represents the tree ADT. Error
conditions are handled as follows: Each method that can take a position as an
argument, may throw an InvalidPositionException, to indicate that the
position is invalid. Method parent throws a BoundaryViolationException
if it is called on the root. Method root throws an EmptyTreeException if it is
called on an empty tree.
Code Fragment 7.1: Java interface Tree
representing the tree ADT. Additional update methods
may be added, depending on the application. We do
not include such methods in the interface, however.
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