Tree

All Superinterfaces:

Iterable<E>

All Known Subinterfaces:

BinaryTree<E>

All Known Implementing Classes:

AbstractBinaryTree, AbstractTree, LinkedBinaryTree, LinkedTree, TreeMap.BalanceableBinaryTree
```
public interface Tree<E>
extends Iterable<E>
```
An interface for a tree where nodes can have an arbitrary number of children.

Method Summary

Methods
Modifier and Type	Method and Description
`Iterable<Position<E>>`	`children(Position<E> p)` Returns an iterable collection of the Positions representing p's children.
`boolean`	`isEmpty()` Tests whether the tree is empty.
`boolean`	`isExternal(Position<E> p)` Returns true if Position p does not have any children.
`boolean`	`isInternal(Position<E> p)` Returns true if Position p has one or more children.
`boolean`	`isRoot(Position<E> p)` Returns true if Position p represents the root of the tree.
`Iterator<E>`	`iterator()` Returns an iterator of the elements stored in the tree.
`int`	`numChildren(Position<E> p)` Returns the number of children of Position p.
`Position<E>`	`parent(Position<E> p)` Returns the Position of p's parent (or null if p is root).
`Iterable<Position<E>>`	`positions()` Returns an iterable collection of the positions of the tree.
`Position<E>`	`root()` Returns the root Position of the tree (or null if tree is empty).
`int`	`size()` Returns the number of nodes in the tree.

- Method Detail
  - root
```
Position<E> root()
```
    Returns the root Position of the tree (or null if tree is empty).
    
    Returns:
    root Position of the tree (or null if tree is empty)
  - parent
```
Position<E> parent(Position<E> p)
                   throws IllegalArgumentException
```
    Returns the Position of p's parent (or null if p is root).
    
    Parameters:
    p - A valid Position within the tree
    
    Returns:
    Position of p's parent (or null if p is root)
    
    Throws:
    
    IllegalArgumentException - if p is not a valid Position for this tree.
  - children
```
Iterable<Position<E>> children(Position<E> p)
                               throws IllegalArgumentException
```
    Returns an iterable collection of the Positions representing p's children.
    
    Parameters:
    p - A valid Position within the tree
    
    Returns:
    iterable collection of the Positions of p's children
    
    Throws:
    
    IllegalArgumentException - if p is not a valid Position for this tree.
  - numChildren
```
int numChildren(Position<E> p)
                throws IllegalArgumentException
```
    Returns the number of children of Position p.
    
    Parameters:
    p - A valid Position within the tree
    
    Returns:
    number of children of Position p
    
    Throws:
    
    IllegalArgumentException - if p is not a valid Position for this tree.
  - isInternal
```
boolean isInternal(Position<E> p)
                   throws IllegalArgumentException
```
    Returns true if Position p has one or more children.
    
    Parameters:
    p - A valid Position within the tree
    
    Returns:
    true if p has at least one child, false otherwise
    
    Throws:
    
    IllegalArgumentException - if p is not a valid Position for this tree.
  - isExternal
```
boolean isExternal(Position<E> p)
                   throws IllegalArgumentException
```
    Returns true if Position p does not have any children.
    
    Parameters:
    p - A valid Position within the tree
    
    Returns:
    true if p has zero children, false otherwise
    
    Throws:
    
    IllegalArgumentException - if p is not a valid Position for this tree.
  - isRoot
```
boolean isRoot(Position<E> p)
               throws IllegalArgumentException
```
    Returns true if Position p represents the root of the tree.
    
    Parameters:
    p - A valid Position within the tree
    
    Returns:
    true if p is the root of the tree, false otherwise
    
    Throws:
    
    IllegalArgumentException - if p is not a valid Position for this tree.
  - size
```
int size()
```
    Returns the number of nodes in the tree.
    
    Returns:
    number of nodes in the tree
  - isEmpty
```
boolean isEmpty()
```
    Tests whether the tree is empty.
    
    Returns:
    true if the tree is empty, false otherwise
  - iterator
```
Iterator<E> iterator()
```
    Returns an iterator of the elements stored in the tree.
    
    Specified by:
    
    iterator in interface Iterable<E>
    
    Returns:
    iterator of the tree's elements
  - positions
```
Iterable<Position<E>> positions()
```
    Returns an iterable collection of the positions of the tree.
    
    Returns:
    iterable collection of the tree's positions

Interface Tree<E>

Method Summary

Method Detail

root

parent

children

numChildren

isInternal

isExternal

isRoot

size

isEmpty

iterator

positions