CS 335/535 Web Programming - Java Advanced Data Structures

• Self-Referential Classes - contains a reference member that refers to a class object of the same class type ex.
  

  	class Node {
  		Object data;
  		Node next;
  
  		Node (Object obj) {
  			data = obj;
  			next = null;		
   		}
  
  		Node (Object obj, Node nextNode) {
  			data = obj;
  			next = nextNode;		
   		}
  
  		Object getObject () { return data;}
  		Node getNext () { return next;}
  

• Dynamic Memory Allocation: Node nodeToAdd = new Node ( 10 );

java.util

• Enumeration (Interface): specifies a set of methods that may be used to interate through a set of values
  • boolean hasMoreElements()
  • Object nextElement() [throws NoSuchElementException]
• Vector - implements a growable array
  • Vector()
  • Vector(int initialCapacity [, int capacityIncrement])
  
  
  • final synchronized void addElement(Object obj) // adds object to the end of the Vector
  • final synchronized Object clone() // clones the Vector but not its elements
  • final boolean contains(Object element) // returns true if specified element is in this Vector
  • final synchronized void copyInto(Object objArray[]) // copys this vector into specified array
  • final synchronized Object elementAt(int index) // returns element at the given index of this vector
  • final synchronized Object firstElement() // returns first element in this Vector
  • final synchronized void insertElementAt(Object obj, int index) // inserts object at the given index of this vector and reindexes this Vector
  • final boolean isEmpty() // returns true if this Vector contains no elements
  • final synchronized Object lastElement() // returns the last element in this Vector
  • final synchronized void removeElementAt(int index) // deletes the element at the specified index position and reindexes this Vector
  • final synchronized void setElementAt(Object obj, int index) // overwrites the element at specified index position with the given Object
  • final int size() // returns the current number of elements in this Vector
  • final synchronized String toString() // returns a String showing all the elements in this Vector
  • final synchronized void trimToSize() // trims this Vector's capacity to the current size
• Stacks [Parent class - Vector]
  • Stack() // constructor
  • boolean empty() // returns true if this Stack is empty
  • Object peek() // returns a reference to the Object at the top of this Stack
  • Object pop() // pops an object of this Stack
  • Object push (Object obj) // pushes an Object onto this Stack and returns the same item
  • int Search(Object obj) //returns the distance obj is from the top of this Stack (or -1 if not found0
• Dictionary abstract parent class of Hashtable which maps keys to values
  • abstract Enumeration elements() // returns an enumeration of the elements in this Dictionary
  • abstract Object get(Object key) // returns the object associated with the specified key in this Dictionary
  • abstract boolean isEmpty() // returns true if there are no elements in this Dictionary
  • abstract Enumeration keys() // returns an enumeration of this Dictionary's keys
  • abstract Object put(Object key, Object value) // puts the specified value into this Dictionary, using the specified key
  • abstract Object remove (Object key) // removes the element associated with the specifed key
  • abstract int size() // returns the number of elements in this Dictionary
• Hashtable uses a unique key to access data placed in the table. The key can be any object as long as it implements the hashCode() and equals() methods. Hashtables will automatically grow.
  • Hashtable() // default constructor
  • Hashtable(int intialCapacity [, float loadFactor]) // constructs a new, empty table with the specified intialCapacity in buckets and a loadFactor between 0 and 1 that defines the threshold for rehashing the table into a larger one
  • synchronized void clear() // clears this Hashtable of all its elements
  • synchronized Object clone () // creats a shallow copy of this Hashtable
  • synchronized boolean contains(Object lookingFor) // returns true if the specified object is an element of the Hashtable
  • synchronized boolean containsKey(Object findKey) // returns true if the specified object findKey is defined in the Hashtable
  • synchronized void rehash() // rehashes the content of the table into a larger one
  • String toString() // returns the String showing this Hashtable