Java collections framework
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The document outlines the Java Collections Framework (JCF), detailing its history, key components, and various collection types and interfaces such as List, Set, and Map. It emphasizes the framework's role in providing a unified architecture for collection manipulation and its methods. Additionally, it discusses concurrency support and the concepts of iterators and generics within the collection interfaces.
![Collection interface
A.A. 2012/2013Tecniche di programmazione16
public interface Collection<E> extends Iterable<E> {
int size();
boolean isEmpty();
boolean contains(Object element);
boolean add(E element); //optional
boolean remove(Object element); //optional
Iterator<E> iterator();
boolean containsAll(Collection<?> c);
boolean addAll(Collection<? extends E> c); //optional
boolean removeAll(Collection<?> c); //optional
boolean retainAll(Collection<?> c); //optional
void clear(); //optional
Object[] toArray();
<T>T[] toArray(T[] a);
}](https://image.slidesharecdn.com/w02b-collection-130417051744-phpapp02/85/Java-collections-framework-16-320.jpg)
![Collection interface
A.A. 2012/2013Tecniche di programmazione17
public interface Collection<E> extends Iterable<E> {
int size();
boolean isEmpty();
boolean contains(Object element);
boolean add(E element); //optional
boolean remove(Object element); //optional
Iterator<E> iterator();
boolean containsAll(Collection<?> c);
boolean addAll(Collection<? extends E> c); //optional
boolean removeAll(Collection<?> c); //optional
boolean retainAll(Collection<?> c); //optional
void clear(); //optional
Object[] toArray();
<T>T[] toArray(T[] a);
}
Basic Operations
generics](https://image.slidesharecdn.com/w02b-collection-130417051744-phpapp02/85/Java-collections-framework-17-320.jpg)
![Collection interface
A.A. 2012/2013Tecniche di programmazione18
public interface Collection<E> extends Iterable<E> {
int size();
boolean isEmpty();
boolean contains(Object element);
boolean add(E element); //optional
boolean remove(Object element); //optional
Iterator<E> iterator();
boolean containsAll(Collection<?> c);
boolean addAll(Collection<? extends E> c); //optional
boolean removeAll(Collection<?> c); //optional
boolean retainAll(Collection<?> c); //optional
void clear(); //optional
Object[] toArray();
<T>T[] toArray(T[] a);
}
Bulk Operations
wildcard
either extends
or implements](https://image.slidesharecdn.com/w02b-collection-130417051744-phpapp02/85/Java-collections-framework-18-320.jpg)
![Collection interface
A.A. 2012/2013Tecniche di programmazione19
public interface Collection<E> extends Iterable<E> {
int size();
boolean isEmpty();
boolean contains(Object element);
boolean add(E element); //optional
boolean remove(Object element); //optional
Iterator<E> iterator();
boolean containsAll(Collection<?> c);
boolean addAll(Collection<? extends E> c); //optional
boolean removeAll(Collection<?> c); //optional
boolean retainAll(Collection<?> c); //optional
void clear(); //optional
Object[] toArray();
<T>T[] toArray(T[] a);
}
Array Operations](https://image.slidesharecdn.com/w02b-collection-130417051744-phpapp02/85/Java-collections-framework-19-320.jpg)
Java collections framework
- 1. Java collections framework Commonly reusable collection data structures
- 2. Java Collections Framework (JCF) A.A. 2012/2013Tecniche di programmazione2 Collection an object that represents a group of objects Collection Framework A unified architecture for representing and manipulating collections Such collections are manipulated independent of the details of their representation “JCF” vs.“ADT”
- 3. A little bit of history… A.A. 2012/2013Tecniche di programmazione3 JDK < 1.2 Standard practice: Vector and Hashtable Compatibility with C++ StandardTemplate Library (STL) Doug Lea’s Collections package ObjectSpace Generic Collection Library (JGL) JDK ≥1.2 Sun drops compatibility with C++ STL Joshua Bloch’s JCF (now Chief Java Architect @ Google)
- 4. A little bit of history… A.A. 2012/2013Tecniche di programmazione4 Java 5 Introduction of <generics> Clean, safe definition of the Collection Interface Trees, linked lists, stacks, hash tables, and other classes are implementations of Collection Arrays do not implement the Collection interface Vector redefined to implement Collection
- 5. A little bit of history… A.A. 2012/2013Tecniche di programmazione5 Doug Lea later developed a concurrency package
- 6. JCF’s Main Elements A.A. 2012/2013Tecniche di programmazione6 Infrastructure Interfaces that provide essential support for the collection interfaces General-purpose Implementations Primary implementations (basic and bulk) of the collection interfaces
- 7. Algorithms A.A. 2012/2013Tecniche di programmazione7 Algorithms Static methods that perform useful functions on collections, such as sorting a list
- 8. ICF’s Utility Implementations A.A. 2012/2013Tecniche di programmazione8 Legacy Implementations The collection classes from earlier releases,Vector and Hashtable, have been retrofitted to implement the collection interfaces Convenience Implementations High-performance "mini-implementations" of the collection interfaces Wrapper Implementations Add functionality, such as synchronization, to other implementations
- 9. Abstract Implementations A.A. 2012/2013Tecniche di programmazione9 Partial implementations (skeletons) of the collection interfaces to facilitate custom implementations
- 10. Infrastructure A.A. 2012/2013Tecniche di programmazione10 These interfaces form the basis of the framework Some types of collections allow duplicate elements, others do not Some types of collections are ordered, others are unordered The Java platform doesn’t provide any direct implementations of the Collection interface, but provides implementations of more specific sub-interfaces, such as Set and List and Maps
- 11. Collection interface A.A. 2012/2013Tecniche di programmazione11 A Collection represents a group of objects known as its elements The Collection interface is the least common denominator that all collections implement. It is Used to pass collections around to manipulate them when maximum generality is desire Collection extends Iterable
- 12. A note on iterators A.A. 2012/2013Tecniche di programmazione12 An Iterator is an object that enables you to traverse through a collection (and to remove elements from the collection selectively) You get an Iterator for a collection by calling its iterator() method. Several languages supports “iterators”. E.g., C++, PHP, Python, Ruby, Go… public interface Iterator<E> { boolean hasNext(); E next(); void remove(); //optional }
- 13. Main Interfaces A.A. 2012/2013Tecniche di programmazione13 List A more flexible version of an array Queue & Priority Queue The order of arrival does matter, or the urgency Set No order, no duplicate elements
- 14. Map interface A.A. 2012/2013Tecniche di programmazione14 A Map is an object that maps keys to values A map cannot contain duplicate keys: each key can map to at most one value Map does not extend Iterable, but it is possible to get an iterator through entrySet() Notez bien: Maps do not extend from java.util.Collection, but they’re still considered to be part of the “collections framework”
- 15. Collection Family Tree A.A. 2012/2013Tecniche di programmazione15
- 16. Collection interface A.A. 2012/2013Tecniche di programmazione16 public interface Collection<E> extends Iterable<E> { int size(); boolean isEmpty(); boolean contains(Object element); boolean add(E element); //optional boolean remove(Object element); //optional Iterator<E> iterator(); boolean containsAll(Collection<?> c); boolean addAll(Collection<? extends E> c); //optional boolean removeAll(Collection<?> c); //optional boolean retainAll(Collection<?> c); //optional void clear(); //optional Object[] toArray(); <T>T[] toArray(T[] a); }
- 17. Collection interface A.A. 2012/2013Tecniche di programmazione17 public interface Collection<E> extends Iterable<E> { int size(); boolean isEmpty(); boolean contains(Object element); boolean add(E element); //optional boolean remove(Object element); //optional Iterator<E> iterator(); boolean containsAll(Collection<?> c); boolean addAll(Collection<? extends E> c); //optional boolean removeAll(Collection<?> c); //optional boolean retainAll(Collection<?> c); //optional void clear(); //optional Object[] toArray(); <T>T[] toArray(T[] a); } Basic Operations generics
- 18. Collection interface A.A. 2012/2013Tecniche di programmazione18 public interface Collection<E> extends Iterable<E> { int size(); boolean isEmpty(); boolean contains(Object element); boolean add(E element); //optional boolean remove(Object element); //optional Iterator<E> iterator(); boolean containsAll(Collection<?> c); boolean addAll(Collection<? extends E> c); //optional boolean removeAll(Collection<?> c); //optional boolean retainAll(Collection<?> c); //optional void clear(); //optional Object[] toArray(); <T>T[] toArray(T[] a); } Bulk Operations wildcard either extends or implements
- 19. Collection interface A.A. 2012/2013Tecniche di programmazione19 public interface Collection<E> extends Iterable<E> { int size(); boolean isEmpty(); boolean contains(Object element); boolean add(E element); //optional boolean remove(Object element); //optional Iterator<E> iterator(); boolean containsAll(Collection<?> c); boolean addAll(Collection<? extends E> c); //optional boolean removeAll(Collection<?> c); //optional boolean retainAll(Collection<?> c); //optional void clear(); //optional Object[] toArray(); <T>T[] toArray(T[] a); } Array Operations
- 21. Licenza d’uso A.A. 2012/2013Tecniche di programmazione21 Queste diapositive sono distribuite con licenza Creative Commons “Attribuzione - Non commerciale - Condividi allo stesso modo (CC BY-NC-SA)” Sei libero: di riprodurre, distribuire, comunicare al pubblico, esporre in pubblico, rappresentare, eseguire e recitare quest'opera di modificare quest'opera Alle seguenti condizioni: Attribuzione — Devi attribuire la paternità dell'opera agli autori originali e in modo tale da non suggerire che essi avallino te o il modo in cui tu usi l'opera. Non commerciale — Non puoi usare quest'opera per fini commerciali. Condividi allo stesso modo — Se alteri o trasformi quest'opera, o se la usi per crearne un'altra, puoi distribuire l'opera risultante solo con una licenza identica o equivalente a questa. http://creativecommons.org/licenses/by-nc-sa/3.0/