Home arrow Java & J2EE arrow Taming Tiger: Concurrent Collections

Taming Tiger: Concurrent Collections

Moving beyond Map, Collection, List, and Set: John Zukowski discusses the new library release in the Tiger release of the J2SE platform and what it provides: a set of utilities commonly needed in concurrent programs. If you are interested in optimizing multithreaded access to your collections, you've come to the right place. (This intermediate-level article was first published by IBM developerWorks, June 16, 2004, at http://www.ibm.com/developerWorks.)

TABLE OF CONTENTS:
  1. Taming Tiger: Concurrent Collections
  2. Using the Basic Queues
  3. Using the Blocking Queues
  4. Using the ConcurrentMap implementation
  5. Resources
By: developerWorks
Rating: starstarstarstarstar / 11
October 27, 2004

print this article
SEARCH DEV SHED

TOOLS YOU CAN USE

advertisement

What began as author Doug Lea's util.concurrent package has morphed into JSR-166 and into the Tiger release of the J2SE platform. What the new library provides is a set of utilities commonly needed in concurrent programs. If you are interested in optimizing multithreaded access to your collections, you've come to the right place. Share your thoughts on this article with the author, John Zukowski, and other readers in the accompanying discussion forum.

In the early days of Java programming, a professor from the State University of New York (SUNY) College at Oswego decided to create a simple library to help developers build applications that were better able to handle multithreaded situations. This isn't to say you couldn't get by with the existing libraries, but just like having a standard networking library, it was easier to do multithreading yourself with a debugged, trusted library. With the help of a related book from Addison-Wesley, over time this library became popular. Eventually, the author, Doug Lea, decided to pursue making it a standard part of the Java platform as JSR-166. What that library has morphed into is the java.util.concurrent package of the Tiger release. In this Taming Tiger tip, you'll explore the new Queue interface in the Collections Framework, the non-concurrent and concurrent implementations of that interface, a concurrent Map implementation, and special-purpose concurrent List and Set implementations for when read operations heavily exceed write operations.

Introducing the Queue interface

The java.util package offers a new base interface for collections: java.util.Queue. While you certainly can treat a java.util.List as a queue by adding and removing from opposite ends, what the new Queue interface offers is additional methods to support adding, removing, and inspecting the collection, as shown below:

public boolean offer(Object element)
public Object remove()
public Object poll()
public Object element()
public Object peek()

Basically, a queue is a first-in, first-out (FIFO) data structure. Some queues are restricted in size, so when you want to add a new item to a full queue, the additional item is rejected. That's where the new offer method comes into play. Instead of throwing an unchecked exception with a call to the add() method, you just get false returned by offer(). The remove() and poll() methods are both for removing the first element (head) of the queue. While remove() behaves like the Collection interface version, instead of throwing an exception when called with an empty collection, the new poll() method just returns null. The newer methods are thus more for when the exceptional condition is the norm. The last two methods, element() and peek(), are for querying the element at the head of the queue. Like the remove() method, element() throws an exception when the queue is empty, whereas peek() returns null.

IBM developerWorksVisit developerWorks for thousands of developer articles, tutorials, and resources related to open standard technologies, IBM products, and more. See developerWorks.



 
 
>>> More Java & J2EE Articles          >>> More By developerWorks
 

blog comments powered by Disqus
escort Bursa Bursa escort Antalya eskort
   

JAVA & J2EE ARTICLES

- More Java Bugs Lead to More Attacks
- Oracle's Java One Brings News, Surprises
- Oracle Patches Java Runtime Environment
- Apple Syncs Java Update with Oracle
- Spring 3.1 Java Development Framework Compat...
- Jelastic Java PaaS Availability and Pricing ...
- NetBeans 7.1 Released, Supports JavaFX 2
- SolarWinds Releases Newest Version of Java M...
- Free Monitoring Tool for Java Apps on Heroku
- Heroku Adds JCloud Platform Support, Java 7 ...
- Java SE 8 Speculation in Full Swing
- Java SE 7 Now Available
- New JVM Language and Java Reporting Tool
- Java 7 Release Update and New Eclipse Toolkit
- The Best Java Netbeans IDE Plugins

Developer Shed Affiliates

 


Dev Shed Tutorial Topics: