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The introduction of the Collections API by Sun in JDK 1.2 has been a boon to quick and effective Java programming. Ready access to powerful data structures has accelerated development by reducing the need for custom container classes around each core object. Most Java2 APIs are significantly easier to use because of the Collections API. However, there are certain holes left unfilled by Sun's implementations, and the Jakarta-Commons Collections Component strives to fulfill them. Among the features of this package are: - special-purpose implementations of Lists and Maps for fast access - adapter classes from Java1-style containers (arrays, enumerations) to Java2-style collections. - methods to test or create typical set-theory properties of collections such as union, intersection, and closure.
Testframework for apache-commons-collections.
The Apache Commons Compress library defines an API for working with ar, cpio, Unix dump, tar, zip, gzip, XZ, Pack200 and bzip2 files.
Configuration is a project to provide a generic Configuration interface and allow the source of the values to vary. It provides easy typed access to single, as well as lists of configuration values based on a 'key'. Right now you can load properties from a simple properties file, a properties file in a jar, an XML file, JNDI settings, as well as use a mix of different sources using a ConfigurationFactory and CompositeConfiguration. Custom configuration objects are very easy to create now by just subclassing AbstractConfiguration. This works similar to how AbstractList works.
The scope of this package is to define an API in line with the current Java Platform APIs to support an alternative invocation mechanism which could be used instead of the public static void main(String[]) method. This specification covers the behavior and life cycle of what we define as Java daemons, or, in other words, non interactive Java applications.
Java daemon launcher.
Many Apache projects support interaction with a relational database. Creating a new connection for each user can be time consuming (often requiring multiple seconds of clock time), in order to perform a database transaction that might take milliseconds. Opening a connection per user can be unfeasible in a publicly-hosted Internet application where the number of simultaneous users can be very large. Accordingly, developers often wish to share a "pool" of open connections between all of the application's current users. The number of users actually performing a request at any given time is usually a very small percentage of the total number of active users, and during request processing is the only time that a database connection is required. The application itself logs into the DBMS, and handles any user account issues internally.
Many projects read XML configuration files to provide initialization of various Java objects within the system. There are several ways of doing this, and the Digester component was designed to provide a common implementation that can be used in many different projects
An implementation of standard interfaces and abstract classes for javax.servlet.jsp.el which is part of the JSP 2.0 specification.
Commons Exec is a library for dealing with external process execution and environment management in Java.