Enterprise System EssentialsCore to Java EEEnterprise System
EssentialsCollectionsNetwork Programming (TCP /
UDP)CollectionGenericsCollectionA collection is a container object
that holds a group of objects known as elements.It contains
operations for Adding, Updating, and Removing elements A
Collections framework is a unified architecture for representing
and manipulating collections. It has: Interfaces: abstract data
types representing collectionsImplementations: concrete
implementations of the collection interfacesAlgorithms: methods
that perform useful computations, such as searching and
sortingThese algorithms are said to be polymorphic: the same method
can be used on different implementationsCollection Interface
5Collection Interface
6Collection Interface
7Wildcards in CollectionClasses and interfaces in the collection
framework can have parameter type specifications that do not fully
specify the type plugged in for the type parameterBecause they
specify a wide range of argument types, they are known as
wildcards
public void method(String arg1, ArrayList arg2)
In the above example, the first argument is of type String,
while the second argument can be an ArrayList with any base typeA
bound can be placed on a wildcard specifying that the type used
must be an ancestor type or descendent type of some class or
interfaceThe notation
