Collections-Tutorial - Collection Framework (Extracted from...

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Collection Framework (Extracted from Sun Java Tutorial at: http://java.sun.com/docs/books/tutorial/collections/interfaces/index.html) The core collection interfaces encapsulate different types of collections, which are shown in the figure below. These interfaces allow collections to be manipulated independently of the details of their representation. Core collection interfaces are the foundation of the Java Collections Framework. As you can see in the following figure, the core collection interfaces form a hierarchy. The core collection interfaces. A Set is a special kind of Collection , a SortedSet is a special kind of Set , and so forth. Note also that the hierarchy consists of two distinct trees — a Map is not a true Collection . Note that all the core collection interfaces are generic. For example, this is the declaration of the Collection interface. public interface Collection<E>. .. The <E> syntax tells you that the interface is generic. When you declare a Collection instance you can and should specify the type of object contained in the collection. Specifying the type allows the compiler to verify (at compile-time) that the type of object you put into the collection is correct, thus reducing errors at runtime. For information on generic types, see the Generics lesson. When you understand how to use these interfaces, you will know most of what there is to know about the Java Collections Framework. This chapter discusses general guidelines for effective use of the interfaces, including when to use which interface. You'll also learn programming idioms for each interface to help you get the most out of it. To keep the number of core collection interfaces manageable, the Java platform doesn't provide separate interfaces for each variant of each collection type. (Such variants might include immutable, fixed-size, and append-only.) Instead, the modification operations in each interface are designated optional — a given implementation may elect not to support all operations. If an unsupported operation is invoked, a collection throws an UnsupportedOperationException . Implementations are responsible for documenting which of the optional operations they support. All of the Java platform's general-purpose implementations support all of the optional operations. The following list describes the core collection interfaces: Collection — the root of the collection hierarchy. A collection represents a group of objects known as its elements . The Collection interface is the least common denominator that all collections implement and is used to pass collections around and to manipulate them when maximum generality is desired. Some types of collections allow duplicate elements, and others do not. Some are ordered and others are unordered. The Java platform doesn't provide any direct implementations of this interface but provides implementations of more specific subinterfaces, such as Set and List . Also see The Collection Interface section. Set
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This note was uploaded on 09/26/2009 for the course EE 322C taught by Professor Nettles during the Spring '08 term at University of Texas at Austin.

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Collections-Tutorial - Collection Framework (Extracted from...

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