Generic Collections - Java: How to Program Early Objects - page 723

and class TreeSet for manipulating a sorted collection of unique values. You then learned
about Java's interfaces and classes for manipulating key-value pairs— Map , SortedMap ,
Hashtable , HashMap and TreeMap . We discussed the specialized Properties class for ma-
nipulating key-value pairs of String s that can be stored to a file and retrieved from a file.
Finally, we discussed the Collections class's static methods for obtaining unmodifiable
and synchronized views of collections. For additional information on the collections
framework, visit http://docs.oracle.com/javase/7/docs/technotes/guides/col-
lections . In Chapter 17, Java SE 8 Lambdas and Streams, you'll use Java SE 8's new
functional programming capabilities to simplify collection operations. In Chapter 23,
Concurrency, you'll learn how to improve performance on multi-core systems using Java's
concurrent collections and parallel stream operations.
Summary
Section 16.1 Introduction
• The Java collections framework provides prebuilt data structures and methods to manipulate
them.
Section 16.2 Collections Overview
• A collection is an object that can hold references to other objects.
• The classes and interfaces of the collections framework are in package java.util .
Section 16.3 Type-Wrapper Classes
• Type-wrapper classes (e.g., Integer , Double , Boolean ) enable programmers to manipulate prim-
itive-type values as objects (p. 687). Objects of these classes can be used in collections.
Section 16.4 Autoboxing and Auto-Unboxing
• Boxing (p. 687) converts a primitive value to an object of the corresponding type-wrapper class.
Unboxing (p. 687) converts a type-wrapper object to the corresponding primitive value.
• Java performs boxing conversions and unboxing conversions automatically.
Section 16.5 Interface Collection and Class Collections
• Interfaces Set and List extend Collection (p. 686), which contains operations for adding, clear-
ing, comparing and retaining objects in a collection, and method iterator (p. 691) to obtain a
collection's Iterator (p. 687).
• Class Collections (p. 688) provides static methods for manipulating collections.
Section 16.6 Lists
•A List (p. 694) is an ordered Collection that can contain duplicate elements.
• Interface List is implemented by classes ArrayList , LinkedList and Vector . ArrayList (p. 688)
is a resizable-array implementation. LinkedList (p. 688) is a linkedlist implementation of a List .
• Java SE 7 supports type inferencing with the <> notation in statements that declare and create
generic type variables and objects.
• Iterator method hasNext (p. 691) determines whether a Collection contains another element.
Method next returns a reference to the next object in the Collection and advances the Iterator .
•Method subList (p. 694) returns a view into a List . Changes made to this view are also made
to the List .