Java in a Nutshell, 5th Edition

Java Platform Overview

Table 5-1 summarizes the key packages of the Java platform that are covered in this book.

Table 5-1. Key packages of the Java platform

Package	Description
java.io	Classes and interfaces for input and output. Although some of the classes in this package are for working directly with files, most are for working with streams of bytes or characters.
java.lang	The core classes of the language, such as String, Math, System, Thread, and Exception.
java.lang.annotation	Annotation types and other supporting types for the Java 5.0 annotation feature. (See Chapter 4.)
java.lang.instrument	Support classes for Java virtual machine instrumentation agents, which are allowed to modify the byte code of the program the JVM is running. New in Java 5.0.
java.lang.management	A framework for monitoring and managing a running Java virtual machine. New in Java 5.0.
java.lang.ref	Classes that define weak references to objects. A weak reference is one that does not prevent the referent object from being garbage-collected.
java.lang.reflect	Classes and interfaces that allow Java programs to reflect on themselves by examining the constructors, methods, and fields of classes.
java.math	A small package that contains classes for arbitrary-precision integer and floating-point arithmetic.
java.net	Classes and interfaces for networking with other systems.
java.nio	Buffer classes for the New I/O API. Added in Java 1.4.
java.nio.channels ...