Java The Complete Reference, Seventh Edition

16 Exploring java.lang

16 Exploring java.lang

T

his chapter discusses thos e classes and interfaces defined byjava.lang. As you know,
java.langis automatically imported into all programs. It contains classes and interfaces
that are fundamental to virtually all of Java programming. It is Java’s most widely
used package.
java.langincludes the following classes:

Boolean InheritableThreadLocal Runtime System

Byte Integer RuntimePermission Thread

Character Long SecurityManager ThreadGroup

Class Math Short ThreadLocal

ClassLoader Number StackTraceElement Throwable

Compiler Object StrictMath Void

Double Package String

Enum Process StringBuffer

Float ProcessBuilder StringBuilder

There are also two classes defined by theCharacterclass:Character.Subsetand
Character.UnicodeBlock.
java.langdefines the following interfaces:

Appendable Comparable Runnable

CharSequence Iterable

Cloneable Readable

Several of the classes contained injava.langcontain deprecated methods, most dating
back to Java 1.0. These deprecated methods are still provided by Java to support an ever-
shrinking pool of legacy code and are not recommended for new code. Most of the deprecations
took place prior to Java SE 6, and these deprecated methods are not discussed here.

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