This chapter covers the java.lang package which defines the core classes and interfaces that are indispensable to the Java platform and the Java programming language. It also covers more specialized subpackages:
java.lang.annotation
Defines the Annotation interface that all annotation types extend, and also defines meta-annotation types and related enumerated types. Added in Java 5.0.
java.lang.instrument
Provides support for Java-based " agents " that can instrument a Java program by transforming class files as they are loaded. Added in Java 5.0.
java.lang.management
Defines "management bean" interfaces for remote monitoring and management of a running Java interpreter.
java.lang.ref
Defines "reference" classes that are used to refer to objects without preventing the garbage collector from reclaiming those objects.
java.lang.reflect
Allows Java programs to examine the members of arbitrary classes, invoking methods , and querying and setting the value of fields.