java.lang.* and java.util.* Packages

java.lang - Provides classes that are fundamental to the design of the Java programming language.
java.lang.annotation - Provides library support for the Java programming language annotation facility.
java.lang.instrument - Provides services that allow Java programming language agents to instrument programs running on the JVM.
java.lang.management - Provides the management interface for monitoring and management of the Java virtual machine as well as the operating system on which the Java virtual machine is running.
java.lang.ref - Provides reference-object classes, which support a limited degree of interaction with the garbage collector.
java.lang.reflect - Provides classes and interfaces for obtaining reflective information about classes and objects.
java.util - Contains the collectsions framework, legacy collection classes, event model, date and time facilities, internationalization, and miscellaneous utility classes (a string tokenizer, a random-number generator, and a bit array).
java.util.concurrent - Utility classes commonly useful in concurrent programming.
java.util.concurrent.atomic - A small toolkit of classes that support lock-free thread-safe programming on single variables.
java.util.concurrent.locks - Interfaces and classes providing a framework for locking and waiting for conditions that is distinct from built-in synchronization and monitors.
java.util.jar - Provides classes for reading and writing the JAR (Java ARchive) file format, which is based on the standard ZIP file format with an optional manifest file.
java.util.logging - Provides the classes and interfaces of the Java 2 platform's core logging facilities.
java.util.regex - Classes for matching character sequences against patterns specified by regular expressions.
java.util.prefs - This package allows applications to store and retrieve user and system preference and configuration data.
java.util.spi - Service provider classes for the classes in the java.util package.
java.util.zip - Provides classes for reading and writing the standard ZIP and GZIP file formats.