The java.lang and java.util.* Packages
The java.lang package provides classes that are fundamental to the design of the JavaTM programming language.
The java.util.* packages provide support for the event model, collections framework, date and time facilities, and contains various utility classes. The java.util.zip and java.util.jar packages provide support for ZIP file format and Java Archive (JAR) file formats respectively.
Version 1.3 of the Java 2 SDK offers several enhancements in the java.lang and java.util.* packages. See Enhancements for details.