The Java Tutorials have been written for JDK 8. Examples and practices described in this page don't take advantage of improvements introduced in later releases and might use technology no longer available.
SeeDev.java for updated tutorials taking advantage of the latest releases.
SeeJava Language Changes for a summary of updated language features in Java SE 9 and subsequent releases.
SeeJDK Release Notes for information about new features, enhancements, and removed or deprecated options for all JDK releases.

Creating and Using Packages

To make types easier to find and use, to avoid naming conflicts, and to control access, programmers bundle groups of related types into packages.

The types that are part of the Java platform are members of various packages that bundle classes by function: fundamental classes are injava.lang, classes for reading and writing (input and output) are injava.io, and so on. You can put your types in packages too.

Suppose you write a group of classes that represent graphic objects, such as circles, rectangles, lines, and points. You also write an interface,Draggable, that classes implement if they can be dragged with the mouse.

//in the Draggable.java filepublic interface Draggable {    ...}//in the Graphic.java filepublic abstract class Graphic {    ...}//in the Circle.java filepublic class Circle extends Graphic    implements Draggable {    . . .}//in the Rectangle.java filepublic class Rectangle extends Graphic    implements Draggable {    . . .}//in the Point.java filepublic class Point extends Graphic    implements Draggable {    . . .}//in the Line.java filepublic class Line extends Graphic    implements Draggable {    . . .}

You should bundle these classes and the interface in a package for several reasons, including the following:

• You and other programmers can easily determine that these types are related.
• You and other programmers know where to find types that can provide graphics-related functions.
• The names of your types won't conflict with the type names in other packages because the package creates a new namespace.
• You can allow types within the package to have unrestricted access to one another yet still restrict access for types outside the package.