Core Web Programming, Second Edition

7.10. Packages, Classpath, and JAR Archives

Java lets you group class libraries into separate modules or “packages” to avoid naming conflicts and to simplify their handling. For instance, in a real project, the Ship and Shape class hierarchies would have been easier to create and use if placed in separate packages. To create a package called packagename, first make a subdirectory with the same name and place all source files there. Each of these files should contain

package packagename;

as the first noncomment line. Files that lack a package declaration are automatically placed in an unnamed package. Files in the main directory that want to use the package should include

import packagename.ClassName;

or

import packagename.*;

before the ...