8 Programming Large Java Card Applications with Multiple Packages

SinceJava Card Version 3.1, multiple Java packages can be bundled into one Java Card CAP file using an extended CAP file format.

This feature enables you to:

• Keep a modular design by having applications or libraries made of multiple packages.
• Distribute an application with the libraries it relies on.
• Control the visibility of each of the packages deployed in a CAP file.
• Overcome the size limitation of 64 K in compact CAP files.

The converter uses the extended CAP file format when multiple packages are used in a single CAP file or when the converted code for the whole CAP file exceeds the size of 64 KB.

The Java Card products optionally supports the extended CAP file. Before using this extended CAP file format, it is important to check if the target Java Card product supports this feature or not.

Refer to JavaCard Platform Virtual Machine Specification, Classic Edition, Version 3.2, for more information on the CAP file and its format.

Topics:

• CAP File Identification
• PackageVisibility
• Firewall Context
• Extended CAP Accessibility Example
• Design Rules for a Java Card Application with Large Method Component