01. Introduction to Modules

Introduction to Modules

Project Jigsaw

Our dependency examples have been simple, but libraries that use other libraries eventually create a very complex dependency chain. Project Jigsaw was the effort to declare dependency relationships in a way that would allow Java to recognize library dependencies and control package-level visibility based on those dependencies. Eventually, the changes implemented by Project Jigsaw were merged into Java 9 and became the Module system.

Benefits of controlling package visibility and dependency relationship at compile time:

• Easier for developers to maintain libraries and large applications
• Improve the security of the JDK by limiting which packages were exposed
• Improve application performance by reducing the size and surface area of java components
• Enable the JDK to better scale for use in small devices and cloud deployments