How about a smaller JRE so that it could be bundled with your Java application? If you thought that this not possible then you need to read this. Here comes the first Java SE implementation dubbed as Excelsior JET 5.0 which lets developers leave the unused part of the platform out of their application installer and at the same time ensures that full java compatibility is maintained through on demand downloading of the omitted at runtime.

Thousands of standard API classes and a number of method libraries and data files are included in Java SE implementation but a number of APIs are not used at all therefore Excelsior JET 5.0 leaves out certain portions of Java SE platform from the installation package bringing down the download size and disk footprint. Since Java SE is a monolithic platform a question might come to your mind as to how a licensed Java SE implementation could allow removing parts of the platform and still remain compatible? The solution is that when an installer is built for optimizing application a secondary package containing detached Java SE components is built automatically. The package is placed on a web server accessible to end users and in case an application attempts to access the detached components the secondary package will be downloaded and unpacked during runtime.