Java Version Checker
This practical mod timely warns players about using outdated Java versions. The modification elegantly displays a clear message if it detects old Java, helping to avoid mod compatibility issues.
The program offers two checking options - for Java 7 and Java 8. The choice of specific version depends on your needs.

Simple Installation First make sure you have compatible Forge version installed. Then download the universal build of Java Version Checker and place the file in the mods folder. This method works for all Minecraft versions starting from 1.6.2.
Special Usage Scenarios If you need to integrate Java checking into another mod, check out the guide on including Java Checker in the project's GitHub repository. For Minecraft 1.6.1 and older versions, Java Checker v1.1 is required, which is installed into the coremods folder.
Including the mod in modpacks is welcome. Source code is available for study and modification.
Video demonstration of mod capabilities: Author's YouTube channel