There are several potential reasons, but the first
you should check is whether in the Preferences/Java/Installed JREs the default is a JDK, not just a JRE. (Eclipse needs the source code to know parameter names, and JREs are not shipped with source code.)
The soul is dyed the color of its thoughts. Think only on those things that are in line with your principles and can bear the light of day. The content of your character is your choice. Day by day, what you do is who you become. Your integrity is your destiny - it is the light that guides your way. - Heraclitus