It is true, however, that the VM on each platform can and usually does implement features to specifically suit the uses it is likely to be put to. A clear example of this would be mobile-device-specific features such as sensors, GPS, or the built-in camera on many Android devices. Using Java with Android, you can take photos, detect the air pressure, and work out exactly where in the world you are. Most fridge VMs probably will not do this. So you can't always just run a Java program designed for device x on device y, but the language and syntax is the same. Learning Java on Android prepares you in a large part for Java in any situation. So rest assured that Java isn't going away any time soon