Javas are benevolent entities. Their heads and bodies are filled with coffee, and the white part on their head prevents the liquid from pouring out in the case that a Java gets flipped over. Without this coffee, Javas will die, as their coffee is to them as what blood is to a human.
In a computer, there is usually only one individual Java. These individuals have many workers called Java Scripters which resemble them, but are smaller than them.