What causes the repeated popup? after installing yosemite
There is a stub executable for Java. This is what it looks like. 



It exists to get you to install a specific version of the framework since Apple doesn't bundle it with their computer. 

Think of this as an "install flash player" message, but for the operating system as opposed to a browser plug in. 

No bug, this is how things are designed. If you see it more than once, then you either are calling programs that want you to install Java or you didn't install the tool completely. 

See http://www.java.com/en/download/help/mac_10_10.xml and the general Mac FAQ at the bottom of the page from the link above.