I know it’s a hot question that need anwsers ^^
From my viewpoint, using Java vs PHP, is nowadays a problem of system resources (Hardware, Software, etc.).
For Java, you have to deploy J2EE Stack (JDK, AppServer, etc.) (~200M) on your server, for PHP you need to deploy a LAMP system (~100M).
Using Java was in my opinion due to object oriented programming in web application, but today we have a lot of Object Oriented Web Language (Ruby, Python, PHP).
So the question when to choose between Java or PHP for new projects ? Maybe the community difference ?
I know that stackoverflow is not made for discussion, but it’s a (good?) question that need answers (for me and for others maybe) ^^.
Other constraints are usually taken into account. Things like
to name a few.
Hardware and software are cheap if you compare them to the above so they tend to be less important.