Java in Java vs Java in PHP - Why?

I let my mind wander a bit today and thought about all the different programming/scripting languages.

It makes sense to me to want the functionality of one piece of code available to another program constructed in a different language.

Opening up language/library bindings is good... though I'm not about to .NET my Python to PHP# quite yet! lol

But I don't understand where people attempt to integrate one langauge into another.

Here's an example of Java in PHP taken from php.net/java:

<?php
Â* // get instance of Java class java.lang.System in PHP
Â* $system = new Java('java.lang.System');

Â* // demonstrate property access
Â* echo 'Java version=' . $system->getProperty('java.version') . '<br />';
Â* echo 'Java vendor=' . $system->getProperty('java.vendor') . '<br />';
Â* echo 'OS=' . $system->getProperty('os.name') . ' ' .
Â*Â* Â* Â* Â* Â* Â* $system->getProperty('os.version') . ' on ' .
Â*Â* Â* Â* Â* Â* Â* $system->getProperty('os.arch') . ' <br />';

Â* // java.util.Date example
Â* $formatter = new Java('java.text.SimpleDateFormat',
Â*Â* Â* Â* Â* Â* Â* Â* Â* Â* Â* Â* "EEEE, MMMM dd, yyyy 'at' h:mm:ss a zzzz");

Â* echo $formatter->format(new Java('java.util.Date'));
?>

I admit there's a certain coolness factor involved, but why not write Java in Java instead of Java in PHP?

Well, in the real world, there are many issues that need to be considered.

Perhaps you have a running website with 25000 lines of PHP, while another department has some Java code you need to integrate into the website, which is another 25000 lines. In this case it's obviously better if you just use the Java extension in PHP instead of either changing the whole site to Java or porting the Java code into PHP.