Java pre-installed in Windows and Linux?

I know that Java is pre-installed in Mac OS X but i wonder if it is pre-installed in Windows XP, Vista, 7 and all Linux dis开发者_JS百科tros?

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Java isn't preinstalled in any Windows version (OEM not included - depends on the manufacturer then).

I think it is not common in Linux distributions at all, but I don't want to make a general statement about ALL distros here ;-)

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Fedora Linux comes with IcedTea, an open source Java.

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Some Linux versions I experienced comes with old versions of Java JDK (so you must take care developing for these distributions!) or with an alternative version of the compiler: Gnu Compiler Java (GCJ).

About the virtual machine, I've just seen the JVM in Windows and Linux, provided by Sun.

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I understand that the vast majority of PCs come with the Sun JRE installed. There was a bit of a law suite between Microsoft and Sun (my employer, now a wholly owned subsidiary of Oracle).

The "6-open" OpenJDK is a backport of the GPLed JDK7. General purpose distros should include it, but of course with Linux you are fighting with package management.