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Message:

RE: A basic Question

Posted by Lee Collins on August 01, 2000 at 12:04 PM

> Why do we need to have different implementations of JVM for different platforms when JVM by Sun can do everything for us??
> I am new to Java

There has to be a JVM for each type of system eg. WindowsNT, Mac, RS6000, etc.

The JVM on a particular system know how to translate the bytecode for THAT system.

The different JVMs are how that you can write the program once and run it anywhere(that has a JVM). The JVM does the actual talking to the Operating System.

For instance, to open a File is differnt on different Operating Systems. To open a file on UNIX you would use the open() function. On NT you would use the OpenFile() function.

The Windows NT JVM will translate a call to open a file into a call to OpenFile() while a JVM for UNIX will translate those same bytecodes into a call to open().

Lee