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What does the "-D" parameter means?

Sara El-Kady

Joined: Jan 11, 2010
Posts: 14
Hi all,

This might sound pretty basic but I would like to understand what does the "-D" paramenter mean in the following line?

is there some sort of documentation that has all the other valid paramenters as well?

Jeanne Boyarsky
author & internet detective

Joined: May 26, 2003
Posts: 32088

-D is Java's way of saying "system property." It is to show the argument goes to the VM rather than the main() method of your program.

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Tim Holloway
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Joined: Jun 25, 2001
Posts: 16753

To expand, "D" for "Define", so "-Dname=value" constructs a name/value pair and catalogs the name in the JVM's System Properties collection. This collection is convenient as a quick-and-dirty command-line option facility (since you don't have to parse it yourself), as the place to set environment features of the JVM itself, and as a way to support options to "add-in" systems which the application doesn't need to configure itself. Things like logging options, for example.

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subject: What does the "-D" parameter means?