Re: Unable to execute program using the jar option.

From:
Lew <lew@nospam.lewscanon.com>
Newsgroups:
comp.lang.java.programmer
Date:
Tue, 29 May 2007 15:18:17 -0400
Message-ID:
<qv6dnWFN0OTn4cHbnZ2dnUVZ_sGqnZ2d@comcast.com>
dan wrote:

Oddly I am unable to execute my jar directly (without getting an
exception); however, by specifying the class directly it runs just
fine.

If I had to guess.. it seems that it is related to my 2 system
properties .. it is behaving as if my classpath is being corrupted
when I use the -jar flag.


When run with "-jar", the "java" command ignores any external classpath and
looks only in the JAR manifest for its class paths.

<http://java.sun.com/docs/books/tutorial/deployment/jar/run.html>:

The -jar flag tells the interpreter that the application is packaged in the JAR file format.
You can only specify one JAR file, which must contain all the application-specific code.


and <http://java.sun.com/j2se/1.4.2/docs/tooldocs/findingclasses.html>:

The user class path is specified as ...
The JAR archive specified by the -jar option, which overrides all other values.
If this option is used, all user classes come from the specified archive.

....

A JAR file usually contains a "manifest" -- a file which lists the contents of the JAR.
The manifest can define a JAR-class-path, which further extends the class path
(but only while loading classes from that JAR).


--
Lew

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