Shell script: running a java application and sending command-line args to it via the script?

Question

This is for a class. I've never used shell scripting before, but the instructions are to write a script that runs my java program (which is already all set up to take in command line arguments (at least one arg, with an optional second one)). I'm supposed to be able to run it like this:

./script.sh arg1 arg2

But when I do, I get the following error (my java main class name is A1):

  Exception in thread "main" java.lang.NoClassDefFoundError: A1/class
  Caused by: java.lang.ClassNotFoundException: A1.class
    at java.net.URLClassLoader$1.run(URLClassLoader.java:202)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.net.URLClassLoader.findClass(URLClassLoader.java:190)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:307)
    at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:301)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:248)
  Could not find the main class: A1.class.  Program will exit.

This is what my shell script looks like right now:

#!/bin/sh

java -Xmx1024m A1.class $@

Any help is appreciated.

Dmitri · Accepted Answer · 2012-02-06 02:09:49Z

3

You need to tell java where to look for your class (using -cp) - either in a directory or a .jar

To find the directory where the script is (as opposed to where it was launched from), you can use: $(dirname $0).

So, for example:

#!/bin/bash

JVM=java
JVM_OPTS="-Xmx1024m"

$JVM $JVM_OPTS -cp $(dirname $0)/myapp.jar A1 "$@"

It's a good idea to be explicit about the shell you want. Also note the quotes around $@, needed for escaped args.

edited Feb 6, 2012 at 2:09

answered Feb 6, 2012 at 1:57

Dmitri

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1 Comment

Tim Over a year ago

Thanks for the help. Turns out all I had to do was get rid of the ".class", but thanks for the tips.

Nicolas Modrzyk · Accepted Answer · 2012-02-06 02:01:17Z

2

Use the classpath flag when running java to tell the virtual machine where your A1.class file is located.

See the doc

Should be something like:

 java -classpath /myfolder A1 $@

Also, do not use the ".class" suffix when running the command.

answered Feb 6, 2012 at 2:01

Nicolas Modrzyk

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1 Comment

Tim Over a year ago

Thank you very much. All I did was get rid of the ".class" and it works.

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