How do I invoke a Java process from Windows Powershell?

Question

I am having trouble running a Java program with Windows Powershell 2.0. Any help on this would be greatly appreciated. I want the string "Hello World!" to print to the main Powershell console window. Instead, its getting printed to a separate process window that opens then suddenly closes. I don't know exactly how to tell the powershell to redirect the stdout of the spawned java process to the current powershell console. Basically, i want behavior just like what I get when running java under a DOS shell.

My test class is:

class HelloWorldApp { 
    public static void main(String[] args) { 
        System.out.println("Hello World!"); //Display the string. 
    } 
}

My PowerShell 2.0 code is this:

set-item -path Env:CLASSPATH -value C:\Test 
"CLASSPATH = $Env:CLASSPATH" 
[Diagnostics.Process]::Start('java.exe','-classpath $Env:CLASSPATH C:\
Test\HelloWorldApp')

Alternatively, I tried to run it like so, as I would with a regular DOS shell, with the hope that the output shows in the same console :

java.exe -classpath $Env:CLASSPATH C:\Test\HelloWorldApp

It causes an error. I get this error:

PS >C:\Test\Test.ps1 
CLASSPATH = C:\Test 
java.exe : java.lang.NoClassDefFoundError: C:\Test\HelloWorldApp 
At C:\Test\Site.ps1:3 char:5 
+ java <<<<  -classpath $Env:CLASSPATH C:\Test\HelloWorldApp 
+ CategoryInfo : NotSpecified: (java.lang.NoCla...e\HelloWorldApp: 
                               String) [], RemoteException 
+ FullyQualifiedErrorId : NativeCommandError 
Exception in thread "main"

As far as I can tell, my args are correct because here is what the PCEX ( http://pscx.codeplex.com ) echoargs cmdlet tells me:

PS >echoargs java.exe -classpath $Env:CLASSPATH C:\Test\HelloWorldApp 
Arg 0 is <java.exe> 
Arg 1 is <-classpath> 
Arg 2 is <C:\Test> 
Arg 3 is <C:\Test\HelloWorldApp>

Im convinced there is a way to get this to work because this code works:

## Test.ps1
cd C:\PSJustice
java.exe -classpath . HelloWorldApp

Also, this works:

cd C:\
java.exe -classpath C:\Test HelloWorldApp

You're getting the NoClassDefFoundError because java.exe expects to be invoked from the directory that the class is in (or the root of the package structure). Don't know about the PowerShell part though. — Michael Myers
– Michael Myers ♦, Commented Jul 1, 2009 at 22:10

djangofan · Accepted Answer · 2009-07-01 23:24:25Z

5

I finally figured it out. It was the smallest typo :

cd c:\
set-item -path Env:CLASSPATH -value C:\Test 
"CLASSPATH = $Env:CLASSPATH" 
java.exe -classpath $Env:CLASSPATH HelloWorldApp

When specifying the Class name it cannot include the absolute path prefixing the class name. Oops.

edited Jul 1, 2009 at 23:24

answered Jul 1, 2009 at 22:35

djangofan

29.9k62 gold badges211 silver badges308 bronze badges

Sign up to request clarification or add additional context in comments.

Collectives™ on Stack Overflow

How do I invoke a Java process from Windows Powershell?

1 Answer 1

Comments

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

Comments

Related