How to get the Java version in PowerShell

Question

I'm trying to get the Java version in PowerShell. The version string is printed to stderr, so I'm trying to redirect it to stdout and assign it to a string variable.

I get the following strange error:

PS P:\> & java -version 2>&1
java.exe : java version "1.7.0_25"
At line:1 char:2
+ & <<<<  java -version 2>&1
    + CategoryInfo          : NotSpecified: (java version "1.7.0_25":String) [], RemoteException
    + FullyQualifiedErrorId : NativeCommandError

Java(TM) SE Runtime Environment (build 1.7.0_25-b17)
Java HotSpot(TM) 64-Bit Server VM (build 23.25-b01, mixed mode)

Call without redirection (2>&1) gives this:

PS P:\> & java -version
java version "1.7.0_25"
Java(TM) SE Runtime Environment (build 1.7.0_25-b17)
Java HotSpot(TM) 64-Bit Server VM (build 23.25-b01, mixed mode)

I think that Java here is irrelevant, and the same would happen for any other program printing strings to stderr.

The PowerShell version I use is 2.0.

Questions:

• How can I redirect stderr to a variable?
• Or, alternatively, how can I check the installed Java version?

Workaround

I can run it like this:

$output = & cmd /c "java -version 2>&1"

But I hate running a cmd.exe where it shouldn't be necessary.

Solution 1

One way is using WMI:

$javaver =  Get-WmiObject -Class Win32_Product -Filter "Name like 'Java(TM)%'" | Select -Expand Version

Another one is redirect to a file with start-process:

start-process  java  -ArgumentList "-version" -NoNewWindow -RedirectStandardError .\javaver.txt

$javaver = gc .\javaver.txt

del .\javaver.txt

And my last is:

dir "HKLM:\SOFTWARE\JavaSoft\Java Runtime Environment"  | select -expa pschildname -Last 1

Regarding how redirect stderr in this case you can do:

$out = &"java.exe" -version 2>&1
$out[0].tostring()

Solution 2

I have been using Get-Command to get Java version on PowerShell 5.1.

Get-Command java | Select-Object Version

This returns an object. If you want a string instead, use:

(Get-Command java | Select-Object -ExpandProperty Version).toString()

The outputs look like this:

PS > Get-Command java | Select-Object Version

Version
-------
8.0.1710.11



PS > Get-Command java | Select-Object -ExpandProperty Version

Major  Minor  Build  Revision
-----  -----  -----  --------
8      0      1710   11



PS > (Get-Command java | Select-Object -ExpandProperty Version).tostring()
8.0.1710.11

It worked quite well under PowerShell 5.1. I don't have a chance to test this on PowerShell 2.0.

Comments

[Ivan]

Good approach! Didn't work for me just like this (something to do with the -Filter), but has worked as: Get-WmiObject -Class Win32_Product | Where-Object {$_.Name.StartsWith('Java')} | Select -Expand Version

[Ivan]

Thanks. Yes, I knew about -RedirectStandardError option of Start-Process, but hate creating a file just for this simple reason...

[CB.]

@Ivan Added my last ;)

[Ivan]

Amazing! Couldn't think there are so many ways of getting Java version. Will probably use the one with Get-WmiObject. Though it's still not clear how to redirect stderr in PS... but many thanks C.B.!

[CB.]

@Ivan Glad to help! I've added a method for redirect stderr, hope you like it

[Bassie]

The Get-WmiObject approach just causes my script to hang, how annoying

[Ross Presser]

This works great, but be aware that the version will be reported as (e.g.) 8.0.910.14 by this method, whereas java -version reports 1.8.0_91

[Paul Wetter]

Querying the Win32_Product for anything is not recommended. Will cause a system to basically touch every single app installed via msi on a computer.