Terminating app due to uncaught exception when executing on a Mac where there is no Java

[ampusasidharan]

I'm submitting a bug.

• bug report
• feature request
• other

Short description of the issue/suggestion:
Terminating app due to uncaught exception when executing the app on a Mac where there is no Java (JDK) available.

Steps to reproduce the issue/enhancement:

1. Execute the app on a Mac with no JDK in the system

What is the expected behavior?
Exception should be handled the with a proper error message

What is the current behavior?
It is failing with below uncaught exception

Unable to find any JVMs matching version "(null)".
No Java runtime present, try --request to install.
Print: Entry, ":0:JVMVersion", Does Not Exist
Print: Entry, ":0:JVMHomePath", Does Not Exist
2020-10-19 11:59:32.898 PlistBuddy[75396:4189457] *** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '-[__NSCFArray objectAtIndex:]: index (-1 (or possibly larger)) beyond bounds (0)'
*** First throw call stack:

Do you have screenshots, GIFs, demos or samples which demonstrate the problem or enhancement?
NA

What is the motivation / use case for changing the behavior?
Executing the app on Mac with no Java

Please tell us about your environment:

• universalJavaApplicationStub version: 3.1.0-beta
• Mac OS version: 10.14.6
• Java version(s): No JDK

Other information (e.g. related issues, suggestions how to fix, links for us to have context)

[Flexperte]

It's the for loop on line 579:
# iterate over all Dict entries
for idx in $(seq 0 $((javaCounter - 1)))
do
version=$(/usr/libexec/PlistBuddy -c "print :$idx:JVMVersion" /dev/stdin <<< $javaXml)
path=$(/usr/libexec/PlistBuddy -c "print :$idx:JVMHomePath" /dev/stdin <<< $javaXml)

When javaCounter is 0 then seq 0 -1 makes PlistBuddy run twice with index -1 in the second iteration, when actually the loop should not run at all.

Possible solution:
for (( idx = 0 ; idx < javaCounter ; idx++ ))
But I don't know if that would introduce a typing problem for the compiled version, when $idx is used in a string. I guess that was the reason for writing the loop like this in the first place? So maybe enclosing the whole loop in an "if javaCounter > 0" instead?

[tofi86]

Thanks for the hint @Flexperte! And sorry for the delay @ampusasidharan!

I added a fix with d83b501 which implements a basic if guard.

This will be released shortly with v3.1.1

[tofi86]

I'd be happy to get feedback for this fix. Give it a try by taking the latest version v3.1.1-beta from the develop branch... Otherwise v3.1.1 will be released in a couple of days anyways...