Windows batch & java: Combining -XX:OnOutOfMemoryError command and batch parameters

Question

I am completely new to Windows batch programming. What I want to achieve is to write a startup script for a Java application. Yet, it does not start the Java application, but rather prints out

Usage: java [-options] class [args...]

(to execute a class)

or java [-options] -jar jarfile [args...]

(to execute a jar file)

...

which indicates that my parameters are not correctly recognized.

---

Here is my MCVE for the not-working script:

set memory=600000
java -XX:OnOutOfMemoryError="taskkill /PID %p" -Xmx%memory%K -jar MyApp.jar

In the real scenario, memory is calculated to set the optimal maximal heap size for the application.

---

Leaving out one of both parameters makes the app start. So

java -XX:OnOutOfMemoryError="taskkill /PID %p" -jar MyApp.jar

and

set memory=600000
java -Xmx%memory%K -jar MyApp.jar

works, but I need both parameters to work in one call.

Answer 1

If you put @echo on and @echo off in your script you can see what command is actually being executed.

You say that the resulting command is:

java -XX:OnOutOfMemoryError="taskkill /PID memoryK -jar MyApp.jar

which makes it look like the % of %p is being considered an "opening" % for the substitution.

Aside from the quotes not being balanced, this means that you are effectively not giving java a command to run - the -jar MyApp.jar is actually inside the -XX:OnOutOfMemoryError string.

Try replacing the single % with %% - according to this question, that is how to write a literal % in a BAT file:

java -XX:OnOutOfMemoryError="taskkill /PID %%p" -Xmx%memory%K -jar MyApp.jar