Class JavaLaunchHelper is implemented in both ... libinstrument.dylib. One of the two will be used. Which one is undefined

Question

⚠️ For JetBrains IntelliJ IDEA: Go to Help -> Edit Custom Properties.... Create the file if it asks you to create it. To disable the error message paste the following to the file you created:

idea_rt
idea.no.launcher=true

This will take effect on the restart of the IntelliJ.

As of October 2017, this issue is now resolved in

• jdk1.9
• jdk1.8.152
• jdk1.7.161

1. Install Java 7u21 from: http://www.oracle.com/technetwork/java/javase/downloads/java-archive-downloads-javase7-521261.html#jdk-7u21-oth-JPR

2. Set these variables:

   export JAVA_HOME=/Library/Java/JavaVirtualMachines/jdk1.7.0_21.jdk/Contents/Home
   export PATH=$JAVA_HOME/bin:$PATH
   

3. Run your app and have fun :)

Copy Pasting @Lichtamberg's comments to gotoalberto's answer

Works also for Java 1.8:

# in ~/.zshrc and ~/.bashrc

export JAVA_HOME=/Library/Java/JavaVirtualMachines/jdk1.8.0_92.jdk/Contents/Home 
export PATH=$JAVA_HOME/bin:$PATH 

This fixed my issue on java 8.

Not sure if this is the cause of the problem, but I got this issue only after installing JVM Monitor.

Uninstalling JVM Monitor solved the issue for me.

As other answers detail, this is a bug in the JDK (up to u45) which will be fixed in JDK7u60 - while this is not out yet, you may download the b01 from: https://jdk7.java.net/download.html

It's beta, but fixed that issue for me.

https://groups.google.com/forum/#!topic/google-appengine-stackoverflow/QZGJg2tlfA4

From what I've found online, this is a bug introduced in JDK 1.7.0_45. I've read it will be fixed in the next release of Java, but it's not out yet. Supposedly, it was fixed in 1.7.0_60b01, but I can't find where to download it and 1.7.0_60b02 re-introduces the bug.

I managed to get around the problem by reverting back to JDK 1.7.0_25. Probably not the solution you wanted, but it's the only way I've been able to get it working. Don't forget add JDK 1.7.0_25 in Eclipse after installing the JDK.

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