Android Studio Error:java: Cannot find JDK '<unknown>' for module 'appcompat_v7'

Question

I have a load of Android Eclipse projects which I need to get working on a new PC (old one broke). Since Eclipse is now deprecated, I have installed Android Studio rather than Eclipse.

Both old and new PC run Ubuntu 14.04LTS, in case it's relevant.

After I import a project, Eclipse tells me "Error:java: Cannot find JDK '' for module 'appcompat_v7'".

I have tried installing Java 6 JDK (jdk1.6.0_45), Java 7 JDK (jdk1.7.0_79) and Java 8 JDK (jdk1.8.0_51) - no change.

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Update: After removing appcompat_v7 as a module, I hit two further problems:

1. I can't add it as a dependency. I don't have a build.gradle, and if I right-click on my app project -> Open Module Settings -> Dependencies -> + -> Library, appcompat_v7 is not there to be selected. SDK Manager reports that I have both Android Support Library and Android Support Repository installed.

...so I removed any reference to appcompat_v7 from my project and tried to run it without...

2. My project now also reports "Error:java: Cannot find JDK '' for module ''" -- just like it did for appcompat_v7.

Answer 1

The best way I found out of this was not to import Eclipse projects into Android Studio at all - I had to do four, and all four of them gave similar problems.

Instead, just create a new Android Studio project and import the code, resources, XMLs and so on. Fortunately all my projects were fairly small so this wasn't too difficult.