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javalinuxgradlebuild.gradle

gradle build not finding executable at expected location

I am new to gradle. I am getting an warning message when using gradle build:

gradle build
Path for java installation '/usr/lib/jvm/openjdk-11' (Common Linux Locations) does not contain a java executable

BUILD SUCCESSFUL in 399ms
3 actionable tasks: 3 up-to-date

The build is successful, but is this an issue I should fix?

Some info:

  1. usr/lib/jvm/openjdk-11 only contains a src.zip file, nothing else

  2. 'which java' returns /usr/bin/java

  3. namei /usr/bin/java returns

f: /usr/bin/java
 d /
 d usr
 d bin
 l java -> /etc/alternatives/java
   d /
   d etc
   d alternatives
   l java -> /usr/lib/jvm/java-11-openjdk-amd64/bin/java
     d /
     d usr
     d lib
     d jvm
     d java-11-openjdk-amd64
     d bin
     - java

  1. echo $JAVA_HOME returns nothing

  2. echo $PATH returns /usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:/usr/local/games:/snap/bin:/snap/bin:/opt/gradle/gradle-8.4/bin

  3. java -version returns openjdk version "11.0.20.1" 2023-08-24 OpenJDK Runtime Environment (build 11.0.20.1+1-post-Ubuntu-0ubuntu122.04) OpenJDK 64-Bit Server VM (build 11.0.20.1+1-post-Ubuntu-0ubuntu122.04, mixed mode, sharing)

  4. ChatGPT has given me a few erroneous solutions that just lead to the build failing so I won't mention those

Solution

  • These warnings are expected behavior in Gradle (https://github.com/gradle/gradle/issues/22921).

    However, on Ubuntu (and Debian), they do not indicate an actual issue that needs fixing because a src.zip -> lib/src.zip symlink (not an executable) is intentionally placed in /usr/lib/jvm/openjdk-11/ when Java source code is installed with sudo apt install openjdk-11-source (https://askubuntu.com/questions/755853/how-to-install-jdk-sources).

    In other words, Gradle thinks it might be a problem, but it isn't.