The xenial worker in Travis CI comes preinstalled with openjdk8,10,11 according to the doc, however, if you are doing android development and are trying to trying to use sdkmanager eg. (yes | sdkmanager --licenses), you’ll be met with this error message:

Exception in thread "main" java.lang.NoClassDefFoundError: javax/xml/bind/annotation/XmlSchema
	at com.android.repository.api.SchemaModule$SchemaModuleVersion.<init>(SchemaModule.java:156)
	at com.android.repository.api.SchemaModule.<init>(SchemaModule.java:75)
	at com.android.sdklib.repository.AndroidSdkHandler.<clinit>(AndroidSdkHandler.java:81)
	at com.android.sdklib.tool.sdkmanager.SdkManagerCli.main(SdkManagerCli.java:73)
	at com.android.sdklib.tool.sdkmanager.SdkManagerCli.main(SdkManagerCli.java:48)
Caused by: java.lang.ClassNotFoundException: javax.xml.bind.annotation.XmlSchema
	at java.base/jdk.internal.loader.BuiltinClassLoader.loadClass(BuiltinClassLoader.java:583)
	at java.base/jdk.internal.loader.ClassLoaders$AppClassLoader.loadClass(ClassLoaders.java:178)
	at java.base/java.lang.ClassLoader.loadClass(ClassLoader.java:521)
	... 5 more

everywhere you can google, it’ll tell you that you’re using the wrong java version and that you need to downgrade to java 8.

In practice, simply doing a apt-get -y install openjdk-8-jdk won’t fix it since 1. openjdk-8-jdk is already installed and more importantly, 2. the PATH environment variable includes /usr/local/lib/jvm (where Travis has custom installed openjdk10 and openjdk11) ahead of /usr/lib/jvm (where apt-get normally installs java) so you’ll keep getting java11.

My solution was to rm -rf /usr/local/lib/jvm and uninstall any existing java installations and just reinstall what you need. You’ll also need to define JAVA_HOME=/usr/lib/jvm/java-8-openjdk-amd64 for proper sdkmanager operation.

solution:

(.travis.yml snippet)

env:
  global:
  - JAVA_HOME=/usr/lib/jvm/java-8-openjdk-amd64
install:
   - sudo apt-get -y remove default-jdk default-jre default-jdk-headless default-jre-headless ca-certificates-java openjdk-8-jdk openjdk-8-jdk-headless openjdk-8-jre openjdk-8-jre-headless
   - sudo rm -rf /usr/local/lib/jvm
   - sudo apt-get -y update && sudo apt-get -y install openjdk-8-jdk java-common
   - java -version