Fix sdkmanager java.lang.NoClassDefFoundError batchfile
You can try this solution
First open sdkmanager.bat
with any text editor
Then find this line
%JAVA_EXE%" %DEFAULT_JVM_OPTS% %JAVA_OPTS% %SDKMANAGER_OPTS%
And change it to this line
%JAVA_EXE%" %DEFAULT_JVM_OPTS% --add-modules java.xml.bind %JAVA_OPTS% %SDKMANAGER_OPTS%
I hope this solves your problem.
I had the issue as default installation of java was v11
java -version
Should be : openjdk version "1.8.0_252"
Fix:sudo apt-get install openjdk-8-jdk
Don't worry won't overwrite
Then switch to the correct version viasudo update-alternatives --config java
confirm correct output from java -version
than run sdkmanager
again.