install java 11 jdk raspberry pi
sudo update-alternatives --install /usr/bin/java java /opt/jdk/zulu11.31.16-ca-jdk11.0.3-linux_aarch32hf/bin/java 1
sudo update-alternatives --install /usr/bin/javac javac /opt/jdk/zulu11.31.16-ca-jdk11.0.3-linux_aarch32hf/bin/javac 1