kali安装jdk
sudo update-alternatives --install "/usr/bin/java" "java" "/opt/jdk-14.0.2/bin/java" 1
sudo update-alternatives --install "/usr/bin/javac" "javac" "/opt/jdk-14.0.2/bin/javac" 1
update-alternatives --set java /opt/jdk-14.0.2/bin/java
update-alternatives --set javac /opt/jdk-14.0.2/bin/javac