export JAVA_HOME=/usr/share/jdk-13.0.1
export PATH=$PATH:$JAVA_HOME/bin
export CLASSPATH=:$JAVA_HOME/lib/dt.jar:$JAVA_HOME/lib/tools.jar
export PATH=$JAVA_HOME/bin:$JRE_HOME/bin:$PATH
openjdk website to download openjdk and then add the code above into your /etc/profile
then source /etc/profile to enable