how to set openjdk as default code example

Example 1: set default java version

# on linux
sudo update-alternatives --config java
# then just input the number of the jdk you
# want to use as default and hit Enter

Example 2: linux change java

sudo update-java-alternatives -s java-8-oracle
export JAVA_HOME=/usr/lib/jvm/java-8-oracle/
export PATH=$PATH:$JAVA_HOME
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