change-java-version.sh

change-java-version.sh

#!/bin/bash

# License: Eclipse Public License - v 2.0 (https://www.eclipse.org/org/documents/epl-2.0/EPL-2.0.html)
# Updated on November 7, 2022

if [[ "$EUID" -ne 0 ]]
then
  echo -e "\nThis script must be run as root. Exiting. . . .\n\n"
  exit 1
fi

if [ -z "$1" ]
then
  echo -e "\nOne must pass the Java version to enable. Exiting. . . .\n\n"
  exit 1
fi

# Check for integer parameter
if ! [[ "$1" =~ ^[0-9]+$ ]]
then
  echo -e "\nOne must pass a valid number like 8 or 11 Exiting. . . .\n\n"
  exit 1
fi

lcVersion="$1"

echo -e "=> --------------------------------------"
echo -e "=> apt remove --purge openjdk* java-common default-jdk -y"
echo -e "=> --------------------------------------\n"
sudo apt remove --purge openjdk* java-common default-jdk -y

echo -e "=> --------------------------------------"
echo -e "=> apt autoremove --purge -y"
echo -e "=> --------------------------------------\n"
sudo apt autoremove --purge -y

echo -e "=> --------------------------------------"
echo -e "=> update-alternatives --config java"
echo -e "=> --------------------------------------\n"
sudo update-alternatives --config java

echo -e "=> --------------------------------------"
echo -e "=> apt install openjdk-${lcVersion}-jdk -i"
echo -e "=> --------------------------------------\n"
sudo apt install "openjdk-${lcVersion}-jdk" -y

echo -e "=> --------------------------------------"
echo "=> Java Version Info"
echo -e "=> --------------------------------------\n"
java -version

if [ -z "${JAVA_HOME:-}" ]
then
  echo -e "\nJAVA_HOME has not been set, and that's probably okay.\n\n"
else
  lcJavaHome="${JAVA_HOME}"
  if [ ! -d "${lcJavaHome}" ]
  then
    echo -e "\nThe folder referenced by JAVA_HOME, ${lcJavaHome}, does not exist.\n"
  else
    echo -e "\nJAVA_HOME is set to an existing installation of Java: ${lcJavaHome}.\n"
  fi
fi

echo -e "=> --------------------------------------"
echo "=> Saving Java Version ${lcVersion} Certificates"
echo -e "=> --------------------------------------\n"

# The below fixes problems with running maven with Java versions greater than 8. You'll get
# 'trustAnchors parameter must be non-empty' error messages as discussed here:
# https://stackoverflow.com/questions/39788295/maven-error-repeated-java-security-invalidalgorithmparameterexception-the-tr
# Here's a good explanation of the problem when running in Ubuntu
# https://bugs.launchpad.net/ubuntu/+source/ca-certificates-java/+bug/1739631

lcCerts="cacerts"
lcCertTopDir="/etc/ssl/certs/"
lcCertDirOriginal="${lcCertTopDir}java/"
lcCertDirSave="${lcCertTopDir}java.${lcVersion}/"

lcCertDirGet8="${lcCertTopDir}java.8/"

if [ ! -d "${lcCertDirSave}" ]
then
  mkdir -p "${lcCertDirSave}"
fi

sudo cp "${lcCertDirOriginal}${lcCerts}" "${lcCertDirSave}${lcCerts}"

if [ "${lcVersion}" != "8" ]
then
  echo -e "=> --------------------------------------"
  echo "=> Retrieving Java Version 8 Certificates"
  echo -e "=> --------------------------------------\n"

  if [ ! -f "${lcCertDirGet8}${lcCerts}" ]
  then
    echo -e "${lcCertDirGet8}${lcCerts} does not exist. You should install Java 8 first, then Java ${lcVersion}"
  else
    echo -e "Running sudo cp ${lcCertDirGet8}${lcCerts} ${lcCertDirOriginal}${lcCerts}"
    sudo cp "${lcCertDirGet8}${lcCerts}" "${lcCertDirOriginal}${lcCerts}"
  fi

fi