This is an update to the previous article Switching Java versions.

Here is an improved version of the script, to switch between different java versions. You can put it into your .bashrc.

function switch_java_home {
    echo "-----------------------------"
    echo "Switching Java"
    if [ ! -z "${JAVA_HOME}" ]; then
        echo "Old: $JAVA_HOME";

    echo "JAVA_HOME: ${JAVA_HOME}"
    export JAVA_HOME
    export PATH
    java -version
    echo "-----------------------------"

alias oraclejava6="switch_java_home $HOME/programs/oraclejdk/jdk1.6.0_45"
alias oraclejava7="switch_java_home $HOME/programs/oraclejdk/jdk1.7.0_80"
alias oraclejava8="switch_java_home $HOME/programs/oraclejdk/jdk1.8.0_231"
alias oraclejava9="switch_java_home $HOME/programs/oraclejdk/jdk-9.0.4"
alias oraclejava10="switch_java_home $HOME/programs/oraclejdk/jdk-10.0.2"
alias oraclejava11="switch_java_home $HOME/programs/oraclejdk/jdk-11.0.5"

alias openjdk8="switch_java_home /usr/lib/jvm/java-8-openjdk-amd64"
alias openjdk9="switch_java_home $HOME/programs/openjdk/jdk-9.0.4"
alias openjdk10="switch_java_home $HOME/programs/openjdk/jdk-10.0.2"
alias openjdk11="switch_java_home $HOME/programs/openjdk/jdk-11.0.5+10"
alias openjdk12="switch_java_home $HOME/programs/openjdk/jdk-12.0.2"
alias openjdk13="switch_java_home $HOME/programs/openjdk/jdk-13.0.1+9"


The function switch_java_home does several things: Removing the previous java path from your PATH environment variable, so that it stays clean; adding the new java path; logging out the new java version in the console.

The aliases provide nice shortcuts to your available java installations.

The last command oraclejava13 makes that to your default java version after you opened a shell.

Example for switching between oraclejava11 and openjdk11:

$ oraclejava11
Switching Java
JAVA_HOME: /home/andreas/programs/oraclejdk/jdk-11.0.5
java version "11.0.5" 2019-10-15 LTS
Java(TM) SE Runtime Environment 18.9 (build 11.0.5+10-LTS)
Java HotSpot(TM) 64-Bit Server VM 18.9 (build 11.0.5+10-LTS, mixed mode)
$ openjdk11
Switching Java
Old: /home/andreas/programs/oraclejdk/jdk-11.0.5
JAVA_HOME: /home/andreas/programs/openjdk/jdk-11.0.5+10
openjdk version "11.0.5" 2019-10-15
OpenJDK Runtime Environment AdoptOpenJDK (build 11.0.5+10)
OpenJDK 64-Bit Server VM AdoptOpenJDK (build 11.0.5+10, mixed mode)

With that in place, it’s easy to switch between various java versions.

By the way: As you see, I use the open jdk variant from AdoptOpenJdk.