Installing Java

Although SDKMAN! and even apt allow to install a JDK, I prefer to do it manually.

1. Download the install package from the Eclipse Temurin Download page.

   Select the latest LTS version of the JDK that fits for the target operation system.

   Target	Architecture
   Ubuntu on Desktop/Laptop	x64
   MacOS on Intel	x64
   MacOS on A#	aarch64
   Windows	x64
   Raspberry Pi OS 64bit	aarch64
   Raspberry Pi OS 32bit	arm

   Perhaps some versions are not available for all targets.

   The following steps are for Linux operating systems; for Windows, you usually just starts the installer (*.msi) for the JDK.

2. Create the target folder:

   cd /opt
   sudo mkdir java
   

3. Install the JDK in the target folder; if the downloaded file from the first step was stored in the Downloads folder, the command would be like this:

   cd /opt/java
   sudo tar -xvf ~/Downloads/OpenJDK….tar.gz
   

   Of course the correct name for the file must be provided.

4. Create the shell script SetupJava.sh somewhere on the local PATH (usually ~/bin or ~/.local/bin).

   The contents of the file looks like this:

   #! /bin/sh
   JAVA_PATH="/opt/java/<install_path>/bin"
   
   sudo update-alternatives --install "/usr/bin/jar" "jar" $JAVA_PATH/jar 1 
   sudo update-alternatives --set "jar" $JAVA_PATH/jar 
   
   sudo update-alternatives --install "/usr/bin/jarsigner" "jarsigner" $JAVA_PATH/jarsigner 1 
   sudo update-alternatives --set "jarsigner" $JAVA_PATH/jarsigner 
   
   sudo update-alternatives --install "/usr/bin/java" "java" $JAVA_PATH/java 1
   sudo update-alternatives --set "java" $JAVA_PATH/java
   
   sudo update-alternatives --install "/usr/bin/javac" "javac" $JAVA_PATH/javac 1
   sudo update-alternatives --set "javac" $JAVA_PATH/javac
   
   sudo update-alternatives --install "/usr/bin/javadoc" "javadoc" $JAVA_PATH/javadoc 1
   sudo update-alternatives --set "javadoc" $JAVA_PATH/javadoc
   
   sudo update-alternatives --install "/usr/bin/javap" "javap" $JAVA_PATH/javap 1
   sudo update-alternatives --set "javap" $JAVA_PATH/javap
   
   sudo update-alternatives --install "/usr/bin/jcmd" "jcmd" $JAVA_PATH/jcmd 1 
   sudo update-alternatives --set "jcmd" $JAVA_PATH/jcmd
        
   sudo update-alternatives --install "/usr/bin/jconsole" "jconsole" $JAVA_PATH/jconsole 1 
   sudo update-alternatives --set "jconsole" $JAVA_PATH/jconsole
   
   sudo update-alternatives --install "/usr/bin/jdb" "jdb" $JAVA_PATH/jdb 1 
   sudo update-alternatives --set "jdb" $JAVA_PATH/jdb
   
   sudo update-alternatives --install "/usr/bin/jdeprscan" "jdeprscan" $JAVA_PATH/jdeprscan 1 
   sudo update-alternatives --set "jdeprscan" $JAVA_PATH/jdeprscan
   
   sudo update-alternatives --install "/usr/bin/jdeps" "jdeps" $JAVA_PATH/jdeps 1 
   sudo update-alternatives --set "jdeps" $JAVA_PATH/jdeps
   
   sudo update-alternatives --install "/usr/bin/jfr" "jfr" $JAVA_PATH/jfr 1 
   sudo update-alternatives --set "jfr" $JAVA_PATH/jfr
   
   sudo update-alternatives --install "/usr/bin/jhsdb" "jhsdb" $JAVA_PATH/jhsdb 1 
   sudo update-alternatives --set "jhsdb" $JAVA_PATH/jhsdb
   
   sudo update-alternatives --install "/usr/bin/jinfo" "jinfo" $JAVA_PATH/jinfo 1 
   sudo update-alternatives --set "jinfo" $JAVA_PATH/jinfo
   
   sudo update-alternatives --install "/usr/bin/jlink" "jlink" $JAVA_PATH/jlink 1 
   sudo update-alternatives --set "jlink" $JAVA_PATH/jlink
   
   sudo update-alternatives --install "/usr/bin/jmap" "jmap" $JAVA_PATH/jmap 1 
   sudo update-alternatives --set "jmap" $JAVA_PATH/jmap
   
   sudo update-alternatives --install "/usr/bin/jmod" "jmod" $JAVA_PATH/jmod 1 
   sudo update-alternatives --set "jmod" $JAVA_PATH/jmod
   
   sudo update-alternatives --install "/usr/bin/jpackage" "jpackage" $JAVA_PATH/jpackage 1 
   sudo update-alternatives --set "jpackage" $JAVA_PATH/jpackage
   
   sudo update-alternatives --install "/usr/bin/jrunscript" "jrunscript" $JAVA_PATH/jrunscript 1 
   sudo update-alternatives --set "jrunscript" $JAVA_PATH/jrunscript
   
   sudo update-alternatives --install "/usr/bin/jshell" "jshell" $JAVA_PATH/jshell 1 
   sudo update-alternatives --set "jshell" $JAVA_PATH/jshell
   
   sudo update-alternatives --install "/usr/bin/jstack" "jstack" $JAVA_PATH/jstack 1 
   sudo update-alternatives --set "jstack" $JAVA_PATH/jstack
        
   sudo update-alternatives --install "/usr/bin/jstat" "jstat" $JAVA_PATH/jstat 1 
   sudo update-alternatives --set "jstat" $JAVA_PATH/jstat
   
   sudo update-alternatives --install "/usr/bin/jstatd" "jstatd" $JAVA_PATH/jstatd 1 
   sudo update-alternatives --set "jstatd" $JAVA_PATH/jstatd
   
   sudo update-alternatives --install "/usr/bin/jwebserver" "jwebserver" $JAVA_PATH/jwebserver 1 
   sudo update-alternatives --set "jwebserver" $JAVA_PATH/jwebserver
   
   sudo update-alternatives --install "/usr/bin/keytool" "keytool" $JAVA_PATH/keytool 1 
   sudo update-alternatives --set "keytool" $JAVA_PATH/keytool
   
   sudo update-alternatives --install "/usr/bin/rmiregistry" "rmiregistry" $JAVA_PATH/rmiregistry 1 
   sudo update-alternatives --set "rmiregistry" $JAVA_PATH/rmiregistry
   
   sudo update-alternatives --install "/usr/bin/serialver" "serialver" $JAVA_PATH/serialver 1 
   sudo update-alternatives --set "serialver" $JAVA_PATH/serialver
   

   Set the respective installation path and save the script. For future versions of the JDK, additional tools could be added and would require additional entries to the script. Of course, other tools may get dropped from the JDK, and the respective lines need to be removed.

5. Make the script executable and run it:

   chmod u+x SetupJava.sh
   SetupJava.sh
   

This page describes how jshell can be configured to run integrated into the Ubuntu terminal.