Using Alternatives

Many Linux distributions use the alternatives command for switching between different versions of a command. You can use this for switching between different versions of Java installed on a machine.

1. In a command shell, set $JDK to the pathname of a newly installed JDK; e.g.

$ JDK=/Data/jdk1.8.0_67

1. Use alternatives --install to add the commands in the Java SDK to alternatives:

$ sudo alternatives --install /usr/bin/java java $JDK/bin/java 2
$ sudo alternatives --install /usr/bin/javac javac $JDK/bin/javac 2
$ sudo alternatives --install /usr/bin/jar jar $JDK/bin/jar 2

And so on.

Now you can switch between different versions of a Java command as follows:

$ sudo alternatives --config javac

There is 1 program that provides 'javac'.

  Selection    Command
-----------------------------------------------
*+ 1           /usr/lib/jvm/java-1.8.0-openjdk-1.8.0.101-1.b14.fc23.x86_64/bin/javac
   2           /Data/jdk1.8.0_67/bin/javac

Enter to keep the current selection[+], or type selection number: 2
$

For more information on using alternatives, refer to the alternatives(8) manual entry.

Arch based installs

Arch Linux based installs come with the command archlinux-java to switch java versions.

Listing installed environments

$ archlinux-java status
Available Java environments:
  java-7-openjdk (default)
  java-8-openjdk/jre

Switching current environment

# archlinux-java set <JAVA_ENV_NAME>

Eg:

# archlinux-java set java-8-openjdk/jre

More information can be found on the Arch Linux Wiki