This command used to creates, removes, maintains and displays information about the symbolic links comprising the alternatives system. Let’s use the alternatives command to configure Java on your system.
$ sudo alternatives --config java
There are 2 programs which provide 'java'.
Selection Command
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*+ 1 /usr/lib/jvm/jre-1.7.0-openjdk.x86_64/bin/java
2 /usr/lib/jvm/jre-1.8.0-openjdk.x86_64/bin/java
Enter to keep the current selection[+], or type selection number: 2
