Viewing the list of Java version installed and selecting the default one

java -version

java version "1.7.0_141"
OpenJDK Runtime Environment (rhel-2.6.10.1.el7_3-x86_64 u141-b02)
OpenJDK 64-Bit Server VM (build 24.141-b02, mixed mode)

sudo update-alternatives --config java

There are 2 programs which provide 'java'.

  Selection    Command
-----------------------------------------------
*+ 1           java-1.7.0-openjdk.x86_64 (/usr/lib/jvm/java-1.7.0-openjdk-1.7.0.141-2.6.10.1.el7_3.x86_64/jre/bin/java)
   2           /usr/java/jdk1.8.0_131/jre/bin/java

java -version

java version "1.8.0_131"
Java(TM) SE Runtime Environment (build 1.8.0_131-b11)
Java HotSpot(TM) 64-Bit Server VM (build 25.131-b11, mixed mode)