java 8 - How select a given JDK in CentOS -

i want update java version in centos machine,

actually when java -version gives me :

$java -version java version "1.7.0_79" openjdk runtime environment (rhel-2.5.5.3.el6_6-x86_64 u79-b14) openjdk 64-bit server vm (build 24.79-b02, mixed mode) 

i'm using alternatives configure java interpreter should used :

 sudo alternatives --config java 

it gives me :

there 3 programs provide 'java'.        selection    command     -----------------------------------------------     *  1           /usr/lib/jvm/jre-1.7.0-openjdk.x86_64/bin/java        2           /usr/lib/jvm/jre-1.6.0-openjdk.x86_64/bin/java      + 3           /usr/lib/jvm/jdk1.8.0_91/bin/java  enter keep current selection[+], or type selection number: 

and selected number 3 (which jdk1.8.0_91)

however when redo java -version still openjdk 1.7 selected !!!

$java -version java version "1.7.0_79" openjdk runtime environment (rhel-2.5.5.3.el6_6-x86_64 u79-b14) openjdk 64-bit server vm (build 24.79-b02, mixed mode) 

run these command check configuration:

• $ java , result should /bin/java or /usr/bin/java. otherwise, check environment profile (/etc/bashrc, /etc/profile, ~/.bash_profile, ~/.bashrc, etc.) , remove similar export java_home="/usr/lib/jvm/java-1.7.0-openjdk-1.7.0.79.x86_64/jre" declared.
• $ ls -al /bin/java or $ ls -al /usr/bin/java should point /etc/alternatives/java or alternatives ineffective.