Set Java version to Oracle Java

Here it is. first install JDK or JRE from oracle download page.
Then use these commands:

 /usr/sbin/alternatives --install "/usr/bin/java" "java" "/usr/java/default/bin/java" 2 \  
 --slave /usr/bin/javac javac /usr/java/default/bin/javac \  
 --slave /usr/bin/javadoc javadoc /usr/java/default/bin/javadoc \  
 --slave /usr/bin/jar jar /usr/java/default/bin/jar \  
 --slave /usr/bin/keytool keytool /usr/java/default/bin/keytool \  
 --slave /usr/bin/orbd orbd /usr/java/default/bin/orbd \  
 --slave /usr/bin/pack200 pack200 /usr/java/default/bin/pack200 \  
 --slave /usr/bin/rmid rmid /usr/java/default/bin/rmid \  
 --slave /usr/bin/rmiregistry rmiregistry /usr/java/default/bin/rmiregistry \  
 --slave /usr/bin/servertool servertool /usr/java/default/bin/servertool \  
 --slave /usr/bin/tnameserv tnameserv /usr/java/default/bin/tnameserv \  
 --slave /usr/bin/unpack200 unpack200 /usr/java/default/bin/unpack200  

Then activate the configuration:

 /usr/sbin/alternatives --config java