Install JDK 7 on CentOS

This tutorial will guide you to install JDK (Java Development Kit) on CentOS 6.5 (also 5,7). Java is open source, platform independent programming language.

Now, we have many different platform and versions of java available, for now we will be installing Java SE(Standard Editions) and below version:

1. OpenJDK7
2. Oracle Java 7

Prerequisites
You are admin or non-admin user with sudo rights.

Uninstall existing JDK versions
You can have multiple version of JDK installed on machine but you can use one at a time.
If you want, you can remove existing installed java on the system using the below steps:

Note: This step is optional.

[code language="text"]
#List all existing jdk
$ rpm -aq | grep -i jdk
java-1.6.0-openjdk-1.6.0.36-1.13.8.1.el6_7.x86_64
java-1.6.0-openjdk-devel-1.6.0.36-1.13.8.1.el6_7.x86_64
java-1.7.0-openjdk-1.7.0.85-2.6.1.3.el6_7.x86_64

# Now, uninstalled all java version as shown below:
sudo yum remove java-1.6.0-openjdk-1.6.0.36-1.13.8.1.el6_7.x86_64
sudo yum remove java-1.7.0-openjdk-1.7.0.85-2.6.1.3.el6_7.x86_64
[/code]

Install OpenJDK7 JDK

To install OpenJDK7 use the below commands:
Note:Rpm package "java-1.7.0-openjdk" will install jre not jdk.

[code language="text"]
$ sudo yum install java-1.7.0-openjdk-devel

Loaded plugins: fastestmirror, refresh-packagekit
Setting up Install Process
Loading mirror speeds from cached hostfile
* base: mirror.supremebytes.com
* epel: mirrors.syringanetworks.net
* extras: mirror.supremebytes.com
* nux-dextop: li.nux.ro
* updates: mirror.supremebytes.com
Resolving Dependencies
--> Running transaction check
---> Package java-1.7.0-openjdk-devel.x86_64 1:1.7.0.85-2.6.1.3.el6_7 will be installed
--> Processing Dependency: java-1.7.0-openjdk = 1:1.7.0.85-2.6.1.3.el6_7 for package: 1:java-1.7.0-openjdk-devel-1.7.0.85-2.6.1.3.el6_7.x86_64
--> Running transaction check
---> Package java-1.7.0-openjdk.x86_64 1:1.7.0.85-2.6.1.3.el6_7 will be installed
--> Finished Dependency Resolution

Dependencies Resolved

================================================================================
Package Arch Version Repository
Size
================================================================================
Installing:
java-1.7.0-openjdk-devel x86_64 1:1.7.0.85-2.6.1.3.el6_7 updates 9.4 M
Installing for dependencies:
java-1.7.0-openjdk x86_64 1:1.7.0.85-2.6.1.3.el6_7 updates 26 M

Transaction Summary
================================================================================
Install 2 Package(s)

Total download size: 35 M
Installed size: 126 M
Is this ok [y/N]: y
Downloading Packages:
(1/2): java-1.7.0-openjdk-1.7.0.85-2.6.1.3.el6_7.x86_64. | 26 MB 00:07
(2/2): java-1.7.0-openjdk-devel-1.7.0.85-2.6.1.3.el6_7.x | 9.4 MB 00:02
--------------------------------------------------------------------------------
Total 3.8 MB/s | 35 MB 00:09
Running rpm_check_debug
Running Transaction Test
Transaction Test Succeeded
Running Transaction
Installing : 1:java-1.7.0-openjdk-1.7.0.85-2.6.1.3.el6_7.x86_64 1/2
Installing : 1:java-1.7.0-openjdk-devel-1.7.0.85-2.6.1.3.el6_7.x86_64 2/2
Verifying : 1:java-1.7.0-openjdk-devel-1.7.0.85-2.6.1.3.el6_7.x86_64 1/2
Verifying : 1:java-1.7.0-openjdk-1.7.0.85-2.6.1.3.el6_7.x86_64 2/2

Installed:
java-1.7.0-openjdk-devel.x86_64 1:1.7.0.85-2.6.1.3.el6_7

Dependency Installed:
java-1.7.0-openjdk.x86_64 1:1.7.0.85-2.6.1.3.el6_7

Complete!
[/code]

Verify the installation using command:

[code language="text"]
$ java -version
java version "1.7.0_85"
OpenJDK Runtime Environment (rhel-2.6.1.3.el6_7-x86_64 u85-b01)
OpenJDK 64-Bit Server VM (build 24.85-b03, mixed mode)
[/code]

Install Oracle JDK 7
To install OracleJDK7 use the below commands

[code language="text"]
#Download the tarball of oracle jdk
$ sudo wget --no-cookies --no-check-certificate --header "Cookie: gpw_e24=http%3A%2F%2Fwww.oracle.com%2F; oraclelicense=accept-securebackup-cookie" "http://download.oracle.com/otn-pub/java/jdk/7u71-b14/jdk-7u71-linux-x64.tar.gz"

# untar the downloaded tarball in /opt/ directory
$ sudo tar xvf jdk-7u71-linux-x64.tar.gz -C /opt/

# change the ownership of untar jdk directory
$ sudo chown -R root: /opt/jdk1.7.0_71

#install jdk
$ sudo alternatives --install /usr/bin/java java /opt/jdk1.7.0_71/bin/java 1
$ sudo alternatives --install /usr/bin/javac javac /opt/jdk1.7.0_71/bin/javac 1
$ sudo alternatives --install /usr/bin/jar jar /opt/jdk1.7.0_71/bin/jar 1
[/code]

Verify the installation using command:

[code language="text"]
$ java -version

java version "1.7.0_71"
Java(TM) SE Runtime Environment (build 1.7.0_71-b14)
Java HotSpot(TM) 64-Bit Server VM (build 24.71-b01, mixed mode)
[/code]

Configure Environment Variable
Below are steps to configure java variables

[code language="text"]
$ sudo vi /etc/profile.d/java.sh

#Add the below line shell script "java.sh"

#If Oracle JDK 7 install
export JAVA_HOME=/opt/jdk1.7.0_71
# use below JAVA_HOME if OpenJDK7devel install
#export JAVA_HOME=/usr/lib/jvm/java-openjdk
export JAVA_PATH=$JAVA_HOME
export PATH=$PATH:$JAVA_HOME/bin
[/code]

Again log in the machine or use below to see the changes
[code language="text"]
$ source .bashrc
$ echo $JAVA_HOME
[/code]

References:
https://en.wikipedia.org/wiki/Java_(software_platform)
http://docs.oracle.com/javase/7/docs/webnotes/install/
http://openjdk.java.net/projects/jdk7/