7. Install the Java Development Kit

The correct JDK must be installed on all the nodes in your cluster. To manually deploy the JDK:

Check the version. From a terminal window, type:
```
java -version
```
(Optional) Uninstall the Java package if the JDK version is less than v1.6 update 31.
```
rpm -qa | grep java
yum remove {java-1.*}
```
(Optional) Verify that the default Java package is uninstalled.
```
which java
```

Download the Oracle 64-bit JDK (jdk-6u31-linux-x64.bin) from the Oracle download site:

wget http://www.oracle.com/technetwork/java/javasebusiness/downloads/java-archive-downloads-javase6-419409.html#jdk-6u31-oth-JPR

Change directory to the location where you downloaded the JDK and run the install.

mkdir /usr/jdk1.6.0_31
cd /usr/jdk1.6.0_31
chmod u+x $JDK_download_directory/jdk-6u31-linux-x64.bin
./$JDK_download_directory/jdk-6u31-linux-x64.bin

Create symbolic links (symlinks) to the JDK.

mkdir /usr/java
ln -s /usr/jdk1.6.0_31/jdk1.6.0_31 /usr/java/default
ln -s /usr/java/default/bin/java /usr/bin/java

Set up your environment to define JAVA_HOME to put the Java Virtual Machine and the Java compiler on your path.
```
export JAVA_HOME=/usr/java/default
export PATH=$JAVA_HOME/bin:$PATH
```