Change to your home directory.
Open the .bashrc file.
Add the following line to the file. Replace the JDK directory with the name of your java installation directory.
export PATH=/usr/java/<JDK Directory>/bin:$PATH
Save the file and exit.
Use the source command to force Linux to reload the .bashrc file which normally is read only when you log in each time.
Note that if you wish to set the PATH for all users, you need to log in as root in the bash shell and perform the above steps on the .profile file in the etc directory and not the .bashrc file in the home directory.