Matlab Running error after fresh installation.

Specs: Matlab R2013a (64-bit) and OS is Ubuntu 15.04 (64-bit).

I have successfully installed and activated the Matlab.

After opening it via terminal, terminal shows this error,

    *Warning* : Unable to load Java Runtime Environment: *libjvm.so* : cannot open shared object file: No such file or directory

    *Warning* : Disabling Java support Warning: latest version of matlab app-defaults file not found. Contact your system administrator to have this file installed.

                        < M A T L A B (R) >
              Copyright 1984-2013 The MathWorks, Inc.
                R2013a (8.1.0.604) 64-bit (glnxa64)
                         February 15, 2013

    Disabling Java support Warning: MATLAB Toolbox Path Cache is out of date and is not being used. Type 'help toolbox_path_cache' for more info

I don't have Java installed on my system. should I install it?

please advise.

EDIT :

Previously I first installed Java 7 and jdk both, but it came out with same error. I thought that there is a mismatch between Java installed and Java resources pre-packaged in Matlab Installation media. So, I did a fresh install of Ubuntu 15.04 (64-bit) and Matlab both. but still the same error on running matlab.