Install Java 1.7 non-interatively on Ubuntu 12.04

Question

I need to install Java 1.7 on several machines and hence I want to do it using a script. The problem is the installation asks for certain options (to be specific 'Y', then 'OK' and finally 'Yes'). I came across this question:

Automate the installation of postfix on Ubuntu

I am pretty sure the process is on the same lines. But I don't know how did the OP know about the variable names (?) like postfix postfix/mailname etc.

If someone can provide a more direct answer, it will be most appreciated.

EDIT 1:

I tried setting sudo dpkg-reconfigure debconf to non-interactive and selecting alert level as critial. Then I tried to execute sudo apt-get install oracle-java7-installer and got this error:

Need to get 0 B/18.6 kB of archives.
After this operation, 193 kB of additional disk space will be used.
Preconfiguring packages ...
(Reading database ... 47992 files and directories currently installed.)
Unpacking oracle-java7-installer (from .../oracle-java7-installer_7u51-0~webupd8~4_all.deb) ...

oracle-license-v1-1 license could not be presented
try 'dpkg-reconfigure debconf' to select a frontend other than noninteractive

dpkg: error processing /var/cache/apt/archives/oracle-java7-installer_7u51-0~webupd8~4_all.deb (--unpack):
 subprocess new pre-installation script returned error exit status 2
Errors were encountered while processing:
 /var/cache/apt/archives/oracle-java7-installer_7u51-0~webupd8~4_all.deb
E: Sub-process /usr/bin/dpkg returned an error code (1)

Answer 1

Presumably the same as with Java 8:

echo debconf shared/accepted-oracle-license-v1-1 select true | \
  sudo debconf-set-selections
echo debconf shared/accepted-oracle-license-v1-1 seen true | \
  sudo debconf-set-selections

apt-get -y install oracle-java7-installer oracle-java7-set-default

Answer 2

apt-get install -y --force-yes oracle-java7-installer should do the trick