When I try to run this:

sudo apt-get install groovy 

I get this big error:

Setting up oracle-java7-installer (7u3-0~eugenesan~precise4) ...

Downloading...

--2012-04-28 18:43:39--  http://download.oracle.com/otn-pub/java/jdk/7u3-b04/jdk-7u3-linux-i586.tar.gz

Resolving download.oracle.com (download.oracle.com)... 96.17.181.40, 96.17.181.49

Connecting to download.oracle.com (download.oracle.com)|96.17.181.40|:80... connected.

HTTP request sent, awaiting response... 302 Moved Temporarily

Location: https://edelivery.oracle.com/otn-pub/java/jdk/7u3-b04/jdk-7u3-linux-i586.tar.gz [following]

--2012-04-28 18:43:39--  https://edelivery.oracle.com/otn-pub/java/jdk/7u3-b04/jdk-7u3-linux-i586.tar.gz

Resolving edelivery.oracle.com (edelivery.oracle.com)... 184.50.22.174

Connecting to edelivery.oracle.com (edelivery.oracle.com)|184.50.22.174|:443... connected.

HTTP request sent, awaiting response... 302 Moved Temporarily

Location: http://download.oracle.com/errors/download-fail-1505220.html [following]

--2012-04-28 18:43:40--  http://download.oracle.com/errors/download-fail-1505220.html

Connecting to download.oracle.com (download.oracle.com)|96.17.181.40|:80... connected.

HTTP request sent, awaiting response... 200 OK

Length: 5307 (5.2K) [text/html]

Saving to: `./jdk-7u3-linux-i586.tar.gz'



     0K .....                                                 100% 47.2K=0.1s



2012-04-28 18:43:40 (47.2 KB/s) - `./jdk-7u3-linux-i586.tar.gz' saved [5307/5307]



Download done.

sha256sum mismatch jdk-7u3-linux-i586.tar.gz

Oracle JDK 7 is NOT installed.

dpkg: error processing oracle-java7-installer (--configure):

 subprocess installed post-installation script returned error exit status 1

dpkg: dependency problems prevent configuration of groovy:

 groovy depends on default-jre-headless | sun-java6-jre; however:

  Package default-jre-headless is not installed.

  Package oracle-java7-installer which provides default-jre-headless is not configured yet.

  Package sun-java6-jre is not installed.

dpkg: error processing groovy (--configure):

 dependency problems - leaving unconfigured

No apport report written because the error message indicates its a followup error from a previous failure.

                          Errors were encountered while processing:

 oracle-java7-installer

 groovy

E: Sub-process /usr/bin/dpkg returned an error code (1)

I already have Java installed in my PC. When I run :

java -version

I get:

java version "1.7.0_04"

Java(TM) SE Runtime Environment (build 1.7.0_04-b20)

Java HotSpot(TM) Server VM (build 23.0-b21, mixed mode)

Where am I making a mistake?

Thanks in advance.