Ubuntu 12.04 64bit Android source code download problem

Question

I am having AMD Athlon machine with OS Ubuntu 12.04 (64bit OS) installed on it. I need to download source code for android for which I need to follow number of steps as shown in the link. http://source.android.com/source/initializing.html

While following this I need to run the command as

sudo apt-get install git-core gnupg flex bison gperf build-essential \
zip curl libc6-dev libncurses5-dev:i386 x11proto-core-dev \
libx11-dev:i386 libreadline6-dev:i386 libgl1-mesa-glx:i386 \
libgl1-mesa-dev g++-multilib mingw32 openjdk-6-jdk tofrodos \
python-markdown libxml2-utils xsltproc zlib1g-dev:i386

so at a single go this command fails somehow. so I had breaked it down and tried to install. Still I am facing problem when I run the following command:

sudo apt-get install build-essential libc6-dev libncurses5-dev:i386 libreadline6-dev:i386 g++-multilib zlib1g-dev:i386 libxext-dev:i386

the log that get printed in the terminal is as below:

> Reading package lists... Done
Building dependency tree       
Reading state information... Done
Package build-essential is not available, but is referred to by another package.
This may mean that the package is missing, has been obsoleted, or
is only available from another source

Package libc6-dev is not available, but is referred to by another package.
This may mean that the package is missing, has been obsoleted, or
is only available from another source
However the following packages replace it:
  linux-libc-dev:i386 libc-dev-bin

Package libncurses5-dev is not available, but is referred to by another package.
This may mean that the package is missing, has been obsoleted, or
is only available from another source
However the following packages replace it:
  libtinfo-dev

E: Package 'build-essential' has no installation candidate
E: Package 'libc6-dev' has no installation candidate
E: Package 'libncurses5-dev' has no installation candidate
E: Unable to locate package g++-multilib
E: Couldn't find any package by regex 'g++-multilib'
E: Unable to locate package zlib1g-dev

Please help on. How I get this solved?

Answer 1

Run:

sudo apt-get update

This will refresh your repositories and could&should solve your problem.

Answer 2

Run the following command:

sudo apt-get install git-core gnupg flex bison gperf build-essential \
zip curl zlib1g-dev libc6-dev lib64ncurses5-dev \
x11proto-core-dev libx11-dev lib64readline5-dev lib64z-dev \
libgl1-mesa-dev g++-multilib tofrodos