How can I fix this error when installing ADT on Ubuntu?

I do not know mu开发者_如何学Pythonch about Eclipse, but according to this tutorial everything should work fine (I am using the .zip archive). The error seems to occur only when Android Development Tools are checked.

Here is the full error code:

Cannot complete the install because one or more required items could not be found.

Software being installed: Android Development Tools 12.0.0.v201106281929-138431 (com.android.ide.eclipse.adt.feature.group 12.0.0.v201106281929-138431)

Missing requirement: Android Development Tools 12.0.0.v201106281929-138431 (com.android.ide.eclipse.adt.feature.group 12.0.0.v201106281929-138431) requires 'org.eclipse.gef 0.0.0' but it could not be found.

I got the answer from the Eclipse forums here

At the available software window, click on the link "Available software sites". You need two items checked, the Android Plugin that you added and the download.eclipse.org/releases/helios or galilio if that is your version of eclipse. Click ok to go back to the available software window. Now select Work with: Android plugin. Now click next continuing with install.

Steps:

1. Help > Install New Software
2. type or paste: http://download.eclipse.org/releases/galileo (change to match your version of eclipse then click Add)
3. Click Cancel, go back to Install New Software and choose the Android related repository. ie. http://dl-ssl.google.com/android/eclipse/)

Note that sometimes you need to use the http, not https link for the ADT repository (the https did not work for me).