Install ADT Eclipse "You are installing software that contains unsigned content"

Question

I am a newbie in Ubuntu. I want install ADT (Android Development Tools) Eclipse, but there is a popup like this:

Please someone help me to solve my problem.

Answer 1

This is expected, and explained in ADT site:

9. Read and accept the license agreements, then click Finish.

   If you get a security warning saying that the authenticity or validity of the software can't be established, click OK.

Many Eclipse plugins are unsigned, and this is just one of them. (See also a similar question in Stack Overflow)