I am MAC OS X Yosemite I have done all the export tutorial to set the android_home but non of it working for me
Make sure the env variable you exported is ANDROID_HOME and not android_home (case sensitive).
After you export, test it by typing
> echo $ANDROID_HOME
The result should point to the dir where you installed the SDK.
Last but not least edit your /etc/paths to add dirs $ANDROID_HOME/platform-tools or /Users/abdi/adt/sdk/platform-tools and $ANDROID_HOME/tools or /Users/abdi/adt/sdk/tools to the list. Save file. You might need to edit this file as admin if need be. Close terminal and then Open new terminal. Then type
> echo $PATH
to check if the path is updated.
And then voila, when you type
> which android
you should see the correct path to the binary returned which in your case is /Users/abdi/adt/sdk/tools/android. you should be all set now.