How to resolve different signature error

I got Calculator source code from google's android.git.kernel.org and successfully build the project without problem. But when I launch it in eclipse, I got this

Re-installation failed due to different application signatures.
[2011-08-14 03:37:04 - JvCalculator] You must perform a full uninstall of the application.     WARNING: This will remove the application data! 
[2011-08-14 03:37:04 - JvCalculator] Please execute 'adb uninstall com.android.calculator2' in a shell.
[2011-08-14 03:37:04 - JvCalculator] Launch canceled!

I don't think I have the application in my emulator. So it's not uninstall/install problem, I think. I suspect that the google's source code has different signature. If so how I can change it? Is there anybody that resolved th开发者_开发技巧is issue? Or do I have to build a new project with copy and paste?

Note that when I tried following while connecting emulator,

adb uninstall com.android.calculator2 

I got a simple one-word error message "Failure".

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"How can I install Calculator (or any app) from the git repository (or from source) to any device that already has it installed?" You can't change the signature because that is a closely guarded secret at Google or (any other app developer). What you can do is change the application's package, with a different package the system will think its a different app.

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I had this exact problem. Uninstalling via adb did the trick:

    adb -d uninstall org.janeullah.android.healthrecords

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1. Try making a new emulator.
2. Try cleaning the project.

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Had same error, but I was testing the app on a device that had the app already installed (some old version). After uninstalling it worked without renaming the packages or other changes.