android installing apk file manually error

I wondered what installing apk files into emulator or device means and tried to install manually wit开发者_JAVA百科h eclipse first. I opened file explorer tab in ddms section in eclipse and realized that all files with apk extension are in app folder. I selected app directory and clicked push a file onto device button on the top. With selecting apk file i want it was installed to the emulator. However, i am getting this error

Is this error about my installation method or caused by something different ?

The only way to install an apk is with

adb install FileName.apk

I think that the installation procedure of an Android application would be more complex than simply putting the apk in the app directory. Various folders have to be created to store application local data, file permissions for the application has to be set, the package manager has to be updated about the new package, and many other scores.

You should really just use the default installer of Android to take care of the installation. And, if you are really curious to know the installation procedure, you can always check out the source code! You can find details in the Getting Started page on how to download the source.