Extends Android APIs

I work with Eclipse and implement some applications using the Android Emulator.

I'd like to know:

1. is it possible to extend Android APIs 开发者_JAVA百科with other .jar file?
2. If it's possible, how can I extend the APIs? I just have to add libraries to the project or do I copy it to the $ANDROID_HOME/platforms/android-8/tools/lib

If you want to use thirdparty jars you just need to include them in your Android application. You can do that putting them in a lib directory under your android project or adding them to your build path. You do not need to add anything to the SDK.