目前，我正在使用Android 1.5的HTC Hero，正如我们所知道的，Android 2.2（Froyo）已被发布，所以我计划从1.5到2.2升级。
- 是否有任何问题已发生android 2.2？
- 如果我想要降低较低版本，怎么可能？ （即回滚到旧版本）
Currently I am using HTC Hero with Android 1.5 and as we know right now Android 2.2 (Froyo) has been released, so i am planning to upgrade from 1.5 to 2.2.
Regarding updating, I have the following questions:
Unfortunately, if you were running SDK 1.6 or later you could just update without installing a new SDK. But for 1.5 you need to install a new SDK. Per this link from Google http://developer.android.com/sdk/installing.html (see quoted text below)...
How ever, you can backup your projects and move them into the new SDK environment. So it looks like all may not be lost. Just read that link above pretty thoroughly.
If you are currently using the Android 1.6 SDK or later and want to update to the latest tools or platforms, you do not need to install a new SDK. Instead, you can simply update the individual components in your SDK using the Android SDK and AVD Manager tool. For information about how to do that, see Updating SDK Components
If you are using Android 1.5 SDK or earlier, you should install a new SDK as described in this document and move your application projects to the new SDK environment.