emulator shortcut

Alt+Enter	Maximizes the emulator.
Ctrl+F11	Changes the orientation of the emulator from landscape to portrait and vice versa.
F8	Turns the network on and off.

During the creation of an emulator you can choose if you either want Snapshot or Use Host GPU enabled.
The dialog implies that you can select both options, but if you do, you get an error message that these options can not be selected together.
If you select the Snapshot option, the second time you start the device it is started very fast, because the AVD stores its state if you close it. If you select Use Host GPU the AVD uses the graphics card of your host computer directly which makes the rendering on the emulated device much faster.

http://www.vogella.com/tutorials/Android/article.html

用intel映像更快，因为不需要机器指令的转换。创建avd时，google device会有google service可用，而android device没有。

At the time of this writing your also need to download and install extra drivers for MS windows.
After the download you find the driver in your Android installation directory in the extras folder. You need to install the drivers by running starting the .exe file.

Android also provides resources. These are called system resources. System resources are distinguished from local resources by the android namespace prefix. For example, android.R.string.cancel defines the platform string for a cancel operation.

In reality this option is rarely used, as an application installed on the external storage is stopped once the device is connected to a computer and mounted as USB storage.

Calculating the layout and drawing the views is a resource intensive operation. You should use the simplest layout possible to achieve good performance. For example, you should avoid nesting layout managers too deeply or avoid using complex layout managers in case a simple layout manager is sufficient.
RelativeLayout is a complex layout manager and should only be used if such a complex layout is required, as it performs a resource intensive calculation to layout its children.
As of Android 4.0 the most relevant layout managers are LinearLayout, FrameLayout, RelativeLayout and GridLayout.
AbsoluteLayout is deprecated and TableLayout can be implemented more effectively via GridLayout.

Some API is still marked as provisional. This means that the API might be changed in the future. If you use such API, you must be prepared that you might have to make some adjustments to your application in a future Eclipse release.