An emulator platform simulates the execution of an application on one or more target devices. For example, the Sun Java Toolkit for CDC enables you to run applications on several example devices, or "skins" included with the emulator. An emulator allows you to understand the user experience for an application on a particular device, and to test the portability of the application across different devices.
In the IDE, you specify the emulator platform in the project properties. Many emulator platforms are packaged as software developer kits (SDKs) from manufacturers of mobile devices.
Some of the differences between emulators include their support for:
Note that having an emulator does eliminate the need for testing your application on the actual target devices. An emulator can only approximate a device's user interface, functionality, and performance. For example, an emulator may not accurately simulate processing speed, so an application may run faster, or slower, on a target device than it does on an emulator.