The Flex class hierarchy All visual components are derived from the UIComponent ActionScript class. Flex nonvisual components are also implemented as a class hierarchy in ActionScript. The most commonly used nonvisual classes are the Validator, Formatter, and Effect base classes.
在Using Flex4說明文件中提到
The compilers use the Java JRE. As a result, you can also configure settings such as memory allocation and source path with the JVM arguments.