The challenge is that you need to coordinate multiple methods in multiple classes across multiple threads.
挑战在于，您需要跨多个线程协调多个类中的多个方法。
2
Finally, a variety of utility classes for styling, data formats, coordinate storage, and more are available.
最后，是用于样式化、数据格式化、坐标存储等的各种实用工具类。
3
The J2EE activity Service specification defines a set of interfaces and classes that coordinate and control the execution of actions within an activity.