Callback Interfaces, Delegates, and Events
Up to this point in the text, every application you have developed added various bits of code to Main(), which, in some way or another, sent requests to a given object. However, you have not yet examined how an object can talk back to the entity that created it. In most programs, it is quite common for objects in a system to engage in a two-way conversation through the use of callback interfaces, events, and other programming constructs. To set the stage, this chapter begins by examining how interface types may be used to enable callback functionality.
KeywordsSugar Covariance Prefix J2EE
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