Lines often have a set of controls, such as gain and pan, that affect the audio signal passing through the line.

  Lines often have a set of controls, such as gain and pan, that affect the audio signal passing through the line. Java Sound's Line objects let you obtain a particular control object by passing its class as the argument to a getControl method.

Because the various types of controls have different purposes and features, all of their functionality is accessed from the subclasses that define each kind of control.