scheduleatfixedrateschedule和scheduleAtFixedRate的区别

schedule和scheduleAtFixedRate的区别

scheduleAtFixedRate() 与 schedule() 的区别 scheduleAtFixedRate() 与 schedule()看起来功能很像，其实不然。

scheduleAtFixedRate()的API说明有这样一段话： If an execution is delayed for any reason (such as garbage collection or other background activity), two or more executions will ur in rapid ession to "catch up." In the long run, the frequency of execution will be exactly the reciprocal of the specified period. 翻译过来的大概意思是：如果任务比较复杂，或者由于任何原因（如垃圾回收或其他后台活动）而延迟了某次执行，则scheduleAtFixedRate方法将快速连续地出现两次或更多的执行，从而使后续执行能够“追赶上来”。

从长远看，执行的频率很接近指定的周期。

而schedule()的API说明是这样写的： In fixed-delay execution, each execution is scheduled relative to the actual execution time of the previous execution. If an execution is delayed for any reason (such as garbage collection or other background activity), subsequent executions will be delayed as well.In the long run, the frequency of execution will generally be slightly lower than the reciprocal of the specified period. 翻译过来大概意思是：如果任务比较复杂，或者由于任何原因（如垃圾回收或其他后台活动）而延迟了某次执行，则接下来的任务也会被延迟，从长远看，schedule执行的频率将稍微比指定的周期要低点。