Any way to have initial delay for PeriodicWorkRequ

问题:

For OneTimeWorkRequest, we can have setInitialDelay to specific the initial delay.

However, there isn't such facility for PeriodicWorkRequest.

Is there any reliable way to achieve so?

One of the less reliable way, is to have a delayed OneTimeWorkRequest worker, to setup PeriodicWorkRequest. However, that's quite cumbersome, and create a possibility, where OneTimeWorkRequest may fail and not able to install PeriodicWorkRequest.

回答1:

Since the system runs your work you can't control the exact time it will run..

Your best option for creating a work execution delay is to use this PeriodicWorkRequest.Builder and supply a flexInterval as the 4th parameter:

PeriodicWorkRequest build = new PeriodicWorkRequest.Builder(
     SyncJobWorker.class, 
     REPEAT_INTERVAL, // repeatInterval
     TimeUnit.MILLISECONDS, // repeatIntervalTimeUnit
     FLEX_INTERVAL, // flexInterval
     TimeUnit.MILLISECONDS) // flexIntervalTimeUnit
       .build();

Docs ref: https://developer.android.com/reference/androidx/work/PeriodicWorkRequest.Builder#periodicworkrequestbuilder_2

Creates a PeriodicWorkRequest to run periodically once within the flex period of every interval period. See diagram below. The flex period begins at intervalMillis - flexMillis to the end of the interval. intervalMillis must be greater than or equal to PeriodicWorkRequest.MIN_PERIODIC_INTERVAL_MILLIS and flexMillis must be greater than or equal to PeriodicWorkRequest.MIN_PERIODIC_FLEX_MILLIS.