title: Android: How do I force the update of all widgets of a particular kind
body: <p>I have seen many questions along these lines, and I keep seeing the same answer over and over. I don't want to have to have a Service for every kind of widget my app has, especially seeing as my app already has 2 persistent services.</p>
  
  <p>Specifically, if one of my existing services sees that data has changed, I want to update my widgets. Doing this on a timer is annoying, as it could be days between updates or there might be several within one hour. I want my widgets to ALWAYS show up to date information.</p>
  
  <p>Android widget design seems to work on the basis that your widget pulls information when it wants it, I think there are many sensible scenarios where an activity may wish to push data to a widget.</p>
  
  <p>Read the answer below for how I worked out how to do precisely this. As far as I can see there are no adverse effects if it is done properly.</p>