TUTORIAL 38
Sensing a Disturbance
Continuing our additions to LunchList, we really need a solution to the age-
old problem of deciding where to go for lunch. For that, a good old-
fashioned random selection would be a fine starting point. But, to make it
more entertaining, we should trigger the selection by shaking the device.
Shake the phone when on the list of restaurants, and a randomly-selected
restaurant will be shown via its DetailForm.
Step-By-Step Instructions
First, you need to have completed the previous tutorial. If you are
beginning the tutorials here, or if you wish to not use your existing work,
you can download a ZIP file with all of the tutorial results, and you can copy
the 37-Camera edition of LunchList to use as a starting point.
Step #1: Implement a Shaker
We need something that hooks into the SensorManager and watches for
shaking events, where a "shake" is defined as a certain percentage over
Earth's gravity, as determined by calculating the total force via the square
root of the sum of the squares of all three dimensional forces.
And if that was total gibberish to you, this is why humankind has developed
encapsulation and copy-and-paste.