Finding Your Way - Beginning Java ME Platform - page 487

The Criteria object you create specifies any specific requirements you have regard-
ing the locations your application will request. The Location API implementation uses
these to configure and select a specific LocationProvider instance. Table 17-1 shows the
specific criteria you can specify within a Criteria object. If the implementation cannot
explicitly meet your criteria, it will make its own best-effort selection, provided that the
resulting LocationProvider instance meets your specific cost criteria. The Criteria class
provides the constants NO_REQUIREMENT , POWER_USAGE_LOW , POWER_USAGE_MEDIUM , and
POWER_USAGE_HIGH to describe the case where no criteria apply and to describe specific
power-consumption criteria. Listing 17-1 sets a single criterion for the LocationProvider
instance: that the location determination fall within ten meters of the probable location
of the device.

Table 17-1. Criteria for Location Provider Configuration

Criteria Units Default Value Setter Accessor

NO_REQUIREMENT setHorizontalAccuracy getHorizontalAccuracy Horizontal Meters

accuracy

NO_REQUIREMENT setVerticalAccuracy getVerticalAccuracy Vertical Meters

accuracy

Milliseconds NO_REQUIREMENT setPreferredResponseTime getPreferredResponseTime Preferred

response
time

int NO_REQUIREMENT setPreferredPowerConsumption getPreferredPowerConsumption

Power

consumption

boolean true (permitted setCostAllowed isAllowedToCost

Cost

allowed to incur cost

to the user)

boolean false setSpeedAndCourseRequired isSpeedAndCourseRequired Speed

and course
required

boolean false setAltitudeRequired getAltitudeRequired Altitude

required

boolean false setAddressInfoRequired isAddressInfoRequired Address

required

The LocationProvider class is a factory of LocationProvider instances, as well as a
factory of Location objects and a notifier of location and proximity information. You
obtain a specific LocationProvider instance through the class's LocationProvider.
getInstance method, passing a Criteria instance that describes the restrictions that
should apply to the positioning work the LocationProvider will perform. Once you have