How to Determine if Android Device has a Magnetometer (Compass)

public static final String FEATURE_SENSOR_COMPASS was added in API level 8
Feature for getSystemAvailableFeatures() and hasSystemFeature(String).
The device includes a magnetometer (compass).
Constant Value: "android.hardware.sensor.compass"

1. Get a PackageManager Instance named myPackageManager.

2. Create a Boolean Variable named bolCompassSupported. 

3. Set the Minimum and Target SDK version  to 8 or greater. 

4. In the onCreate method, add the below code. This will return the compass feature availability to a boolean named bolCompassSupported. It will then display a toast displaying the compass feature availability of the device to the user.

bolCompassSupported = myPackageManager.hasSystemFeature(PackageManager.FEATURE_SENSOR_COMPASS);

if (bolCompassSupported) {

Toast.makeText(this, "Device has a Compass", Toast.LENGTH_LONG).show();

} else {

Toast.makeText(this, "Device does NOT have a Compass!", Toast.LENGTH_LONG).show();

}

5. Compile and run!

Resources:
http://developer.android.com/reference/android/content/pm/PackageManager.html#FEATURE_SENSOR_COMPASS