Finding and identifying sensors

To start using the Mobile Sensor API, you need to find the available sensors to be used. This is done with the SensorManager.findSensors() method. You can find the sensor by specifying quantity or context, or by entering a definite sensor URL describing desired sensor properties. These are described in the following example:

// Find all sensors
SensorInfo[] sensorInfos = SensorManager.findSensors( null, null );

// Find all “acceleration” sensors, the contextType is left undefined
SensorInfo[] sensorInfos = SensorManager.findSensors( "acceleration",  null );

// Or with URL
SensorInfo[] sensorInfos = SensorManager.findSensors( "sensor:acceleration" );

Depending on the search parameters, findSensors() can return several matching SensorInfo objects. To find the correct sensor, you may need to refine your search further by some of the following criteria:

**Table:** Common ChannelInfo search criteria
Criterion	Description	Values
`Data type`	The data type of the channel. This is one of the most useful criteria as it is very common for channels to use different data types.	`TYPE_INT` `TYPE_DOUBLE` `TYPE_OBJECT`
`Unit`	The unit in which data values are presented. These are usually derived from the `Unit` class.	See table SI units in `Unit` class description.
`Measurement range`	All measurement ranges for this channel. Measurement ranges are the resolution and the possible largest and smallest values of the sensor.	For more information see class`MeasurementRange`

**Table:** Common SensorInfo search criteria
Criterion	Description	Values
`Context`	The context type of the sensor. Context divides sensor types into four categories depending on the environment where they are used.	`USER` `DEVICE` `AMBIENT` `VEHICLE`
`Model`	The model of the sensor specified by vendor specific.	Returns the sensor model as a String
`URL`	The URL of the sensor. It starts with the `sensor:` prefix and contains at least the quantity, model, and context type of the sensor.	Returns the URL as a String

For a full list of searchable criteria, see ChannelInfo and SensorInfo.

Example: identifying data types

The following code example determines the amount of available channels in the sensor and handles them according to data type. The example uses the DataListener interface to retrieve the sensor data. See section Using data listeners for more information.

public void dataReceived(SensorConnection sensor, Data[] data, boolean isDataLost ) {
    ChannelInfo[] channelinfo = sensor.getSensorInfo().getChannelInfos();
    for(int i = 0; i < channelinfo.length; i++) {
        switch (channelinfo[i].getDataType()) {
            case ChannelInfo.TYPE_INT:
                displayData(data[i].getIntValues());
                break;
            case ChannelInfo.TYPE_DOUBLE:
                displayData(data[i].getDoubleValues());
                break;
            case ChannelInfo.TYPE_OBJECT:
                displayData(data[i].getObjectValues());
                break;
        }
    }
}