JSR 256 battery events

Question

How can I detect whenever the power cord is unplugged from electrical socket using JSR 256?

Answer 1

You would add javax.microedition.io.Connector.sensor to the API Permissions tab of the Application Descriptor of the project properties.

Answer 2

From a quick look at the specifications of the JSR:

(you might want to look for code examples, starting with Appendix D of the spec itself, the latest JavaME SDK, Sony Ericsson developer website, then google)

As always, I would be worried about fragmentation in the diverse implementations of the JSR, but here's my first idea:

import javax.microedition.sensor.*;

SensorInfo[] powerSensorInfoArray = SensorManager.findSensors("power","ambient");

//let's assume there is one SensorInfo in the array.

//open a connection to the sensor.

SensorConnection connection = (SensorConnection)Connector.open(powerSensorInfoArray[0].getUrl(), Connector.READ);

// add a DataListener to the connection

connection.setDataListener(new MyDataListener(), 1);

// implement the data listener

public class MyDataListener implements DataListener {

public void dataReceived(SensorConnection aSensor, Data[] aDataArray, boolean isDataLost) {

//let's assume there is only one channel for the sensor and no data was lost.

// figure out what kind of data the channel provides.

int dataType = aDataArray[0].getChannelInfo().getDataType();

//now, I suggest you switch on dataType and print the value on the screen

// experimentation on the JSR256 implementation you're targetting seems to be

// the only way to figure out out power data is formatted and what values mean.

//only one of the following 3 lines will work:

double[] valueArray = aDataArray[0].getDoubleValues();
int[] valueArray = aDataArray[0].getIntValues();
Object[] valueArray = aDataArray[0].getObjectValues();

// let's assume one value in the valueArray

String valueToPrint = "" + valueArray[0];

// see what happens with that and you plug or unplug the power supply cable.

}

}

You'll need to add javax.microedition.io.Connector.sensor to your MIDlet permissions.

-------EDIT------

Documentation from the JSR-256 implementation on Sony-Ericsson Satio phone (S60 5th edition):

The battery charge sensor has the following characteristics:

• Quantity: battery_charge

• Context type: device

• URL: sensor:battery_charge;contextType=device;model=SonyEricsson

• Channels: (index: name, range, unit)

• 0: battery_charge, 0-100, percent

• 1: charger_state, 0-1, boolean