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Checking battery level in Java ME

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|sourcecode= [[Media:Checking battery level in J2ME.zip]]  
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|id=CS001201
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|platform=S60 3rd Edition, S60 3rd Edition, FP1, S60 3rd Edition, FP2
+
|devices=Nokia E70, Nokia N78
+
|category=Java ME
+
|subcategory=System information
+
|creationdate=December 9, 2008
+
|keywords=java.lang.System.getProperty, com.nokia.mid.batterylevel
+
 
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|sdk=<!-- SDK(s) built and tested against (e.g. [http://linktosdkdownload/ Nokia Qt SDK 1.1]) -->
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This code snippet demonstrates how to retrieve the current battery level.
 
This code snippet demonstrates how to retrieve the current battery level.
  
The application retrieves the system property <tt>com.nokia.mid.batterylevel</tt>
+
The application retrieves the system property {{Icode|com.nokia.mid.batterylevel}}
 
which contains the current battery level (in per cent) and displays it.
 
which contains the current battery level (in per cent) and displays it.
  
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==Supplementary material==
 
==Supplementary material==
  
The source file and executable application are available for download at [[Media:Checking_battery_level_in_J2ME.zip]].
+
The source file and executable application are available for download at [[Media:Checking battery level in J2ME.zip]].
  
 
[[Category:Java ME]][[Category:Code Examples]][[Category:Code Snippet]]
 
[[Category:Java ME]][[Category:Code Examples]][[Category:Code Snippet]]

Revision as of 07:36, 10 May 2012

Article Metadata
Code ExampleTested with
Devices(s): Nokia E70, Nokia N78
Compatibility
Platform(s): S60 3rd Edition, S60 3rd Edition, FP1, S60 3rd Edition, FP2
Series 40
Series 40 DP 2.0
Series 40 DP 1.1
Symbian
Nokia Belle
Java Runtime 2.3 for Symbian
Article
Keywords: java.lang.System.getProperty, com.nokia.mid.batterylevel
Created: vltsoy (27 Nov 2008)
Last edited: hamishwillee (10 May 2012)


Contents

Overview

This code snippet demonstrates how to retrieve the current battery level.

The application retrieves the system property com.nokia.mid.batterylevel which contains the current battery level (in per cent) and displays it.

Note that in Series 40 platform only signed MIDlets under operator domain can retrieve this information.

Source file: BatteryLevel.java

import javax.microedition.lcdui.Command;
import javax.microedition.lcdui.CommandListener;
import javax.microedition.lcdui.Display;
import javax.microedition.lcdui.Displayable;
import javax.microedition.lcdui.Form;
import javax.microedition.lcdui.StringItem;
import javax.microedition.midlet.MIDlet;
 
 
public class BatteryLevel extends MIDlet implements CommandListener{
 
private Display display;
private Form form;
private Command exitCommand;
private Command refreshCommand;
private StringItem level;
 
 
/**
* Constructor. Constructs the object and initializes displayables.
*/

public BatteryLevel() {
form = new Form("Battery level.");
 
exitCommand = new Command("Exit", Command.EXIT, 2);
refreshCommand = new Command("Refresh", Command.OK, 1);
 
level = new StringItem("", "");
form.append(level);
 
form.addCommand(exitCommand);
form.addCommand(refreshCommand);
form.setCommandListener(this);
 
display = Display.getDisplay(this);
display.setCurrent(form);
 
checkBatteryLevel();
}
 
/**
* From MIDlet.
* Called when the MIDlet is started.
*/

public void startApp() {
// No implementation required.
}
 
/**
* From MIDlet.
* Called to signal the MIDlet to enter the Paused state.
*/

public void pauseApp() {
// No implementation required.
}
 
/**
* From MIDlet.
* Called to signal the MIDlet to terminate.
* @param unconditional whether the MIDlet has to be unconditionally
* terminated
*/

public void destroyApp(boolean unconditional) {
// No implementation required
}
 
/**
* From CommandListener.
* Called by the system to indicate that a command has been invoked on a
* particular displayable.
* @param cmd the command that was invoked
* @param displayable the displayable where the command was invoked
*/

public void commandAction(Command c, Displayable d) {
if (c == refreshCommand) {
checkBatteryLevel();
} else if (c == exitCommand) {
notifyDestroyed();
}
}
 
/**
* Called to read current battery level.
*/

private void checkBatteryLevel() {
String property = System.getProperty("com.nokia.mid.batterylevel");
if (property == null) {
level.setLabel("Error:\n");
level.setText("Unable to retrieve current battery level.\n" +
"It's only available for signed midlets " +
"under operator domain.");
} else {
level.setLabel("Current battery level:");
level.setText("\n"+property+"%");
}
}
}

Postconditions

This code displays the current battery level in per cent.

Supplementary material

The source file and executable application are available for download at Media:Checking battery level in J2ME.zip.

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