Blackberry log file - blackberry

Question

Is there a method for creating a log file using a blackberry api ?
Something like log4j ?
I'd like to save this log file on pc running the emulator, is this possible ?

Answer 1

At Antair, during development of our BlackBerry applications, we often include a debug console in the dev builds of our apps.
With the debug console, all debug output hits the output screen when the dev build is running in the simulator, and when the dev build runs on a physical test device, the debug output is automatically persisted and is available to view on a dedicated screen that can be pulled up via a menu option or button. With a little code modification, you can easily have the debug log be rerouted to a file, emailed or sent over a network connection.
The code below is a stripped-down version of the debug console we use at our company.
Using the console is easy. Include the code in your project, fill out the PERSISTENCE_GUID for your application, set the TAGID string to identify your application name in the debug logs, and when you want to output a debug statement, simply call Debug.print(”Something happened here…“);
Each line of the debug output, both in the output window when running in a simulator, and in the debug console screen when viewed on a device, will contain your debug message, the thread number on which the call was made (useful for thread/ui debugging), and the date/time of the log statement, with a millisecond timestamp for performance profiling.
To view the debug console on a real device, simple put in a call to pushScreen(new AntairLogScreen()). The screen has a built-in menu item to clear the persisted log messages, and will dismiss itself like a regular application screen.
If you’re running the RIM compiler preprocessor to switch between development, QA, and production builds, you can simply put in a call to set Debug.ENABLED = false for everything but the development builds, and the debug console will be there when you need to debug and go away quietly when you don’t need it.
The code is below.
// ---------------------------------------------------------------------------
// Antair Debug Log (for the BlackBerry API)
// http://www.antair.com
// ---------------------------------------------------------------------------
package com.antair.examples.debug;
import net.rim.device.api.i18n.SimpleDateFormat;
import java.util.Date;
import net.rim.device.api.collection.util.BigVector;
import net.rim.device.api.system.PersistentObject;
import net.rim.device.api.system.PersistentStore;
import net.rim.device.api.ui.MenuItem;
import net.rim.device.api.ui.component.Menu;
import net.rim.device.api.ui.component.RichTextField;
import net.rim.device.api.ui.container.MainScreen;
import net.rim.device.api.util.Persistable;
final class Debug implements Persistable
{
final static boolean ENABLED = true;
final static String TAGID = "MY_PROJECT";
final static long PERSISTENCE_GUID = /* YOUR OWN PERSISTENCE GUID */;
private BigVector _messages = new BigVector();
static String print(String str)
{
if ( Debug.ENABLED )
{
StringBuffer sb = new StringBuffer();
sb.append(TAGID);
sb.append("\n");
sb.append(Thread.currentThread().toString());
sb.append("\n");
sb.append(new SimpleDateFormat("MM/dd/yy HH:mm:ss:SSS").format(
new Date()));
sb.append("\n");
sb.append(str); sb.append("\n");
str = sb.toString();
System.out.println(str);
System.out.flush();
Debug d = load();
d._messages.addElement(str);
save(d);
}
return str;
}
static BigVector getPersistedMessages()
{
return load()._messages;
}
static void clearPersistedMessages()
{
save(new Debug());
}
private static Debug load()
{
Debug d = null;
try
{
PersistentObject po =
PersistentStore.getPersistentObject(Debug.PERSISTENCE_GUID);
synchronized(po)
{
Object obj = po.getContents();
d = (obj == null) ? new Debug() : (Debug)obj;
}
}
catch ( Exception e )
{
d = new Debug();
}
return d;
}
private static void save(Debug d)
{
try
{
PersistentObject po =
PersistentStore.getPersistentObject(Debug.PERSISTENCE_GUID);
synchronized(po)
{
po.setContents(d);
po.commit();
}
}
catch ( Exception e )
{
}
}
}
final class ClearAntairLogScreenMenuItem extends MenuItem
{
ClearAntairLogScreenMenuItem(int position)
{
super("Clear Log", position, 0);
}
public void run()
{
Debug.clearPersistedMessages();
}
}
final class AntairLogScreen extends MainScreen
{
AntairLogScreen()
{
super(MainScreen.DEFAULT_CLOSE|MainScreen.DEFAULT_MENU);
StringBuffer text = new StringBuffer();
BigVector logItems = Debug.getPersistedMessages();
for ( int i = 0 ; i < logItems.size() ; ++i )
{
text.append((String)logItems.elementAt(i) + "\n");
}
add(new RichTextField(text.toString()));
}
protected void makeMenu ( Menu menu, int instance )
{
menu.add(new ClearAntairLogScreenMenuItem(100000));
}
}

Answer 2

BlackBerry has its own log facility - EventLogger, but I find it to be ugly. You can write to EventLogger, but you can not view it as easily as you might with other logs or for example you can not extract the content programmatically to send over http/email.
I think it is much more comfortable to use your custom logger class that writes log entries directly to a log file on the SD card. Since the SD card on the emulator is a folder on your PC, you can easily monitor the app with any PC log viewer in real time.
Also as a bonus with such approach you can have some code to send the log over http/email. Such logging on a real device will slow down the app significantly, so it should not be normally used in production, but your app could have such option (to enable the debug mose) so it'll allow to know the reason which otherwise would remain unknown.