Are you seeing this on eclipse when you plug your Android device to your Ubuntu box?

Serial Number: ??????????
AVD Name: N/A
Target: unknown
State: ??

Here’s the solution:

1. Create a script to fix this next time it happens, let’s call it “android_device_reset” and save it on a folder contained on your $PATH environment variable.

#!/bin/bash
# android_device_reset script
sudo adb kill-server
sudo service udev stop
sudo adb start-server
sudo adb devices

Save it and make it executable

chmod +x android_device_reset

2. Open this file /etc/udev/rules.d/51-android.rules

Make sure it looks something like this

SUBSYSTEMS=="usb", SYSFS{idVendor}=="0bb4", MODE=="0666"
SUBSYSTEMS=="usb", SYSFS{idVendor}=="22b8", MODE=="0666"

Each line represents a different android device. If you have just one, the file should be one line long.

On that example I’ve configured the rules for a Motorola Droid and a Nexus One.
If you need to know the idVendor numbers for your Android device go here
developer.android.com/guide/developing/device.html#VendorIds

3. Whenever the problem happens, just open a terminal and type

android_device_reset

It’ll ask you for your password, only administrative users will be able to execute the script.

Hope this helps.

This is a report done on all the projects that make up for the android project, my copy of it is synced as of May 23rd 2010, 6pm
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Nexus 1 indeed.

17 files get their MD5 calculated on the Droid

and 17 files get their MD5 hash calculated on the Nexus 1

Nexus 1 pwns.

Here’s the code in case you’re curious.

	public void onClick(View v) {
                                _logTextView.setText("MD5 Benchmark on " + Build.DEVICE + "\n\n");
				if (GlobalVariables.APP_CONTEXT == null)
					GlobalVariables.APP_CONTEXT = getApplicationContext();

				List<FileDescriptor> sharedAudioFiles = Engine.INSTANCE.LIBRARIAN.getSharedAudioFiles(0, 17);
				for (FileDescriptor fs: sharedAudioFiles) {
					long start = 0;
					String md5 = null;
					long length = 0;
					try {
						start = System.currentTimeMillis();
						File f = new File(fs.path);
						length = f.length();
						md5 = FrostWireUtils.getMD5(f);

					} catch (Exception e) { }
					long time = System.currentTimeMillis() - start;
					_logTextView.append(FrostWireUtils.getBytesInHuman(length) + " in " + time + " ms @ " + (length/(double) time)*1000 + " b/s\n");
				}
			}

And here’s how we do the MD5

	public final static String getMD5(File f) throws Exception {
		MessageDigest m = MessageDigest.getInstance("MD5");

		byte[] buf = new byte[65536];
		int num_read;

		InputStream in = new BufferedInputStream(new FileInputStream(f));

		while ((num_read = in.read(buf)) != -1) {
			m.update(buf, 0, num_read);
		}

		String result = new BigInteger(1, m.digest()).toString(16);

		// pad with zeros if until it's 32 chars long.
		if (result.length() < 32) {
			StringBuffer padding = new StringBuffer();
			int paddingSize = 32 - result.length();
			for (int i = 0; i < paddingSize; i++)
				padding.append("0");

			result = padding.toString() + result;
		}

		return result;
	}

Recently I became curious on how many lines of code a huge open source project I contribute to has on what languages. I found a tool called “cloc” on sourceforge, check out the results and I dare you to think again if you think you’re in a big project.
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I was going to make a tutorial, but then I figured that making a video would be a much better way to show this.
As for the code that you could grab from a tutorial, there’s a link at the end of the post with all the code shown in the video demo.

The video demo covers how to create and run Unit Test classes for regular Java classes on Android, and also how to create and run Unit Test classes that test classes that depend on Android “Context” or “Activity” objects.

If your Android unit tests are not running because of frustrating error messages, the time spent watching this video will save you a lot of reading and headaches.

Check the screencast after the break

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1. C# 73,833
2. Java 43,006
3. PHP 35,371
4. Javascript 31,244
5. C++ 27,340
6. Python 22,070
7. Objective-C 10,350
8. Ruby 8,773
9. VB.net 7,778
10. ActionScript (Flash) 5,230
11. Perl 4,496

What do these numbers mean to you? Languages on the rise of popularity among programmers, or lack of good documentation?

[buzz href="http://www.google.com/buzz/gubatron2/UJr3LGeN53k/Programming-Languages-Popularity-by-the-number-of" liked="14"]

Sometimes you need to create graphics, or compose images and have them saved as regular PNGs, JPEGs or GIFs.

Here’s a quick and dirty reference of how to do it with BufferedImages, Graphics2D and javax.imageio.*.
Very straightforward.

import java.awt.Color;
import java.awt.Graphics2D;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;

import javax.imageio.ImageIO;
...

//1. Create a BufferedImage, in this case a simple 1024x768 using only RGB colors (you could use alpha for example)
BufferedImage bufferedImage = new BufferedImage(1024, 768, BufferedImage.TYPE_INT_RGB);

//2. Get a hold of a Graphics2D object to do all the painting and compositing on the BufferedImage
Graphics2D graphics = bufferedImage.createGraphics();

//3. Do the painting... in this case, I just filled with yellow
graphics.setColor(new Color(255,255,0));
graphics.fillRect(0, 0, bufferedImage.getWidth(), bufferedImage.getHeight());

//4. Write the image
try {
    ImageIO.write(bufferedImage, "png",new File("test.png"));
} catch (IOException e) {
   e.printStackTrace();
}

You may be running several independent but similar servers at the same time and wasting time by executing commands in all of them one by one.

Wouldn’t it be nice to send a command to all of them at once? or to monitor all of them at once.

The following script can be used as a building block to more complex automation tasks for a small size set of servers. (If you’re managing over 50 servers, I’d probably consider looking a different way to arrange servers (map/reduce cluster), but if you’re doing something below that number this might suffice)

#!/usr/bin/python                                                                                                                                                                                                                                                      

#########################################################
# Author: Angel Leon (gubatron@gmail.com) - October 2009
#
# Invokes a command locally and invokes the same command
# in all machines under the specified username, servers
#
# Requirement: Have a public ssh_key for that user on all
# the other machines so you don't have to authenticate
# on all the other machines.
#########################################################
import sys
import os

# set the username that has access to all the machines here
user='safeuser'

# add all your server names here
servers=['server1.mydomain.com','server2.mydomain.com','server3.mydomain.com']

if __name__ == "__main__":
  if len(sys.argv) < 2:
    print "Usage: ssh_map_command <cmd>"
    sys.exit(0)

  cmd= ' '.join(sys.argv[1:])

  #Execute locally first
  print cmd
  os.system(cmd)

  #Execute for all the servers in the list
  for server in servers:
    remote_cmd="ssh %s@%s %s" % (user,server,cmd)
    print remote_cmd
    os.system(remote_cmd)
    print

Save as ssh_map_command and chmod +x it.

Sample uses
Check the average load of all machines at once (then use output to mitigate high load issues)

$ ssh_map_command uptime

Send HUP signal to all your web servers (put it in an alias or other script… and that’s how you start building more complex scripts)

$ ssh_map_command ps aux | grep [l]ighttpd | kill -HUP `awk {'print $2'}`

Check if processes are alive, check memory usage on processes across different machines, grep remote all logs at once, svn up on all machines, rsync from one to many, hey, you can even tail -f and grep all the logs at once, you can go nuts with this thing. Depends on what you need to do.

Requirements

• For convenience you should probably set up ssh public/private keys between the main machine and the other machines (or they can all trust each other and you can execute on any) so that you can execute commands on all the machines without having to enter passwords.
• Put the script on your $PATH.
• python

Security Advisory
Make sure only the desired user has read/write/execute access to it and keep your private ssh keys safe (preferably only read and execute for the owner, and no permissions whatsoever to anybody else chmod 500 ssh_mod_map), if possible change them as often as possible, for it may become a big security whole if an attacker can manage to write code on this script, specially if you have cronjobs invoking it. Your attacker would only need to change code here to mess up all of your machines.

Disclaimer and Call for Knowledge
Please, if someone knows of a standard way to map commands to multiple servers, please let me know in the comment section, in my case I needed a solution and I wrote a quick and dirty python script and tried to secure it as best as I could, by no means I’m saying that this is the best solution to mapping commands, in fact I believe it might be the least efficient way, however it works good enough for my personal needs.

Just Type…
sudo dpkg-reconfigure tzdata

…and follow the instructions on screen.

The process should look something like the following:

Select your Region

Select a city on your time zone

You’re done.

Tip
You can always check the status of your configuration using
sudo debconf-show tzdata

You could for example map that command via ssh to several machines and grep for “*”, that way you could easily spot servers with wrong timezones very quickly.

Type the following on your cmd line (or make into an alias)

cat ~/.bash_history | sort | uniq -c | sort -r | head

In my case they are (for this week)

ls
fg
svnSync (script I created)
stats_fetch; stats_display (other scripts)
cd
crontab -e
ps aux | grep
ssh_map_command (another script)
python
emacs -nw