Eclipse + Android SDK bugs and workarounds, common mistakes

If you have already used Eclipse with Android SDK, you probably have some experience with known and unknown bugs. I'd like to show you some of these, and help you how to solve them.
First of all, if you got the following message from the running Emulator, except that the process is your Project, then you have to open up DDMS.
You can find DDMS button in the upper-right corner of Eclipse. Once you are in DDMS, Select your running Emulator from the left, and see what is happening by Clicking on LogCat tab (bottom of the screen).
Scroll all the way down, then start scrolling upwards, until red-colored lines show up. Probably you have NullPointer Exception or something like that, so I can't help you on that one, but I try my best to solve some other problems that you may have had.

1.Android Version 1.6 (Level 4) DDMS bug:

„emulator-5554 disconnected! Cancelling „

When you are running an emulator with the version mentioned, and you go to DDMS Tab ? File Explorer, then after a few seconds your emulator is going to be disconnected. Reason unknown, but there's a workaround although not the best..

Solution:
If you want to use File Explorer: Right Click on your Project, Properties - Android, and select the version 2.1 (Level 7).
Save your Project. After you've tested everything you want in File Explorer, change your version settings back.
If you don't need File Explorer: Simply close the File Explorer Tab in DDMS.

2.emulator: ERROR: the user data image is used by another emulator. aborting:

[2010-03-18 09:00:40 - PhoneLister]Android Launch!
[2010-03-18 09:00:40 - PhoneLister]adb is running normally.
[2010-03-18 09:00:40 - PhoneLister]Performing com.xy activity launch
[2010-03-18 09:00:40 - PhoneLister]Automatic Target Mode: Preferred AVD 'android16emu' is not available. Launching new emulator.
[2010-03-18 09:00:40 - PhoneLister]Launching a new emulator with Virtual Device 'android16emu'
[2010-03-18 09:01:06 - Emulator]emulator: ERROR: the user data image is used by another emulator. aborting

Solution:
That means you have to close your already running Emulator, then Eclipse is going to start a new one if you click on Run/Run Debugger again.
The reason can be many various things, for instance the bug we've discussed above.

3.Toast doesn't print/show text:

It's actually not a bug. Sometimes you can easily forget to add the „.show()” method by mistake.
So instead of: Toast.makeText(this, "blabla", 3);
use: Toast.makeText(this, "blabla", 3).show;

4.Changes in codeline don't have any effect when an Emulator is running:

This is a minor problem. Sometimes your emulator data-image file is not updating itself, so no matter what's in the codeline, actually you are running a previous version of your Application. (Even after several „re-Run”)

Solution:
Restarting emulator with the option „Wipe User Data” solves the problem.

At last, but not least, you may have to restart your Eclipse workspace once in a while, to get things working again. I hope you found this article helpful, and feel free to add comments and share bugs/solutions that you know.