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Debugging database

Fri, 03/12/2010 - 02:25 | by gabor

When I first tried to manage an sqlite database on an adroid device I was not sure about where I fail in it. Can I even insert the records into the database, or I fail only to read the data from it? So I started to search for possibilities to debug the database lifecycle.

The system stores databases in the /data/data/package_name/databases folder by default.

In a command line using the adb (Android Debug Bridge - found in the android sdk tools library) you can access the databases on a running emulator like below:

  1. adb -s emulator-5554 shell
  2.  
  3. sqlite3 /data/data/package_name/databases/database_name

After this you can type normal SQL commands to test the content. For example:

  1. SELECT * FROM table_name;

This will list the table content (in an ugly format), or say that it does not exists.

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Days to Xmas widget tutorial

Mon, 03/08/2010 - 03:17 | by jozsi

My second article based on Norbert Möhring's HelloWidget tutorial, but i think it's easier. :) It will look like this:


xmas widget

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How to disable a button on an appwidget?

Wed, 03/03/2010 - 10:18 | by gabor

Would you like to disable a button on an appwidget?
As far as I know it can not be done, since the appwiget UI manipulation is limited by the methods of the RemoteViews class.

But if you insist to do that there is a way to make it look like the button were disabled!

RemoteViews can't manipulate a buttons enabled/disabled state, but it can modify its visibility. So the trick is to have two buttons, the real one, and an other which is designed to look like the real one in disabled state, and change witch one is visible.

Lets see a simple example:
We want to have two buttons on the widget, a stop and a start button in order to stop and start some kind of functionality. Once we have started it, we can not start it agin, until we stopped it and vica versa, so we want to disable the button which can not be used right now.

The XML definition of the buttons can be like this:

  1. <Button android:id="@+id/startbutton" android:text="Start" android:visibility="visible"></Button>
  2. <Button android:id="@+id/startbutton_disabled" android:text="Start" android:clickable="false" android:textColor="#999999" android:visibility="gone"></Button>

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Data Storage tutorial, basic samples are included

Mon, 03/01/2010 - 04:13 | by bence

    Data Storage Methods

  • Preferences
    • Preferences is a lightweight mechanism to store and retrieve key-value pairs of primitive data types.
     
  • Files
    • You can store your data in files on your mobile phone, or in a removable storage medium.
     
  • Databases
    • Android Api supports SQLite databases. All databases, SQLite and others, are stored on the device in /data/data/package_name/databases.
     
  • Network
    • You can also use the Internet to store and receive data, whether it's an SQLite database, or just a simple textfile.

Introducing the Android Emulator, managing Android Virtual Devices (AVD)

Tue, 02/23/2010 - 16:20 | by gabor
The emulator available in the Android SDK is not just a tool that allows you to easily test applications without having to install it to a real device, or even having one. With the proper configuration it is possible to test situations which are hardly reproduced on a physical one.
 
After installing the android plugin and SDK in eclipse an icon is automatically placed on the toolbar to quickly access the Android SDK and AVD (Android Virtual Device) manager.
 
eclipse

You can create multiple AVDs with different parameters:

sdk

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How to set up Eclipse with Android SDK on Ubuntu linux 9.04/9.10 (updated)

Fri, 02/19/2010 - 08:59 | by jozsi

In my first tutorial i will show you how to set up Eclipse 3.5 with Android Development Tools (ADT) on Ubuntu 9.04.

Before we can install the Android SDK, we must install Java. First we open a new terminal window (Applications > Accessories > Terminal).

To install Java, type:

sudo apt-get install sun-java6-bin 

If you are on a x86_64 system, you also must install ia32-libs:
 

sudo apt-get install ia32-libs

For Ubuntu 9.10 users:

Install eclipse from apt-sources, so open a terminal, then:

sudo apt-get install eclipse

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How to set location on emulator

Thu, 01/07/2010 - 05:48 | by akos

emulatorYou have two options if you would like to set the location on the emulator. For both options, you start with starting the emulator first.

Option 1: using DDMS

  • go to your android/tools directory, and launch the DDMS tool
  • select the Emulator Control Tab
  • fill the Location Controls fields with the longitude and latitude values
  • press the Send button

Option 2: using telnet

  • open a command shell
  • conect to the emulator with the command: telnet localhost <port>
  • to enter a fixed location execute the command:
    geo fix <longitude> <latitude> [<altitude>]

For more information visit Location and Maps on the Android Developers page.

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How to debug a Service?

Sat, 12/12/2009 - 09:47 | by akos


debugIntroduction

When you start a project with a service in it in debug mode, and you placed a breakpoint in a method of the service, the debugger will not stop. 

Solution

The solution that works in almost all situation is to wait declaratively in the code for the debugger to attach. To do this, you have to make a call to:

  1. android.os.Debug.waitForDebugger();

The breakpoint can be inserted at any line after this call. 

As a complete example, the SoftKeyboard tutorial is enhanced with the call above:

  1. public class SoftKeyboard extends InputMethodService
  2.         implements KeyboardView.OnKeyboardActionListener {
  3.        
  4.     @Override
  5.         public void onConfigurationChanged(Configuration newConfig) {
  6.         Log.d("SoftKeyboard", "onConfigurationChanged()");
  7.  
  8.         /* now let's wait until the debugger attaches */
  9.         android.os.Debug.waitForDebugger();
  10.        
  11.         super.onConfigurationChanged(newConfig);
  12.        
  13.         /* do something useful... */
  14.                
  15.         }

As you can see in the code, the first call in the method is a call to the logger, with which we can see in the Log output when our method was called. This can be an other way of tracking our method calls, without the need to stop at a breakpoint. But usually this is not enough for detailed debugging.
Then the second statement waits for the debugger to attach, as it is also noted in the comment. After this line the breakpoint can be inserted anywhere in the method.

Debugging a Service in case an Activity is also part of the application is even easier. In that case the activity has to be started first, then the debugger is able to stop at the breakpoint in the service as well, without the need of an explicit waitForDebugger() call.
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