Develop Reference

Support for 8" and 9" tablets

Quoting Supporting Multiple Screens | Android Developers
320dp: a typical phone screen (240x320 ldpi, 320x480 mdpi, 480x800
hdpi, etc).
480dp: a tweener tablet like the Streak (480x800 mdpi).
600dp: a 7” tablet (600x1024 mdpi).
720dp: a 10” tablet (720x1280 mdpi, 800x1280 mdpi, etc).
Now I am building somewhat of a news reader app and for 7" portrait, the app is single pane; 7" landscape, dual pane (ie headlines on the left and details on the right). For both 10" portrait and landscape, it's dual pane.
From roaming the web, I've discovered that there are tablets that falls between 7" and 10". And from my understanding, any device that is in this range will use 7" layouts.
But I want devices that's at least 8" to display two panes.
So my question is, is my approach right and how do I get the dp values of tablets at least 8" (just as 7" is 600dp and 10" 720dp)?

List of Android aspect ratios?

I'm developing a game for mobile devices and have come to the point where I need to adapt it to different aspect ratios.
I've looked around for the common Android aspect ratios but most resources only list the DPI value.
Anyone know any resources I may have missed, or might happen to know the common aspect ratios off the top of their head?

Typically I'm not a fan of providing links as answers, but there is a community wiki here on SO that is maintaining a list of Android aspect ratios. It contains 30+ devices so far.
Found here: Is there a list of screen resolutions for all Android based phones and tablets?

320dp: a typical phone screen (240x320 ldpi, 320x480 mdpi, 480x800 hdpi, etc). = 3:4
480dp: a tweener tablet like the Streak (480x800 mdpi). = 3:5
600dp: a 7” tablet (600x1024 mdpi ~= 640x1024). 10:16
720dp: a 10” tablet (720x1280 mdpi, 800x1280 mdpi, etc). 9:16
from: http://developer.android.com/guide/practices/screens_support.html
also: http://en.wikipedia.org/wiki/Comparison_of_Android_devices

Android values folder to different display sizes

Have declared next values folders.
values
values-sw320dp (... to 4'')
values-sw480dp (5'' to 5,5'')
values-sw600dp (7'' to 10'')
values-sw720dp (10'' to ...)
In each folder have one dimens.xml file with different margins, paddings, etc...
But don´t know what specific values folder need to work with display between 4'' and 5'', specifically 4,65'' and 4,7''.

Check the correct device resolution and follow the charts offered by Android:
http://developer.android.com/guide/practices/screens_support.html
Configuration examples:
To help you target some of your designs for different types of devices, here are some numbers for typical screen widths:
320dp: a typical phone screen (240x320 ldpi, 320x480 mdpi, 480x800
hdpi, etc).
480dp: a tweener tablet like the Streak (480x800 mdpi).
600dp: a 7” tablet (600x1024 mdpi).
720dp: a 10” tablet (720x1280 mdpi, 800x1280 mdpi, etc).
in your case you will have your 4,65'' device in "values-480dp" folder.

What simulator resolution should I use when developing app for Samsung galaxy s2 and galaxy s3?

From what I found, Samsung galaxy s2 has 480x800 resolution and s3 has 1280x720 resolution. So I believe I should ask my graphics designer to provide me hdpi graphics that contain 480x800 background images and to implement same background image in galaxy s3 mobile. Can I use image of size 1280x720 and put it in xhdpi folder so that it can work on s3.
The background image is something which covers whole available area for mobile app. so am I right in this approach ??

Why don't design in both resolutions?
See http://developer.android.com/guide/practices/screens_support.html for more detailed.

You should read Supporting multiple screens. You must define dpi on your emulator. 240 is hdpi, 160 is mdpi and below that are usually ldpi.
Extract from Android Developer Guide link above:
320dp: a typical phone screen (240x320 ldpi, 320x480 mdpi, 480x800 hdpi, etc).
480dp: a tweener tablet like the Streak (480x800 mdpi).
600dp: a 7” tablet (600x1024 mdpi).
720dp: a 10” tablet (720x1280 mdpi, 800x1280 mdpi, etc).

Testing of App on Tablet, Android

I need to create application for Tablet, Android. I never create app fot Tablet, only mobile with Android. How can I create emulator for tablet testing? And 1 thing - I need to know a width of screen for logotype creating - what screen size Tablet have?

For a tablet emulator, just create an AVD using Android 3.0, 3.1 or 3.2 -- this should automatically get you a WXGA (1280x800) screen.
For tablet screen sizes, check out Supporting Multiple Screens: Configuration Examples from the Android documentation:
320dp: a typical phone screen (240x320 ldpi, 320x480 mdpi, 480x800 hdpi, etc).
480dp: a tweener tablet like the Streak (480x800 mdpi).
600dp: a 7” tablet (600x1024 mdpi).
720dp: a 10” tablet (720x1280 mdpi, 800x1280 mdpi, etc).
Most tablets will be in the 7” and 10” range.

First, create fluid layout, so your application will fit any screen size
How to create Liquid Layout in android
http://envyandroid.com/archives/227/stretching-and-spanning-layouts
Second, in android emulator you can change screen size (in settings of ADV)
How do I change screen orientation in the Android emulator?
How to resize the AVD emulator (in Eclipse)?
http://developer.android.com/guide/developing/tools/emulator.html
Third, screen size to set you can get in technical details of tablet
GalaxyPad 1280x800 (http://www.samsung.com/global/microsite/galaxytab/10.1/spec.html)
Motorola XOOM 1280x800 (http://www.motorola.com/Consumers/US-EN/Consumer-Product-and-Services/Tablets/ci.MOTOROLA-XOOM-with-WiFi-US-EN.alt)
and many more, depends on your choice

Sure you can. Just use the android tool to download the SDK for Android 3.0+ (r11 for example) and create an emulator like you would normally.
Note that the 3.0+ emulators like to crash from time to time from my expirience.