Develop Reference

What techniques do you think duolingo used to make its lesson list in the app?(pic included)

I'm trying to make the duolingo lesson list for fun because im a big fan of the app, im a beginner programmer.
basically id like your opinion on how you think they did it.
here is what it looks like
https://s-media-cache-ak0.pinimg.com/236x/a3/a8/65/a3a865c47153078e7004b74652af7757.jpg
I think it might be a scroll view and linear layout, then perhaps a class for each icon/progress/name combo that will change based on progress

I think a table layout might be an easier solution.
Check it out here: https://developer.android.com/guide/topics/ui/layout/grid.html

I figured out how to do it, you need to use a scrollView followed by a linearlayout.
Then you can programatically add in relative layouts as rows and in those relative layouts make another square relative layout and in that relative layout you stack up the stuff like image/text/progress

Using Layout - Android

I have a layout, but I need put more views (Buttons, EditText, etc), but how you know, the layout of the ADT is a bit small and I can't to set more views or know where is it, Somebody know How can I set more of these?
Thank you

Android isn't like iOS how you can just position elements with drag & drop.
RelativeLayout will position elements relative to each other and LinearLayout will lay out elements sequentially in a linear fashion, either vertically or horizontally. Both methods are better executed by actually writing the View XML yourself.
I suggest reading this: http://developer.android.com/guide/topics/ui/declaring-layout.html

If you want to actually see what you are adding to your layout without messing with the XML you could maybe change the device that the renderer is using to preview your layout.
I don't know what IDE you're using but in Eclipse and Android Studio you can change the device that your layout preview is rendered on. That way you can see what you're adding as you add it.
Then just make sure to put everything in a scroll view so users can access all the views and widgets you've put in that layout for your activity or fragment or dialog or whatever else it is.

How to place UI elements to the position we want in Android?

I have some buttons, textboxes etc. in my android application, but when i drag them with my mouse in the xml file, their place doesn't change, or changes but they are not placed where i exactly wanted. How can i adjust their positions in the screen?
Thanks

Unfortunatly there is no such thing as absolute positionning in android ( RIP AbsoluteLayout deprecated since years.)
instead you have to position views according to their parents and according to other views in the same parent.
first you have to define wich parent you need ( if you want some viens in a single line go for a LinearLayout. a more custom layout: use a RelativeLayout ...)
then you can drag and drop views inside, but they will always snap a position relative to their parent and/or relative to the other views.
you can of course play with margins.
A list of layout type with some advanced techniques can be found on this page
Hope that helps.

You RelativeLayout as a group layout for your layout so positioning can somewhat easy using mouse.
Best is to arrange them from the xml code. Just Learn about using the Relative layout, LinearLayout and TableLayout

Learn how the XML works. For a LinearLayout, the items come in the order listed. For a RelativeLayout, the items are related by the values of their layout_XXX properties. Then you don't have to worry about the WYSIWYG tool not working.
FYI, the tool bundled with eclipse is extremely buggy. Don't count on whats on there being what's on your phone for anything non-trivial.

Like the others wrote it is easier to edit layout using xml editor. You can read more here http://developer.android.com/guide/topics/ui/declaring-layout.html.

Which layout should I use so my app looks like Google Plus?

I'd like to make a layout similar to the one used in the current version of Google Plus:
I don't know which layout I must use because :
- I can't use a GridView because it doesn't support spanning row.
- I can't use a GridLayout nor LinearLayout because the number of elements to show is dynamic
- I can't use a ScrollView because I want an AdapterView to re-use child elements
- I can use a ListView with two differents cells types but I can't use the built-in OnItemClickListener.
Do you have better ideas than me?
Thank you very much :)

this post suggested that it uses StaggeredGridView . I personally haven't tried it.

You can very well use RelativeLayout for this.
With a single Relative Layout you should be able to create exactly same layout.
Additionally, your content can be dynamically added to Relative Layout pretty easily (by setting proper LayoutParams to the content to be added).

Aligning components at desired positions

Seeking help to design a layout as shown here:
http://docs.google.com/Doc?docid=0AQhgDtGvE2HgZGZ6cmtua185MTd0eGdyZmc&hl=en
The major challenge I face is aligning the components at desired positions. Please refer the three buttons(icons) and the way they are positioned.
Literally, going nuts, thinking how to position those exactly at the desired places.
Any help is much appreciated.
Regards,
Rony

Since you used the Android category, I'm assuming that you're trying to recreate this iPhone layout in Android.
The three buttons would probably be best laid as follows.
Your main layout container would probably be a RelativeLayout, so you can dock things to the top and bottom and lay everything else out in relation to one of its sibling elements. The three button icons (and I'm assuming you're referring to the circular buttons and not the tab bar buttons at the very bottom) would be in a LinearLayout centered within its parent (probably want to use gravity=center_horizontal on the main outer layout) and the individual items would have an equal left and right margin parameters to get the desired spacing (layout_marginLeft, layout_marginRight). You could also make the LinearLayout container of the buttons flush (layout_width=fill_parent) and using android:weight attribute on the outer buttons laying them out towards the center and using a lower weight on the center item. I'd favor the first option, personally.
If you're trying to create relatively complex layouts and any of the above doesn't make sense, go back and read the docs. Layout in Android is very powerful, but you really have to understand the available tools to take advantage of it.