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Adding views in layout from the app in Android

I want to develop an Android app, where start page of the app GUI, will contain 4 vertical layouts in the main layout. Now, in each layout, I want to add buttons/slider dynamically from the app (instead of adding buttons/slider dynamically in the source code). That means, initially all these 4 layouts will be blank and when user will select any button or slider in another layout, to add it in any of this 4 layouts, the button or slider will be added in that layout. User will be able to add max 10 views in any vertical layout and the views can be either button, slider or custom view.
My attempt:
First I tried to create 4 vertical layout under the main layout for startup page and I got succeed.
I also find after searching that its possible to add views dynamically in layouts in android.
dynamically adding a view to activity layout
But most examples, add views dynamically in android by running loops, instantiating the desired view class and then add it in the main layout. Although, in this way, views are added dynamically in the layout, it is done by modifying the source code.
Is it possible to write the source code in a way, so that it can be done directly from the app? So that when user will click on Add a slider in "layout 1", a slider will be added in layout 1 and then again, when the user will click on "Add a button" in layout 1, a button will be added at the end of the slider. User will be able to customize button or slider properties. Also, if the user change the value of the slider, the app will remember its value.
Now, next time, when the app will be opened, those views will be there in the layouts, they will not be deleted and the values will remain unchanged (for example, a ticked check box will remain ticked), so I think I also need some kind of storage or properties manager.
My question is, is it possible to do this in android (because I never seen such apps in android) and if possible, any idea, how can I implement it?
I am totally new to android, so my knowledge is limited but I completed the basic tutorials on android app development and I have plugin development experience in eclipse.
Thanks a lot in. I will highly appreciate your help.

Of course it is possible:
Every layout (like LinearLayout, RelativeLayout etc.) extends the ViewGroup-class, which offers the addView-method.
To add a new view (like a Slider) to one of your layouts, just instantiate it programmatically (via new) in your activity and assign the appropriate LayoutParams to it
To store the state of user added content, it is the easiest to use SharedPreferences - a simple key-value-store which holds data over the application's lifecycle

Yes. This is possible. To create the Views dynamically, you simply have to either extend the class of the View or just say new Button(Context, AttributeSet); (Not only for Button's every View has a constructor that takes an attribute set and a context).
Using Layout.addView() you can add any View to the Layout.
Using SharedPreferences you can indicate what View belongs in what Layout.
If you decide to extend the View's class, make sure not to do too much in it. I tried that once and it just gave me an OOM (OutOfMemory Error) because I had a ton a Views trying to do stuff at the same time.

scroll view for widget

I'm making a widget that contains values from a feed that is pulled from a mysql database. (fortunatley this is not a problem)
My problem is that I need a scrollview within the widget so that the content can be viewed.
Does Anyone know how I can do this? I know I can't have a scrollview in a widget but need an alternative so that content can be scrolled.
Any help would be appreciated

On Android 3.0 and higher, use a ListView, StackView, etc.
On earlier versions of Android, you cannot scroll, period. All you can do is provide a couple of buttons to rotate the contents of the app widget through your data set.

Android layout in java code

i'm making an app that requires indefinite textviews and images. i'm trying to implement a Pulse News app UI but having a hard time implementing one. so i thought of an idea to make a UI like that with the use of textviews, imageview and horizontal scroll view.
textview string values are from parsed xml online and images or the imageviews will be images from a specific directory in the sdcard that my app is using.
can anyone give me ideas how can i do it without using an xml layout or is there any or other options or ways for doing this? thanks...

You can create a viewgroup with one textview and an image. Then it can be added dynamically to your layout many times. This can be done by creating objects in a loop. You can change the content in each viewgroup at the time of inflation.

though i dont know what exactly how pulse new app looks like, but by going through your question (horizontal scroll view in particular) I guess you want to implement a "Gallery" type implementation where in you can swipe left/right on page basis.
If my assumption is correct then you will like to see to ViewPager of android backward compatiblity pkg.

How do you make custom widgets?

When using developing Widgets for Android it seems you are not able to add your own custom View classes to a AppWidgetProvider.
For example I created a custom class which extends View, this works fine when used within an Activity but the moment I add it to a Widget I get a "ClassNotFoundException" because Android seems to only allow a set of certain system widgets to be added.
I have seen some apps which look like they have made there own custom widgets. For example there is one that brings up a radial menu when clicked which shows application shortcuts. How are these being implemented? Is there a work around to using my own custom widget? They seem to have a canvas which they are able to draw on within the widget.
Okay quick example https://market.android.com/details?id=zombiesinthelab.widgets.droidpetwidget&feature=top-paid
So this widget is being done by just drawing ImageViews and updating them periodically opposed to using a canvas to draw the frames?

Android Widgets can only contain Layout-Widgets supported by RemoteViews. See this list:
A RemoteViews object (and,
consequently, an App Widget) can
support the following layout classes:
FrameLayout
LinearLayout
RelativeLayout
And the following widget classes:
AnalogClock
Button
Chronometer
ImageButton
ImageView
ProgressBar
TextView
> Descendants of these classes are not
supported.
Pay attention to the last sentence. You can not change this behaviour, it is hard coded in android.

I have not much idea on how to create widgets but following links can definitely help you:
1) http://developer.android.com/guide/topics/appwidgets/index.html
2) http://developer.android.com/guide/practices/ui_guidelines/widget_design.html

Android Spinner - How to make dropdown view transparent?

I have a custom spinner dropdown xml file in /res/layout/:
spinner_view_dropdown.xml:
<?xml version="1.0" encoding="UTF-8"?>
<TextView xmlns:android="http://schemas.android.com/apk/res/android"
android:id="#+id/spinner_item_dropdown"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:background="#android:color/transparent"
style="#style/spinner_item_dropdown" />
I'm setting the spinner dropdown via java:
// "Spinner", aka breadcrumbs
Spinner spin = (Spinner) findViewById(R.id.breadcrumb_dropdown);
ArrayAdapter adapter = ArrayAdapter.createFromResource(this, R.array.breadcrumb, R.layout.spinner_view);
adapter.setDropDownViewResource(R.layout.spinner_view_dropdown);
spin.setAdapter(adapter);
// /"Spinner"
Unfortunately, a white background still exists on the spinner popup regardless if I set the background to transparent.
How do I fix this?

You can override the style for the dropdown, and the dropdown item by using a Theme in your app that inherits from one of the Android themes, then override the
android:dropDownSpinnerStyle, or android:spinnerDropDownItemStyle, and even the android:dropDownListViewStyle attribute of the theme, pointing to your own custom style instead of the Android style that is defined in their theme. I created a fully customized spinner this way, with a transparent button AND dropdown. I even got rid of the dropdown list dividers, and set my own spacing for the dropdown items when I built the tablet app for Fandango (take a look at the sort movies spinner on the main page of the app).
Everything in Android is customizable, you just have to know where to look. ;-)

Try setting on the spinner this:
android:popupBackground="#android:color/transparent"

The layout you're defining is only used for an entry of your drop-down, not the drop-down itself. So setting the background to transparent won't have any effect on its background. But even if it would, setting the background to transparent would still have no effect, because a TextView (actually I believe any view) has a transparent background by default.
That being said, the right question would be: can you provide a custom layout for an entry's parent view (which is probably a List)? As far as I know, the answer is no, unfortunately.

Try
android:cacheColorHint="#00000000"
to get transparency.
I dont know if it works for you but there is a post
http://android-developers.blogspot.com/2009/01/why-is-my-list-black-android.html
that explains why the moving parts of a list appear in the background color.
Maybe its the same issue with your spinner.

It's a bug in 1.5 I think, see here
http://www.symsource.com/index.php?view=article&id=418&option=com_content&format=pdf
Run it in a 1.6 emulator or device, does it still stay white?
I actually came here looking for an approach to this, I suspect this may involve manually writing to the canvas or something like that.
Any ideas.
P.S. Accidentally posted when I thought I was logged in, anyone know how to get rid of the anonymous comment? Maybe an admin could fix this?