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Many layouts in Scroll View in android

I want to have 3 layouts in my ScrollView but when I add them it actually doesn't scroll. I tried to put all layouts in different files, then include them, tried to put them in ListView and it doesn't work too. In this option, when I put in ScrollView the LinearLayout and there include the rest of the layouts the application show nothing. That's probably becouse I don't know how to refer to that nested layouts... This is my XML:
activity_main.xml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical"
android:layout_width="match_parent"
android:layout_height="wrap_content"
>
<ScrollView android:layout_width="match_parent" android:layout_height="match_parent">
<LinearLayout android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="vertical"
>
<include layout="#layout/first"/>
<include layout="#layout/second"/>
<include layout="#layout/third"/>
</LinearLayout>
</ScrollView>
</LinearLayout>
#EDIT views included (all are the same so I put just one):
<RelativeLayout
xmlns:android="http://schemas.android.com/apk/res/android"
android:id="#+id/first"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
>
</RelativeLayout>
And in the main activity I put the objects into layouts like this:
setContentView(R.layout.activity_main);
RelativeLayout first = (RelativeLayout) findViewById(R.id.first);
RelativeLayout second = (RelativeLayout) findViewById(R.id.second);
RelativeLayout third = (RelativeLayout) findViewById(R.id.third);
...some code creating views...
first.addView(myView1);
second.addView(myView2);
third.addView(myView3);

Need to put fix size in included layout, for example:
<RelativeLayout
xmlns:android="http://schemas.android.com/apk/res/android"
android:id="#+id/first"
android:layout_width="match_parent"
android:layout_height="300dp"
/>
I don`t understand why do you need to add view manually when you already added it to the layout.
You should also eliminate top Linear Layout since there is no use of it.

Android pass image to another xml file

I have an image in my main.xml as follows
<ListView
android:id="#android:id/list"
android:layout_width="fill_parent"
android:layout_height="wrap_content"/>
<ImageView
android:id="#+id/imageView1"
android:layout_width="70dp"
android:layout_height="70dp"
android:contentDescription="#string/hello"
android:maxHeight="70dp"
android:maxWidth="70dp" />
but I need to pass it to another xml file. Is this possible?

In your case you are having data reference.

Yes, its possible. Exists a tag called in android that you can "include" another android xml layout in other android xml file. I put a example using your main.xml
In layout2.xml ....
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:orientation="vertical" >
<include layout="#layout/main"/>
</LinearLayout>
More information about this tag, please check it out in the link below.
http://developer.android.com/training/improving-layouts/reusing-layouts.html

include tag in android manifest xml

how can we use include tag in layout.xml. Also by using this what are the features we can implement.
<include> </include>

include is normally used to reuse the layouts if suppose you are doing app which consists of common header and footer layouts you can use like this
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent" android:layout_height="fill_parent"
android:background="#drawable/bg1" android:orientation="vertical">
<!—header layout->
<include android:id="#+id/container_header_lyt"
android:layout_height="wrap_content" android:layout_width="fill_parent"
layout="#layout/main" />
<!—contains other views in layout>
</LinearLayout>
in this case you are reusing layout main

But according to http://developer.android.com/guide/topics/manifest/manifest-intro.html no such tag is allowed

Accessing Android views on nested layouts

I have trouble accessing Views from a layout that is included in another layout.
Please take a look at this picture:
http://dl.dropbox.com/u/3473245/layout_includes.png
How do I access the 4 text views programmatically?
Its probably something really simple that I'm missing.
Thank you very much!

You can do as follows:
main.xml
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:orientation="vertical" >
<include android:id="#+id/item_base_lang" layout="#layout/dictionary_list_item" />
<include android:id="#+id/item_learn_lang" layout="#layout/dictionary_list_item" />
</LinearLayout>
dictionary_list_item.xml
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical"
android:layout_width="fill_parent"
android:layout_height="wrap_content" >
<TextView
android:id="#+id/dictionary_list_item_text_header"
android:layout_width="fill_parent"
android:layout_height="wrap_content" />
<TextView
android:id="#+id/dictionary_list_item_text_content"
android:layout_width="fill_parent"
android:layout_height="wrap_content" />
</LinearLayout>
To set the text programmatically:
((TextView)findViewById(R.id.item_base_lang).findViewById(R.id.dictionary_list_item_text_header)).setText("item_base_lang_header");
((TextView)findViewById(R.id.item_base_lang).findViewById(R.id.dictionary_list_item_text_content)).setText("item_base_lang_content");
((TextView)findViewById(R.id.item_learn_lang).findViewById(R.id.dictionary_list_item_text_header)).setText("item_learn_lang_header");
((TextView)findViewById(R.id.item_learn_lang).findViewById(R.id.dictionary_list_item_text_content)).setText("item_learn_lang_content");
This Android wiki page shows how to use reusable UI components with XML layouts, but it doesn't show how to access nested reusable components from code.
Although it is fairly straightforward, it might be not so clear for those who are pretty new to Android Views.

The following two lines should help you get the languageHeader of both includes. You can do the same for languageText
findViewByid(R.id.activityBaseLangView).findViewById(R.id.languageHeader)
findViewByid(R.id.activityLearnLangView).findViewById(R.id.languageHeader)

import xml into another xml

I have lots of control repeated in my xml (a Button for instance). Is there any possibility to write the Button once in a xml and then import it in all the layout I need it?

You can use
<include layout="#layout/commonlayout" android:id="#+id/id" />
commonlayout.xml should be defined in res/layout where you can add the repeated parts.

As Labeeb P rightly said, it works.
Just want to add that you can also override parameters too:
<include
layout="#layout/commonlayout"
android:id="#+id/id"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_weight="1"
android:layout_marginLeft="2sp"
android:layout_marginRight="2sp"
/>

In addition to those great answers, you can also avoid code duplication by using the <merge> tag, like so:
<merge xmlns:android="http://schemas.android.com/apk/res/android">
<Button
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:text="#string/add"/>
<Button
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:text="#string/delete"/>
</merge>
The <merge> part gets stripped when you include it into other xml. This might help including more than a single Button at a time. See the official documentation.

You can use the default include XML tag to include an external layout:
<include layout="#layout/somelayout" />
This layout should have an outside ViewGroup that encapsulates the content or a merge tag to avoid having to use an unnecessary layout:
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent">
<TextView android:layout_width="match_parent"
android:layout_height="match_parent"
android:text="#string/hello_world" />
</LinearLayout>
<!-- OR -->
<merge xmlns:android="http://schemas.android.com/apk/res/android">
<TextView android:layout_width="match_parent"
android:layout_height="match_parent"
android:text="#string/hello_world" />
</merge>
Also, if you need a better way to include pieces of layout that acts like a container (a custom ViewGroup), you can use this custom ViewGroup. Note that this does not import an XML into another XML file, it inflates the content from the external layout and replaces into the view. It's similar to ViewStub, a "ViewGroupStub" like.
This lib acts as if the ViewStub could be used as following (note that this example does not work! ViewStub isn't a ViewGroup subclass!):
<ViewStub layout="#layout/somecontainerlayout"
inflate_inside="#+id/somecontainerid">
<TextView android:layout_width="match_parent"
android:layout_height="match_parent"
android:text="#string/hello_world" />
</ViewStub>