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how to add linearlayout inside of linearlayout when application running

I want to know, there is a linearlayout and use that with setContentView function. Also there is a spinner inside of linearlayout. What I want to do is, create a new layout inside of /res/layout folder and add it into layout that I set with setContentView.
Is there anyway or I need to do that programmatically?
EDIT:
I think I couldn't tell.
I have 2 two layouts(ready). I use the first layout with setContentView.For example, there is a buton and if user click that button, I want to add second layout bottom of first layout when application running.

Easiest you do that with include in the xml of your main layout
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical" >
<include layout="#layout/second" />
</LinearLayout>
It´s also possible to do it programmatically, but this way I think it is more clear.
Edit:
To do this programmatically, put this code in listener of the first button.
RelativeLayout view = (RelativeLayout) findViewById(R.id.RelativeLayout1);
Button b = new Button(getApplicationContext());
b.setText("Click me too!");
view.addView(b);
Instead of creating a button (or whatever you want) you can also inflate a premade layout.
LayoutInflater inflater = (LayoutInflater) getSystemService(Context.LAYOUT_INFLATER_SERVICE);
View v = inflater.inflate(R.layout.second, null);
view.addView(v);

I don't think you can change the res folder programmatically. You need to add any layout programmatically only.
Edited:
Get the 2nd layout's instance using findViewById and use setVisibility method to control the layout's visibility.

Why declare buttons in onCreate() in MainActivity.java?

I'm a noob in writing Android app.
The below 2 examples about declaring buttons are all from the Android developer site. (So both of them should be correct and working.)
Example 1: from http://developer.android.com/training/basics/firstapp/building-ui.html
<Button
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="#string/button_send"
android:onClick="sendMessage" />
Example 2: from http://developer.android.com/guide/topics/ui/declaring-layout.html#attributes
<--! (In xml file) Define a view/widget in the layout file and assign it a unique ID: -->
<Button android:id="#+id/my_button"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="#string/my_button_text"/>
//(In java file) Then create an instance of the view object and capture it from the layout (typically in the onCreate() method):
Button myButton = (Button) findViewById(R.id.my_button);
1) So when would I want to assign "Android:id" for my button?
2) What would happen if I assigned "Android:id" for my button in the xml file but I did not declare the button in the "onCreate()" in "MainActivity.java"?

Android:id is just an identifier for your element, in your case its Button. It will not do anything if you didnt use it in the onCreate method. The Id will be useful when you create any listener for the Button. ie., telling your what to do when it is clicked.
You will use something like this.
Button button = (Button) findViewById(R.id.button1);
button.setOnClickListener(new OnClickListener() {
public void onClick(View v) {
// TODO Auto-generated method stub
}
});

Let's go over a few things really quick.
android:id is exactly what it sounds like, its an identification that is used to specify certain Views. Let's say for example you have two buttons on a single layout and you want the buttons to do certain things or maybe you just want to change the text of a button. You would need to initialize the buttons in your Activity onCreate method to do things with them through code. The id is used to differentiate between the views. In our two button example you might give one button the id of buttonOne and the other buttonTwo. This way Android knows which button you are talking about when you refer to them in code. If you assign an id to a button in XML and don't refer to it in code than the button simply does nothing. If you need more info on initializing Views than check out this post on my website. I'm fairly new to Android too so I can explain things to you in a way that you can understand =]
http://www.androidianlabs.com/android-basics-lesson-one.html

Change from one layout view to another and going back?

want to make an Android app that starts with a main layout and when you push a button (called stateButton) that is in this layout the layout changes to a main2 layout containing another button (called boton2), and when you push this one you get back to the first main.
I want to do this in the same activity without creating or starting another one.
Here I show you part of the code:
public class NuevoshActivity extends Activity
implements SensorEventListener, OnClickListener {
private Button stateButton;
private Button boton2;
/** Called when the activity is first created. */
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
this.stateButton = (Button) this.findViewById(R.id.boton);
this.boton2 = (Button) this.findViewById(R.id.boton2);
stateButton.setOnClickListener(this);
boton2.setOnClickListener(this);
}
#Override
public void onClick(View v) {
if(v==stateButton) {
setContentView(R.layout.main2);
}
else if(v==boton2) {
setContentView(R.layout.main);
}
}
}
The mains only have some images, text views and the buttons.
But I've some troubles. Can't it just be as simple as that or what am I missing or what is wrong?

When you use findViewById, you are actually trying to find a view inside the layout you specified by the setContentView. So using setContentView again and again might bring problems when you are trying to check for buttons.
Instead of using a setContentView, I would add the 2 layouts for the screen as child's for a view-flipper which only shows one child at a time. And you can specify the index of which child to show. The benefit of using a view flipper is that you can easily specify a 'in' and 'out' animation for the view if you need an animation when you switch between views. This is a lot cleaner method then recalling setContentView again and again.

The FrameLayout handles this wonderfully... Use this with the <include... contstruct to load multiple other layouts, then you can switch back and forth between them by using setvisibility(View.VISIBLE); and setVisibility(View.INVISIBLE); on the individual layouts.
For example:
Main XML including two other layouts:
<?xml version="1.0" encoding="utf-8"?>
<FrameLayout android:id="#+id/frameLayout1" android:layout_width="fill_parent" android:layout_height="fill_parent" xmlns:android="http://schemas.android.com/apk/res/android">
<include android:id="#+id/buildinvoice_step1_layout" layout="#layout/buildinvoice_step1" android:layout_width="fill_parent" android:layout_height="fill_parent"></include>
<include android:id="#+id/buildinvoice_step2_layout" android:layout_width="fill_parent" layout="#layout/buildinvoice_step2" android:layout_height="fill_parent"></include>
</FrameLayout>
Code to switch between layouts:
findViewById(R.id.buildinvoice_step1_layout).setVisibility(View.VISIBLE);
findViewById(R.id.buildinvoice_step2_layout).setVisibility(View.INVISIBLE);
You will also need to set the visibility of the individual layouts when the activity starts (or in XML) otherwise you will see them both - one on top of the other.

Your boton2 button will be NULL because the definition of the button is in main2.xml.
The only views you will be able to find are the views which are defined in main.xml.

Thanks!!! All the info was usefull to understand a lot of things and as C0deAttack commented I've got troubles with the button on the main2. What I've done is to set View.VISIBLE and View.GONE to the TextViews and Buttons that I wanted in each layout. Thank you very much.

Android: Adding button to custom title bar

I have created a custom title bar as shown in this example
http://staticallytyped.wordpress.com/2011/03/18/android-dynamic-and-custom-title-bars/
"A custom title bar" - half way down.
On some activities I would like to place a button on the right hand side of the titlebar (same as facebook app). I have attempted to add a button to the view as follows, but it doesn't appear.
Custom title bar is displayed as follows
requestWindowFeature(Window.FEATURE_CUSTOM_TITLE);
setContentView(R.layout.maintabhost);
getWindow().setFeatureInt(Window.FEATURE_CUSTOM_TITLE, R.layout.headerbar_include);
Attempting to add button as follows. The button will eventually be an ImageButton and aligned to right of custom titlebar-if I get it working. (just realised I've too many layoutparams now, but this isnt affecting the button display)
LinearLayout layout = (LinearLayout) findViewById(R.id.headerbar);
Button searchButton = new Button(this);
searchButton.setText("info");
LayoutParams layoutParams = new LinearLayout.LayoutParams
(LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT);
searchButton.setLayoutParams(new LayoutParams(
ViewGroup.LayoutParams.WRAP_CONTENT,
ViewGroup.LayoutParams.WRAP_CONTENT));
layout.addView(searchButton, layoutParams);
layout.invalidate();
I could just create another custom titlebar with the button already embedded, but a dynamic solution would be better.
Cheers

First of all, thanks for the link to my blog. Second, let me see if I can't answer that for you. One of the reasons you're having trouble adding another button when you want to add a button is that in that example I left you with no way of retrieving the Title Bar View through the usual channels. Hence, let's fix it (and potentially let me write another blog post this coming weekend.)
Starting with the xml file, add an id attribute:
<LinearLayout
xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:gravity="center_horizontal"
android:orientation="horizontal"
android:id="#+id/title_complex">
<!-- Stuff -->
</LinearLayout>
and here's code to show you how to get that button in there within your Activity (you'll have to add all the flair later):
LinearLayout layout = (LinearLayout) getWindow().findViewById(R.id.title_complex);
layout.addView(new Button(this));
and if you take a look, there's a non-descript button in the Title Bar (like I said, you'll have to add your own flair):
Due note, however, that I can't guarantee that the button will remain or won't remain on subsequent Activities. I haven't investigated it yet but this should get you started. And if you have any more questions, feel free to ask them here (more eyeballs) or on my blog.

Here's one approach to make sure the button(s) remain in the title bar:
How to Create Custom Window Title in Android
Essentially, wrap the android Activity class, and then extend from that new class.

How to load linearlayout dynamically after checking a condition in the class file?

Hey guys please help me out I am new to android application development
Here is the scenerio: This is my layout declaring xml file:
<LinearLayout xxx
<Textview aaa>
</TextView>
</LinearLayout>
//The below LinearLayout I need to display when it meets some condition in java class
i.e if(true) then display the following layout else dont. I can check this condition only after user provides some input.
<LinearLayout xxx
<Textview aaa>
To be displayed after the condition is checked
</TextView>
</LinearLayout>
//following layout is displayed with the first one.
<LinearLayout xxx
<Textview aaa>
</TextView>
</LinearLayout>
Any idea how to do it?

Take a few moments to read the android dev guide. It is worth the time: http://developer.android.com/guide/topics/ui/index.html
Basically, you want to use IDs to refer to the xml layout:
android:id="#+id/myxmlid"
and in your java file:
LinearLayout ll = findViewById(R.id.myxmlid);
if (yourCondition)
mainLayout.add(ll);
I'm assuming that you want to add a widgets to the current layout, rather than just change the text of the current TextView.
Also, this assumes that you want to add more than just a new TextView. If you only need that, you don't need to wrap it in a LinearLayout, which is used to add rows or columns of widgets.

You don't replace your entire layout programmatically just to change the text in one TextView. The way this kind of thing is handled in android, is to include a field in your Activity class for your textview, then instantiate it in your onCreate() method with findViewById() after you've called setContentView() to load the layout so that you can access that TextView's fields and methods.
First, you TextView needs an id in the layout xml.
<TextView android:id="#+id/sometext"
android:layout_width="wrap_content"
android:layout_height="wrap_content" />
Then in your Activity...
TextView mTextView;
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
mTextView = (TextView) findViewById(R.id.sometext);
}
Somewhere else in the program...
public void myMethod(){
mTextView.setText("Text says this now");
}
Hopefully that gets the idea across. Good luck!

Thank Aleadam for suggesting me to read the link. Follwoing was my approach to get the output.
What I did was I assigned my LinearLayout Visibility to "GONE" (android:Visibility="GONE") when declarning the XML, and in the program after the condition is met, changed the visibility to "VISIBLE". (by using layout.setVisibility(View.VISIBLE))