Question

I want to use a command like this:

ImageView image = (ImageView) findViewById(R.id.x2);

where should I put in the file main.xml the following piece of code?

<ImageView 
    android:id="@+id/x2"
    android:src="@drawable/book"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content" />

Answer 1

Dheeresh Singh is ok.
main.xml:

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent" >

   <ImageView 
          android:id="@+id/x2"
          android:src="@drawable/book"
          android:layout_width="wrap_content"
          android:layout_height="wrap_content" />
</LinearLayout>

If you want to position the image in a different place, you can modify different attributes

 <ImageView 
              android:id="@+id/x2"
              android:src="@drawable/book"
              android:layout_width="wrap_content"
              android:layout_height="wrap_content"
              android:layout_marginBottom="42dp"  <!--for example  -->
              android:layout_marginLeft="25dp"
              android:layout_marginRight="25dp" 
              android:layout_marginTop="25dp"/>

For more information about this, look at the android tutorials

http://developer.android.com/reference/android/widget/ImageView.html (for ImageView attributes)
http://developer.android.com/resources/tutorials/views/index.html (for view info)

Excuse me for my english.
Good Luck!