ANDROID LAYOUTS

An Android layout is a class that handles arranging the way its children appear on the screen.  Anything that is a View (or inherits from View) can be a child of a layout. All of the layouts inherit from ViewGroup (which inherits from View) so you can nest layouts.  You could also create your own custom layout by making a class that inherits from ViewGroup.

The standard Layouts are:

                         AbsoluteLayout

                         FrameLayout

                         LinearLayout

                         RelativeLayout

                         TableLayout

AbsoluteLayout

 AbsoluteLayout is based on the simple idea of placing each control at an absolute position.  You specify the exact x and y coordinates on the screen for each control.  This is not recommended for most UI development (in fact AbsoluteLayout is currently deprecated) since absolutely positioning every element on the screen makes an inflexible UI that is much more difficult to maintain.  Consider what happens if a control needs to be added to the UI. You would have to change the position of every single element that is shifted by the new control

Exaple:

<AbsoluteLayout xmlns:android="http://schemas.android.com/apk/res/android"

    android:layout_width="fill_parent"

    android:layout_height="fill_parent">

    <Button

      android:id="@+id/backbutton"

      android:text="Back"

      android:layout_x="10px"

      android:layout_y="5px"

      android:layout_width="wrap_content"

      android:layout_height="wrap_content" />

    <TextView

      android:layout_x="10px"

      android:layout_y="110px"

      android:text="First Name"

      android:layout_width="wrap_content"

      android:layout_height="wrap_content" />

    <EditText

      android:layout_x="150px"

      android:layout_y="100px"

      android:width="100px"

      android:layout_width="wrap_content"

      android:layout_height="wrap_content" />

   

</AbsoluteLayout>

FrameLayout:

•FrameLayout is designed to display a single item at a time. You can have multiple elements within a FrameLayout but each element will be positioned based on the top left of the screen. Elements that overlap will be displayed overlapping. I have created a simple XML layout using FrameLayout that shows how this works.

ex:

<FrameLayout

  android:layout_width="fill_parent"

  android:layout_height="fill_parent"

  xmlns:android="http://schemas.android.com/apk/res/android">

  <ImageView

  android:src="@drawable/icon"

  android:scaleType="fitCenter"

  android:layout_height="fill_parent"

  android:layout_width="fill_parent"/>

  <TextView

  android:text="Learn-Android.com"

  android:textSize="24sp"

  android:textColor="#000000"

  android:layout_height="fill_parent"

  android:layout_width="fill_parent"

  android:gravity="center"/>

</FrameLayout>