Programming examples: March 2016

When a new android project is created main.xml layout file is generated by default. In Netbeans LinearLayout is default layout.There are six type of layout in android:-

1. Linear Layout

2. Relative Layout

3. Table Layout

4. Absolute Layout

5. Frame Layout

6. List View

7. Grid View

Linear Layout: Android 'LinearLayout' is a view group that aligns all children in single direction either horizontal or vertical. The default orientation is horizontal.

Some of the basic attribute of Linear Layout.

Attributes	Description
android:id	ID which uniquely identifies layout
android:baselineAlign	This is a Boolean value which must be set true or false. It prevents layout from aligning its children baseline.
android:gravity	This specifies how object should position its content on both X and Y axis.
android:orientation	This specifies direction of all objects in layout. It can be either set to horizontal or vertical. Default orientation is horizontal
android:weightSum	Defines the maximum weight sum.
android:background	Sets background image

Example code for Linear Layout

Relative Layout: Android RelativeLayout enables you to specify how child views are positioned relative to each other. The position of each view can be specified as relative to sibling elements or relative to the parent.

Attributes	Description
android:id	ID which uniquely identifies layout
android:gravity	This is a Boolean value which must be set true or false. It prevents layout from aligning its children baseline.
android: ignoreGravity	This indicates what view should not be affected by gravity.

By default, all child views are drawn at the top-left of the layout, position of each view must be defined using the various layout properties available from RelativeLayout.

Example for Relative Layout

Table Layout: Android TableLayout groups views into rows and columns. You will use the <TableRow> element to build a row in the table. Each row has zero or more cells; each cell can hold one View object.

TableLayout containers do not display border lines for their rows, columns, or cells.

Attributes	Description
android:id	This is the ID which uniquely identifies the layout.
android:collapseColumns	This specifies the zero-based index of the columns to collapse. The column indices must be separated by a comma: 1, 2, 5.
android:collapseColumns	The zero-based index of the columns to shrink. The column indices must be separated by a comma: 1, 2, 5.
android:stretchColumns	The zero-based index of the columns to stretch. The column indices must be separated by a comma: 1, 2, 5.

Code for table layout

Absolute Layout: An Absolute Layout lets you specify exact locations (x/y coordinates) of its children. Absolute layouts are less flexible and harder to maintain than other types of layouts without absolute positioning.

Attributes	Description
android:id	This is the ID which uniquely identifies the layout.
android:layout_x	This specifies the x-coordinate of the view.
android:layout_y	This specifies the y-coordinate of the view

1. Create a new android application in Netbeans.
2. Copy your image file to /res/drawable directory
(Note: Name of image file should be in small letter)

3 Open main.xml file and add following line to it.

android:background="@drawable/hd_bg"

Here "hd_bg" is image file name without extension.
Your main.xml file should look like this.

<?xml version="1.0" encoding="utf-8"?>

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

android:orientation="vertical"

android:layout_width="fill_parent"

android:layout_height="fill_parent"

android:background="@drawable/hd_bg"

>

<TextView

android:layout_width="fill_parent"

android:layout_height="wrap_content"

android:text="Hello World, MainActivity"

/>

</LinearLayout>