Layout description:

Linear Layout: The LinearLayout arranges views in a single column or single row.  Child views can either be arranged vertically or horizontally which can be specified in the attributes of Linear Layout.

Linear Layout

Absolute layout: The AbsoluteLayout lets you specify the exact location of its  children by managing its position attribute. Google declared the AbsoluteLayout element is deprecated, recently. So start avoiding usage of Absolute Layout in you development.

android:layout_x=”120px”
android:layout_y=”110px”

Absolute Layout

Relative Layout: As the name signifies, the RelativeLayout lets you specify how child views are positioned  relative to each other. Following attributes are used to manage the positions of the elements in the layouts.

android:layout_alignLeft = “@+id/widget”
android:layout_alignTop = “@+id/widget”
android:layout_alignBottom = “@+id/widget”
android:layout_alignRight = “@+id/widget”

android:layout_alignParentLeft=”true|false”
android:layout_alignParentTop=”true|false”
android:layout_alignParentBottom=”true|false”
android:layout_alignParentRight=”true|false”

android:layout_below=”@+id/widget”
android:layout_above=”@+id/widget”

Relative Layout

TableLayout: The TableLayout groups views into rows and columns. You use the <TableRow> element to designate a row in the table. Each row can contain one or more views. Each view you place within a row forms a cell. The width for each column is determined by the largest width of each cell in that column.

Table Layout

FrameLayout: The FrameLayout is a placeholder on screen that you can use to display a single view. Views that you add to a FrameLayout is always anchored to the top left of the layout.

ScrollView: A ScrollView is a special type of FrameLayout in that it allows users to scroll through a list of views that occupy more space than the physical display. The ScrollView can contain only one child view or ViewGroup, which normally is a LinearLayout.

Scroll View

Note: Do not use a ListView together with the ScrollView. The ListView is designed for showing a list of related information and is optimized for dealing with large lists.

.

How to Install .APK files on your Android Mobiles

APK applications are basically Android package applications which is suitable for the installing the application specifically for Android users. If you are struggling with the installation of the .apk file on your phone, then you have reached to the right place. There are two ways to applications on your Android phones:

1. The first way is by installing applications through the online Android Market.
2. The second way is to manually install APK applications on you phone (Developers usually use this method for testing their application before they publish it in the Android Market).

To install the application from Android Market:
You can easily download the application using your android device in the steps given below:

1.  Go to ‘Market’ on your Android-powered device.
2. Select ‘Search’.
3. Enter the keyword of the application you are looking for into the search field.
4. You will be presented with the list of providers. Choose your desired application from the list.
4. Once you have found your application, touch to install.
5. Follow the onscreen instructions to proceed with the installation.

To manually install APK applications on your Android phone do the following:

1. Copy the APK file you want to install to your phone’s memory card and insert the card into your Android phone.
2. Go to Android Market and search for the Apps Installer application.
3. Open it and click on the Install button.
4. After it is installed, just open it. It will show you all the APK files stored directly in the root directory of your memory card.
5. Just click on the application you want to install and it will be installed.

How to Remove Applications:

Uninstall an applications that you installed using the Android Market is ever more simple, just follow the steps:

1. Open the Google Android Menu.
2. Go to the Settings icon and select Applications.
3. Next, click on Manage.
4. You will be presented with a list of applications you have installed.
5. Select the application you want to uninstall, and click the Uninstall button.

History of Android – Mobile Operating System

Android is a operating system used for mobiles which has been developed by Google Inc and is based upon a modified version of the Linux kernel. It was initially developed by Android Inc. (a firm purchased by Google). According to statictics available, unit sales for Android OS smartphones ranked first among all smartphone OS handsets sold in the U.S. in the second quarter of 2010, at 33%. BlackBerry OS is second at 28%, and iphone  is ranked third with 22%.

Android Logo

Android has developed large community of developers writing application programs that extend the functionality of the devices. There are currently over 100,000 apps available for Android, which makes it the second most popular mobile development environment.Developers write managed code in the Java language, controlling the device via Google-developed Java libraries.

The unveiling of the Android distribution on 5 November 2007 was announced with the founding of the Open Handset Alliance, a consortium of 78 hardware, software, and telecom companies devoted to advancing open standards for mobile devices. Google released most of the Android code under the Apache License, a free software and open source license.

The Android operating system software stack consists of Java applications running on a Java based object oriented application framework on top of Java core libraries running on a Dalvik virtual machine featuring JIT compilation. Libraries written in C include the surface manager, OpenCore media framework, SQLite relational database management system, OpenGL ES 2.0 3D graphics API, WebKit layout engine, SGL graphics engine, SSL, and Bionic libc. The Android operating system consists of 12 million lines of code including 3 million lines of XML, 2.8 million lines of C, 2.1 million lines of Java, and 1.75 million lines of C++.

Android System Architecture

History

In July 2005, Google acquired Android, Inc., a small startup company based in Palo Alto, California, USA. Android’s co-founders who went to work at Google included Andy Rubin (co-founder of Danger), Rich Miner (co-founder of Wildfire Communications, Inc.), Nick Sears (once VP at T-Mobile),and Chris White (headed design and interface development at WebTV). At the time, little was known about the functions of Android, Inc. other than that they made software for mobile phones. This began rumors that Google was planning to enter the mobile phone market.

At Google, the team led by Rubin developed a mobile device platform powered by the Linux kernel which they marketed to handset makers and carriers on the premise of providing a flexible, upgradable system. It was reported that Google had already lined up a series of hardware component and software partners and signaled to carriers that it was open to various degrees of cooperation on their part.More speculation that Google would be entering the mobile-phone market came in December 2006. Reports from the BBC and The Wall Street Journal noted that Google wanted its search and applications on mobile phones and it was working hard to deliver that. Print and online media outlets soon reported rumors that Google was developing a Google-branded handset. More speculation followed reporting that as Google was defining technical specifications, it was showing prototypes to cell phone manufacturers and network operators.

Source Wiki