Mobile Application Development Notes

 Fillups:

1. APK stands for Android Application Package

2. Android is an Linux-based mobile operating system

3. Android is mainly developed for touchscreen devices, cell phones, and tablets.

4. Android is based on Java, with some C and C++ libraries.

5. API stands for Application programming interface.

Questions and Answers :

Q1.  Feautres of android operating system are as follow :-

Near Field Communication : NFC is a wireless technology by which you can quickly send your data to different devices with just one click.

Multiple Language Support : Android's Multilingual capability enables users to switch between different languages. 

Multi-tasking : Multitasking by Android Operating System can make phone users use various applications simultaneously.

Connectivity : Android devices provide a wide range of connectivity possibilities. WiFi, Bluetooth, Hotspots, CDMA, and GSM are some examples.

Customizability : It enables the user to personalize your device completely. Users can use Widgets that help display necessary elements on their home screen.

Storage and battery optimization : Customers can choose the amount of memory they need and expand.

Security : Special functions like camera and microphone require the user's permission. Built-in data encryption features provide additional security protection for user data

Q2. Discuss about fragments and intents.

Fragments: As there are a lot of android devices with different resolutions, its a bit tough to handle all of those, that’s where fragments come handy. We can combine 2 or more fragments and show them in an activity. A Fragment is a component that is used by an activity.

Even though it is used by an activity, it has its own lifecycle.

There are also some different fragments which you can extend: DialogFragment, ListFragment, PreferenceFragment.

Intents :

Intent is one of the most important and most used app component of an android application.

Using Intents, you call to other app components or to other activity or also call other applications on your phone.

Intents are two types:

Explicit Intents where you call another activity or something with a class name. For instance, you can call another activity when some action happened in one activity. So you here explicitly specifies which activity to call.

Implicit Intents where we do not specify a class name but specify some sort of action, which can be handled by some other inbuilt apps or some other apps. For instance, you may want to open a camera, showing a map, sending emails etc. Here you don’t directly call camera app or map app, you will just specify the action.

Q3. Difference between Table Layout and Frame Layout.

Table Layout : It is a ViewGroup subclass that is used to display the child View elements in rows and columns. Following is the pictorial representation of table layout in android applications.

In android, TableLayout will position its children elements into rows and columns and it won’t display any border lines for rows, columns or cells.

The TableLayout in android will work same as the HTML table and the table will have as many columns as the row with the most cells. The TableLayout can be explained as <table> and TableRow is like <tr> element.

Frame Layout : In android, Framelayout is a ViewGroup subclass that is used to specify the position of View instances it contains on the top of each other to display only single View inside the FrameLayout.

In simple manner, we can say FrameLayout is designed to block out an area on the screen to display a single item. Following is the pictorial representation of frame layout in android applications.

In android, FrameLayout will act as a placeholder on the screen and it is used to hold a single child view.

In FrameLayout, the child views are added in a stack and the most recently added child will show on the top. We can add multiple children views to FrameLayout and control their position by using gravity attributes in FrameLayout.

Q4. Difference between basic and picker view.

Basic view : Commonly used views such as the TextView, EditText, and Button views.

Picker view : It displays one or more wheels that the user manipulates to select items. Each wheel — known as a component — has a series of indexed rows representing the selectable items. Each row displays a string or view so that the user can identify the item on that row. Ex- Selecting date from a month of calender.

Q5. Short note on Android Stack.

The Android software stack generally consists of a Linux kernel and a collection of C/C++ libraries that are exposed through an application framework that provides services, and management of the applications and run time.

Android Architecture: Layers in the Android Stack

Linux Kernel Layer.

Native Layer.

Application Framework Layer.

Applications layer.

Q6. Database cursor and its types are as follow :

A database cursor is used to referred to a program to fetch and process the rows returned by the SQL statement, one at a time. It is to point to a single row of the result fetched by the query. We load the row pointed by the cursor object. By using cursor we can save lot of ram and memory.

Types of database cursor :

1. Implicit Cursor :  The implicit cursors are automatically generated by Oracle while an SQL statement is executed, if you don't use an explicit cursor for the statement.gram to fetch and process the rows returned by the SQL statement, one at a time.

2. Explicit Cursor : The Explicit cursors are defined by the programmers to gain more control over the context area. These cursors should be defined in the declaration section of the PL/SQL block. It is created on a SELECT statement which returns more than one row.

Q7. Role of GPS in Android devices.

GPS is used in a variety of applications, including navigation, tracking, and location-based services. Some common uses of GPS on a mobile phone include: Navigation: GPS can be used to provide turn-by-turn directions to a destination, helping you find your way to a new location or back home.

 

Q8. What is persisting data in SQLite.

Persistent data is data which you want to be available even after you fully close and restart your app. The three most common ways to safe this data localy is by using SharedPreferences, a local database or the file system (store data as a file)