Mobile Computing LECTURE # 2

Transcription

1 Mobile Computing LECTURE # 2

2 The Course Course Code: IT-4545 Course Title: Mobile Computing Instructor: JAWAD AHMAD Address: Web Address: Term (Semester): Spring 2018 Duration: 15/16 Weeks

3 Introduction to Java Language

4 What is Java? Java is a computer programming Language just like C C++ Developed by Sun Microsystems in around 1990s and now Oracle corporation. Converts Human understandable instructions to Machine understandable instructions

5 Java Program Flow

6 Java Program Components Java Code (.java) Set of instructions Written by following Language rules A programmer writes these instructions Also called Source Code Saved in a file with.java extension Can be written in any text Editor Notepad

7 Java Program Components Java Compiler (javac) Reads Java Source Code Converts into Computer Readable Form Checks for Errors Makes sure all the instructions are in proper order Creates Java Byte Code Java Source Code (.java) Java Compiler (javac) Java Byte Code

8 Java Program Components Java Byte Code (.class) Set of instructions compiled by Java Compiler These are instructions readable by JVM (Java Virtual Machine) Normally not editable in normal Text Editors like Notepad Special Editors are used Java Byte Code Editor Programmer does not need to understand Java Byte Code Java Source Code Java Compiler Java Byte Code

9 Java Program Components Java Virtual Machine (JVM) It s a platform independent execution environment It is actually a program that reads other program Normally Java Byte Code It provides a runtime environment for Java Byte Code According to Sun Microsystems, there are almost 5.5 Billion JVM Enabled devices Java Byte Code Java Virtual Machine Output of a Program

10 Object Oriented Programming Language (OOP)

11 Object Oriented Programming OOP has Objects Classes Methods Encapsulation Inheritance Polymorphism

12 EngineStart() Object in OOP Everything is an Object An Object Knows something Does something Drive() Vehicle type color name EngineStop() Knowing something is Instance Variables Doing something is Methods Variables Turn() Methods

13 What is a Class? Classes are used to create an Object It tells JVM how to make an Object

14 How to create a Class? Modifier Identifier Class Name public class HelloWorld { Return Type Method Name Method Arguments public static void main (String[] args) { Part of Class not Object Print output to console } } System.out.println("Hello World!"); String to be displayed

15 Encapsulation Makes the data private Uses Getters and Setters Others can use only the data you want them to use Access Modifiers Private Public protected

16 Some other Objects Button Label Color getlabel() getcolor() setlabel() setcolor() click() Variable Method Song Title Duration gettitle() getduration() settitle() setduration() play() Programmers normally have getter and setter methods for variables Getters Setters getlabel() setlabel() getcolor() setcolor() gettitle() settitle() getduration() setduration()

17 Inheritance Subclass inherit from Superclass Subclass will inherit Variable Methods Subclasses can override the methods of superclass Make their own versions of methods Backward inheritance is not possible Superclass cannot extend methods, variable from subclass

18 Inheritance Super class Sub class

19 Polymorphism

20 Polymorphism

21 Abstract Classes

22 Abstract Classes Some classes should not instantiate Abstract classes should always be extended We will never create an object of that class We can however make reference for that class Some general classes have no definition as object instantiation Vehicle Animal abstract class Vehicle { public void drive() { abstract public class Vehicle { public void drive() { } } } }

23 Abstract Classes abstract public class Vehicle { public void drive() { } } public class MakeVehicle { public void start() { Vehicle vehicle; public class MakeVehicle { public void start() { Vehicle vehicle; } vehicle = new car(); } } vehicle = new vehicle(); }

24 Abstract Methods An abstract method has no body An abstract method can reside in Abstract class only Non-Abstract Classes cannot carry Abstract methods Abstract class can carry both Abstract and Non-Abstract methods abstract public class Vehicle { public void drive() { Non- Abstract Method } } public abstract void idle(); Abstract Method

25 Multiple Inheritance not allowed in Java

26 Multiple Inheritance not allowed in Java

27 Interfaces in Java Replace class with interface

28 Interfaces in Java A class can implement multiple interfaces

29 Introduction to Android Development

30 What is Android? Its an OS for mobile phones It is a modified form of Linux It runs on Linux Kernel 3.18 Bought by Google in 2005 Android is open source Source Code is available at Different hardware vendors can build their devices and run Android on them

31 Android Versions

32 Android Features Storage SQLite Connectivity GSM CDMA LTE Wi-Fi WiMax Messaging Multitouch Multitasking

33 Android Architecture

34 Android Architecture Linux Kernel Android runs on Linux Kernel 3.18 A Kernel is collection of programs that helps in interaction of software and hardware. These programs are called drivers. Android because of its foundation on Linux Kernel contains all the basic functionality of Linux e.g. Memory Management. A device with certain hardware should have a proper driver in the Linux Kernel to work properly Bluetooth will not work until the driver is available for that hardware.

35 Android Architecture Libraries Android contains some core libraries which help build different other libraries. Some of the most important libraries are Media Framework Contains all the codes for media WebKit It is a browser engine that runs HTML content SQLite Handles storage of data

36 Android Architecture Android Runtime Dalvik Virtual Machine It is a virtual machine like JVM. It does not run.class file, instead it runs.dex files These files are created from.class files at compilation time. Multiple instances of DVM can run simultaneously. Core Libraries It contains different libraries from Java SE and Java ME

37 Android Architecture Application Framework As a developer we directly interact with this layer. This layer contains libraries which provide basic functionality for android like call, messaging and resource management etc. Some of them are Activity Manager It takes care of the activity life cycle Location Manager It handles the location

38 Android Architecture Applications Based on all the previously mentioned layers, our applications will be available at Applications Layer. Almost all the applications are handled at this layer. Default apps also fall in this category Some of the default apps are Phone Messaging Mail

39 Android Smart Phones Galaxy S II Motorola Atrix 4G, HTC EVO 4G

40 Android Tablets Samsung Galaxy Tab 10.1 Asus Eee Pad Transformer TF101

41 Android EBook Readers Barnes and Noble s NOOK Color Amazon s Kindle Fire

42 Android Based TV Scandinavia Android TV

43 Mashup Compatibility Combination of two or more service to create an App. Geolocation + Social networking Geolocation + Gaming Camera + Geolocation Contacts + Maps

44 Components of Android Programming Activities Android Application are composed Activity of Activities Each Application will have at least one Activity Activities are like container Code Hello World! User Interface Its like Form for Windows in Vb.net

45 Components of Android Programming Intents Intent = Action + Data It can be transition between two activities It can be launching an app from one app It s a message to Android System to tell app will do something

46 Components of Android Programming Cursorless Control Unlike PCs, no cursor on screen Fingers are used to perform Screen Actions Multitouch gestures Zooming Dragging Long Press right click

47 Components of Android Programming Views and Widgets View is a rectangular area on screen for drawing Menu Context Menu Widgets are advanced UI Controls Buttons Checkboxes DatePickers etc.

48 Components of Android Programming Background Service Service is a program that doesn t need to have a UI A background service runs in the background Antivirus application in windows is a background service Alarm app runs in background for mobile phones

49 Android Hardware Tools

50 Google APIs Android can do more than Calls and Messages It can help in navigating It can help in showing a friend on map

51 Android in Cloud Information can be stored in Cloud Information can be retrieved from Cloud

52 Android Development Tools

53 Requirements Any PC running Windows Mac OS X Linux Android Studio JDK