Android Beginner Lecture 3-4

7/29/2019 Android Beginner Lecture 3-4

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Android Course Lecture-3 and 4

CSDAN0101

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Ramakrishna Reddy KGraduate Student

ME Computer Science


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Agenda App Inventor Tool

Animation Conditional Blocks

Lists Iteration Web services , APIs and Mashing Data Persistent Data

App Inventor Capabilities and Limitations Applications Demo

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Think about it !!

Witricity: (Marin Soljacic)

Wireless electricity

Source: http://www.witricity.com/

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http://www.witricity.com/http://www.witricity.com/http://www.witricity.com/http://www.witricity.com/http://www.witricity.com/http://www.witricity.com/http://www.witricity.com/http://www.witricity.com/


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Animation

In this section, you'll learn how to write a simple animated game and beintroduced to timer events, randomness, and global variables.

Animated Objects App Inventor has two types of animated objects: a Ball and an

ImageSprite .Timer Events To add a timer event, you first add a Clock component to the application in

the Component Designer .Moving an Object Periodically

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Animation

Ball/Image Sprite Events

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Animation

Reacting to Touch and the Ball Reaching an Edge

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Variables


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Animation

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Randomness


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Conditional blocks

This chapter discusses apps that branch to execute different functionsbased on some condition.

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If and Ifelse Blocks


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Conditional blocks

Sample: Calling a random friend from a set of friends.

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Conditional Blocks

Sample: Mastermind

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Lists This chapter describes how to work with lists of data in an App Inventor

application. A list is a variable, but instead of representing a single memory cell, it

represents an array of cells: E.g. : PhoneNumberList

|3219872 |4153297878 |4592371|

Making a List

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Selecting an Item


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Lists

Text Random Using a List

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Using Length of List


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Lists

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Toggling through colors using a list.


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Lists

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Lists

Iterating Through a List: For Each

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Iteration

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Computing the Sum of the First Three Numbers


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Iteration

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Web Services, APIsand Mashing Data

This chapter introduces web services, APIs, RSS, and mashups, then stepsthrough the development of an Android app that communicates with theTwitter API.

Web Service: To computer users, the web is a bunch of sites that can be visited with a

browser. Programmers see things differently-- to them the web is also a huge

database of information which can be collected and processed (mashed)to create new and interesting apps.

Consider, for instance, the custom bookstore sites that sell books using

Amazon's database of information along with their facilities for on-linetransactions. Such custom bookstores are possible because Amazon, like many sites,

provides two levels of access to information: a human interface and anapplication programmer interface (API)

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Mashups: The term mashup perhaps originated in the music field, with Eminem's

album The Slim Shady LP combining samples from various other songs and artists.

Today, numerous sites like ccmixter help artists mashup samples andcreate new art. Just as music can be remixed, so can web programs and information. To a programmer, a mashup is a program that takes data from multiple

sources (APIs) and combines it in interesting ways.

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most popular example, and one of the first, is housingmaps.com whichcombines data from craigslist.com and Google's maps API.

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RSS(Really Simple Syndication) RSS is a specific XML language that is used by most blogs and in general

any service that just needs to send out a simple list of items in an XMLformat.

An App Inventor Twitter Client for Android

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Persistent Data

Most interesting apps keep track of data over time, usually in some type of database. App Inventor provides two components, TinyDB and TinyWebDB , which allow your app to put things in a database and retrievethem later.

Persistent data is information stored in a database or a file. It is persistentin that even when the user closes the app, the data lives on.

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Persistent Data

TinyWebDB: App Inventor provides a component, tinywebdb, which allows for apps to

store and retrieve data from a database. The component can store data on any web service that follows a particular

protocol.

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Persistent Data

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App Inventor Capabilities and Limitations

You can build many apps with App Inventor, but there are limitations. Most of the limitations are due to the immaturity of the tool-- the App

Inventor team hasn't yet implemented the functionality, but will.

Capabilities

Access to most of the phone's functionality: phone calls, SMS texting,sensors for location, orientation, and acceleration, text-to-speech andspeech recognition, sound, video.

The ability to invoke other apps, with the ActivityStarter component Programming control just as with a textual language. There are blocks for

conditionals (if, ifelse), foreach, and while, and a fairly comprehensive listof math and logic blocks.

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App Inventor Capabilities and Limitations

Database access, both on the device and on the web. So you can save datapersistently, and with a web database share data amongst phones.

Access to web information sources (APIs)-- you can bring in data fromFacebook, Amazon, etc. See limitations below.

Limitations: Limited UIs. Limited Access to the device Limited Access to Web Limited access to the Android Market

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References

Image courtesy : Google App Inventor web site.

http://developer.android.com

Wikipedia
http://developer.android.com/http://developer.android.com/

Android Beginner Lecture 3-4

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