Implementation of a Basic Calculator with

Scientific Functions in Android

Hibban Buhari

CST/12/COM/00325

Faculty of Computer Science and Information Technology

Department of Computer Science

Bayero University Kano.

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Certification

This is to certify that the work in the project entitled Implementation of a

Basic Calculator with Scientific Functions in Android Mobile Devices by

Hibban Buhari is a SIWES Mini Project work carried out under my

supervision and guidance in partial fulfillment of the requirements for the

award of the degree of Bachelor of Computer Science.

S. H. Muhammad

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Acknowledgment

I would like to use this opportunity to express my humble gratitude to Mal.

S. H. Muhammad under whom I executed this project. His constant

guidance and willingness to share his vast knowledge made me understand

this project and its manifestations in great depths and helped me to

complete the assigned tasks.

I would like to thank all Faculty members and sta of the Department of

Computer Science, B.U.K for their generous help in various ways for the

completion of this work.

Finally, yet importantly, I would like to express my heartfelt thanks to my

beloved parents for their blessings, my friends and classmates for their help

and wishes for the successful completion of this project.

Hibban Buhari

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Abstract

Since ages, calculation has been one of the most important way to enable

human beings compute values in various distinct being it marketing,

accounting, e.t.c. Calculator plays vital role in the history of mankind

originating from the Abacus, to the invention of the first electronic

calculator by Blaise Pascal. This helps individuals and organization in

computing various number together.

In this project, an attempt has been made to design in implement a

scientific-like calculator for mobile devices. The aim of the project is to

create an Android mobile application for use in carrying out mathematical

computations that can be used by all. This application receives input from

the user and performs the required arithmetic operation.

This application uses Android application development toolkit. Android is

a Linux-based operating system developed for smartphones or tablet

computers. It is a stack of software that includes operating system,

middleware and libraries and APIs written in C. The Android application

is developed in Java-like language using the Android Software

Development Kit (SDK). The Integrated Development Environment (IDE)

which is ocially supported for Android apps development and used in

this project is Android Studio, it requires no plugin as it is the new

repository to Android Developers to use, better than Eclipse, which uses

the Android Development Tools (ADT) plugin.

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Table of Contents Certification ............................................................................................ ii

Acknowledgment ................................................................................... iii

Abstract .................................................................................................. iv

Chapter 1 ................................................................................................. 1

Introduction ............................................................................................. 1

1.1 What is Android? ............................................................................ 1

1.2 The Android Platform ..................................................................... 2

1.3 Android Software Stack. ................................................................. 2

1.3.1 Application Framework ............................................................ 3

1.3.2 Dalvik Virtual Machine (DVM) ............................................... 3

1.3.3 SQlite ....................................................................................... 4

1.3.4 Linux Kernal ............................................................................ 4

1.3.5 System Libraries and Android Runtime System ....................... 5

1.3.6 Application Framework Layer .................................................. 6

1.3.7 Applications & Widgets Layer ................................................. 6

1.4 Objective ........................................................................................ 7

Chapter 2 ................................................................................................. 8

General Description, Requirement Analysis and Specification ................ 8

2.1 Introduction .................................................................................... 8

2.2 Product Perspective ........................................................................ 8

2.3 General Constraints ........................................................................ 8

2.4 Requirement Analysis ..................................................................... 9

2.5 Functional Requirements of the System .......................................... 9

Chapter 3 ............................................................................................... 11

Design & Implementation ...................................................................... 11

3.1 Function Oriented Software Design .............................................. 11

3.2 Object Oriented Software Design ................................................. 11

3.3 Implementation ............................................................................. 12

3.4 Android API ................................................................................. 12

3.5 Graphical User Interface ............................................................... 13

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Chapter 4 ............................................................................................... 15

Conclusions and Future Work ................................................................ 15

4.1 Conclusion .................................................................................... 15

4.2 Future Work ................................................................................. 15

References ............................................................................................. 16

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Chapter 1

Introduction

Since ages, calculation has been one of the most important way to enable

human beings compute values in various distinct being it marketing,

accounting, e.t.c. Calculator plays vital role in the history of mankind

originating from the Abacus, to the invention of the first electronic

calculator by Blaise Pascal. This helps individuals and organization in

computing various number together.

The design in implements a scientific-like calculator for mobile devices.

The aim of the project is to create an Android mobile application for use in

carrying out mathematical computations that can be used by all. This

application receives input from the user and performs the required

arithmetic operation.

1.1 What is Android?

Android is a Linux-based operating system developed for smart phones or

tablet computers. It is a stack of software that includes operating system,

middleware and libraries and APIs written in C. It was developed by

Google and Open Handset Alliance in July, 2005. Android is an open

source and Google releases the source code under Apache license. This

open source and free license allow the manufacturers and the enthusiastic

developers to freely develop and modify their applications in Java-like

language that utilizes Google-developed Java libraries.

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The Android applications are developed using the Android software

development kit (SDK). The SDK includes a comprehensive set of

development tools which includes a debugger, software libraries, a handset

based emulator which is based on QEMU (Quick EMUlator) and tutorials.

The integrated development environment (IDE) which is ocially

supported for Android apps development is Eclipse which uses the

Android Development Tools (ADT) plugin. The following are the several

features which help in the development of Android applications:

1.2 The Android Platform

The Android Platform is a software stack designed primarily but not

exclusively to support mobile devices such as phones and tables.

The stack has several layers. The layers ranges from low level operating

system services that manages the device and its configurations up to

sample Applications like Phone Dialer, Contacts Database and Web

Browser. Android software also comes with a Software Developers Kit,

SDK, used to create Android Applications.

1.3 Android Software Stack.

The Android software stack is organized into several layers as follows:

1. Linux Kernel Layer;

2. System Libraries and Android Runtime System;

3. Application Framework Layer; and

4. Standard Applications Layer.

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1.3.1 Application Framework

Android application framework is supported by number of open source

libraries like OpenSSL, SQLite, and Libc. The application framework is

also supported by the Android core libraries. The framework is based on

UNIX file system permissions which ensures security as the applications

can have only those abilities that mobile phone owner give at the time of

installation. The application framework enables the reuse and replacement

of components.

1.3.2 Dalvik Virtual Machine (DVM)

Dalvik is a process virtual machine used in Googles Android operating

system. It is a low memory based virtual machine which is especially

designed for Android to run on the embedded systems and work eciently

in low power. The programs are commonly written in Java and are

compiled into bytecode. This bytecode is then converted form JVM .class

files to .dex file (Dalvik executable) before installation on a device.

Fig1.1: Dalvik VM Conversion

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1.3.3 SQlite

Android OS contains the SQLite database management classes which is

used by an application to maintain its own private database. SQLite is a

relational database management system contained in C programming

library. It is mostly preferred as embedded database for local or client

storage in application software. It has many bindings to the programming

languages.

1.3.4 Linux Kernal

The Linux Kernel Layer is the lowest layer of software in the Android

Platform. It provides core services that Android computing devices rely on

and generic operating system services.

These services include:

a. permission architecture to restrict access to data and resources to

processes that have proper authorization;

b. memory and process management to enable multiple processes run

simultaneously without interfering with each other; and

c. device drivers to enable Android communicate with the wide range

low-level hardware components that can couple with computing

devices such as memory, camera.

Android Linux Kernel also has some specific components. These are but

not limited to:

a. Android Linux Kernel includes built in power management to enable

mobile device run on battery power;

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b. it also has built-in memory sharing and memory management

features because of the limited memory of mobile devices;

c. it also includes inter-process communication mechanism called

binder to allows multiple processes and services share resources in

sophisticated ways.

1.3.5 System Libraries and Android Runtime System

The system libraries often referred to as the native library are written in C

and C++. They handle a lot of core performance sensitive activities on

Android devices.

The Android libraries has built-in system C library handling process and

thread creation, mathematical computation, and memory allocation, also,

the System Libraries include:

i. the Surface Manager for managing and updating the display;

ii. the Media Framework used for playing back Audio and Video files;

iii. the WebKit for rendering Browser and opening WebPages;

iv. Open GL for high performance graphics; and

v. SQLite for managing in-memory relational database engine.

In addition to the System Libraries, the layer also includes the Android

Runtime which supports writing and running Android applications.

The Android Runtime System has two main components i.e. the Core Java

Libraries and the Dalvik Virtual Machine.

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1.3.6 Application Framework Layer

The Application Framework Layer contains reusable softwares that many

Mobile Applications may likely need e.g. the View System (contains text,

buttons, e.t.c.).

These include:

Package Manager;

Window Manager;

View System;

Resource Manager;

Activity Manager;

Location Manager;

Notification Manager.

1.3.7 Applications & Widgets Layer

Android OS come with some built in Applications in the Mobile Devices.

The Applications & Widgets Layer is the highest layer in the architectural

diagram of Android layers. The layer handles the built in Applications

which include the standard applications that can take over the whole screen

and interact with the user comprising the Home Screen, the Contacts

Database, the Phone Dialer, the Web Browser, Email Reader, e.t.c. End

users will only see these programs.

On the other hand, Widgets (sometimes called gadgets) only operate in a

small rectangle of the Home Screen application. One advantage of the

Android Application & Widgets Layer is that these standard Applications

are not hard-coded in the device. A developer may substitute an

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Application with his own 3rd party Application that he feels is a better

Application.

Figure 1.2: Growth Chart for the android OS

Nowadays, Android phones have emerged as the worlds most popular

mobile platform. Its the largest installed base of any mobile platform and

growing fast. Millions of users are using android phones and android

applications are becoming more and more popular.

1.4 Objective

Design a Calculator to use to perform basic arithmetic computations for

mobile devices for easy and proper evaluation of computation.

1. Develop and implement a Calculator.

2. To create an Android mobile application that provides a User

Interface to interact with the system.

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Chapter 2

General Description, Requirement Analysis and Specification

2.1 Introduction

The calculator system gives an ease in the working and performing

mathematical functions of the system in an easy way through an intuitive

interface that makes it easy for user to tap on using the rich gesture facility

of Android Operating System

2.2 Product Perspective

The Calculator System simplifies computations of our day-to-day activities

using our mobile devices. The system can be deployed on every mobile

device running the Android OS. The software focus on the easy way of

conducting mathematical computations with the use of mobile phones.

2.3 General Constraints

The general constraints of this system are of two types

1. Hardware Constraints

2. Software constraints

Any devices which can run Android Operating System. And the following

are the software constraints of the system.

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2.4 Requirement Analysis

The Application developed follows the following steps of Software

Development Lifecycle. The System Requirement Specification model

developed for the system is as listed below

The SRS model Contains

Functional Requirements.

Non-Functional requirements

2.5 Functional Requirements of the System

The functional requirements part discuss the functional behavior that should

be possessed by the system. Each requirement maps to a high level function

that transforms the given set of input data into output data.

Dierent functional requirements possessed by the system are:-

Activity_main.xml

Description: The xml file containing the user interface of the system.

Users would be presented with an interface to interact with through

their mobile phones.

FirstActivity.java

Description: The file containing the Java declaration and expression

files. The MainActivity.java is a class that extends the Activity class

and implements various methods contained in the Activity class.

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Splash.xml

Description: The xml file containing the Splash Screen user interface

of the system. This activity runs for 5 seconds providing the user with

the devices date and time and calls the First Activity.

Splash.java

Description: The file containing the Java declaration and expressions

for the Splash.xml. The Splash.java is a class that extends the Activity

class inherits the FirstActivity and implements various methods

contained in the Activity class.

It also uses an Intent method used in the Activity class in Android to

request functionality from other Android components.

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Chapter 3

Design & Implementation

The design phase emphasizes on the transformation of user requirements as

defined in the SRS document, into a form that is suitable for coding.

The design phase can be broadly classified in two levels.

Preliminary or high level design

Detailed design

The preliminary design can be further divided into two sub categories

Function Oriented Software Design

Object Oriented Software Design

3.1 Function Oriented Software Design

This design model can be represented by drawing the DFDs (Data Flow

Diagrams) for the given SRS document.

A data flow diagram is a graphical representation of the data flow through an

information system which is used to model the process aspects of the system.

DFD is the preliminary step used to create an overview of the system. DFD is

used for structured design.

3.2 Object Oriented Software Design

In this design approach the system is viewed as a collection of entities

(objects). Each object manages its own properties (attributes) and state.

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3.3 Implementation

The Application is implemented according to three tier architecture. Three tier

architecture is commonly known as Client-Server architecture, where Client

is the consumer of the services, also the requester of services whereas the

server side is the provider of services. The third layer that is the middle layer

that converts the users requests into server understandable form.

The system developed contains Android application in its front end ie the

client side. The middle layer that connects the client side to the server side is

the Jason (JavaScript Object Notation) Parser that is primarily used to transmit

data between server and server application.

3.4 Android API

API stand for Application Programming Interface. It contains the following

features-

Applications are written in Java;

The source code file is compiled into Java Bytecode file;

DX converts the Java Bytecode file to single Dex Bytecode file;

The Dex file is then packaged with other Application resources and

installed on the Device;

And finally, when the user launches the Application, the Dalvik Virtual

Machine executes the Dex file.

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3.5 Graphical User Interface

The application GUI is developed using the android SDK and the various

forms are as shown below.

Fig. 3.3: Startup Splash Screen

Fig. 3.1: Android API Debug process

Fig. 3.2: Launcher Icon

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Fig 3.4: Main Activity

Fig 3.5: Result from

Evaluation

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Chapter 4

Conclusion and Future Work

4.1 Conclusion

The Calculator for mobile devices is a very effective tool which can be used

to a great extent. The system is portable and can be easily installed and used

on any mobile phones supporting Android OS.

The use of this system can result in a reduction of number of time spent

computing values. It also provides an interface which is easy to understand by

the users and greatly helps in adapting to the use of this system.

4.2 Future Work

The system can be further enhanced and several other functionalities can be

added. The system can be made to send result to an output file, generate log

and usage statistics, and can be made to retrieve the generated log activity.

The present system prints to the stack usage logs and statistics.

The system can also be enhanced by using voice recognition feature of the

Android.

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References

Android Developers. (2014, December 6). Creating an Android Project. Retrieved from Android Developers Training: https://developer.android.com/training/basics/firstapp/creating-project.html

Lars Vogel. (2014, December 28). Vogella. Retrieved from Android Development: http://www.vogella.com

Murphy, M. L. (2009 - 2011). Android Programming Tutorials. United State of America: CommonsWare.

Travis. (n.d.). Android Application Development Tutorial. Retrieved from http://www.travis.com