Section1 compound data class

Compound Data: Class

Compound Data - Class 1

Topic

• How to Design Program– What is program and design program?

– Basic steps of a program design

• The Varieties of Data

• Compound Data: Class

• Design Class

• Design method


How To Design program


What is Program?

• A computer program is a set of ordered instructions for a computer to perform a specific task or to exhibit desired behaviors.

• Without programs, computers are useless.

• A software application or software program is the most commonly found software on the computer. – Microsoft Word is a word processor program that allows

users to create and write documents.


What is Programming?

• Computer programming is the process of designing, writing, testing, debugging, and maintaining the source code of computer programs.

• Programming language :– The source code of program is written as a series of

human understandable computer instructions in a that can be read by a compiler , and translated into machine code so that a computer can understand and run it.

– There are many programming languages such as C++, C#, Java, Python, Smalltalk, etc.


Design Program

• The process of programming often requires expertise in many different subjects, including knowledge of the application domain, specialized algorithms and formal logic.

• Main goal of the design process is to lead from problem statements to well-organized solutions

• Design guidelines are formulated as a number of program design recipes.– A design recipe guides a beginning programmer

through the entire problem-solving process


How to Design Program

To design a program properly, a programmer must:

1. analyze a problem statement, typically stated as a word problem;

2. express its essence, abstractly and with examples;

3. formulate statements and comments in a precise language;

4. evaluate and revise these activities in light of checks and tests; and

5. pay attention to details.


Basic steps of a program design recipe

1. Problem Analysis & Data Definition– the description of the class of problem data

2. Contract, Purpose & Effect Statements, Header– the informal specification of a program's behavior

3. Examples– the illustration of the behavior with examples

4. method Template– the development of a program template or layout

5. method Definition– the transformation of the template into a complete definition; and

6. Tests– the discovery of errors through testing.


Why Java?

• Object-oriented programming languages

• Open source

• A cross platform language – Portability: "Write Once, Run Anywhere"

• Spread Rapidly through WWW and Internet

• JVM (Java Virtual Machine)

• JRE (Java Runtime Environment)

• JDK (Java Deverloper Kit)


IDE

• IDE: Integrated Development Environment– Netbean : supported by Sun– Eclipse : open source, supported by IBM


The Varieties of Data


12

Primitive Forms of Data

• Java provides a number of built-in atomic forms of data with which we represent primitive forms of information.


Integer type

Name Size Range Default value

byte 1 byte -128…127 0

short 2 bytes -32,768…32,767 0

int 4 bytes -2,147,483,648 to2,147,483,648

0

long 8 bytes -9,223,372,036,854,775,808 to9,223,372,036,854,775,808

0L


14

Decimal type

Name Size Range Default value

float 4 bytes ±1.4 x 10-45 �±3.4 x 1038 0.0f

double 8 bytes ±4.9 x 10-324 �±1.8 x 10308 0.0d


15

Character type

Java represent a Unicode character (2 bytes)

• Q: Distinguish char type and String type ?• A:

– char c = 't';– String s = "tin hoc";

Name Size Range Default valuechar 2 bytes \u0000 … \uFFFF \u0000


16

Boolean type

Name Size Range Default valueboolean 1 byte false, true false


String

• Strings to represent symbolic. Symbolic information means the names of people, street addresses, pieces of conversations, …

• a String is a sequence of keyboard characters enclosed in quotation marks– "bob"– "#$%ˆ&"– "Hello World"– "How are U?"– "It is 2 good to B true."


Compound Data: Classes

• For many programming problems, we need more than atomic forms of data to represent the relevant information.

• Consider the following problem:


Coffee example

• Develop a program that computes the cost of selling bulk coffee at a specialty coffee seller from a receipt that includes the kind of coffee, the unit price, and the total amount (weight) sold

• Examples1) 100 pounds of Hawaiian Kona at $15.95/pound

→ $1,595.002) 1,000 pounds of Ethiopian coffee at $8.00/pound

→ $8,000.003) 1,700 pounds of Colombian Supreme at $9.50/pound

→ 16,150.00


Class Diagram: abstractly express

Property or fieldData type

Class Name

CoffeeReceipt

- String kind- double pricePerPound- double weight

Method


Define Java Class, Constructor

class CoffeeReceipt {

String kind;

double pricePerPound;

double weight;

CoffeeReceipt(String kind,

double pricePerPound, double weight) {

this.kind = kind;

this.pricePerPound = pricePerPound;

this.weight = weight;

}

}

class definition

CONSTRUCTOR of the class

Field declarations. Each declaration specifies the type of values that the field name represents. Accordingly, kindstands for a String and pricePerPoundand weight are doubles


About Constructor

• Constructor name is same class name.

• The parameters of a constructor enclose in () quotes, separated by commas (,).

• Its body is a semicolon-separated (;) series of statement this.fieldname = parametername;

CoffeeReceipt(String kind, double pricePerPound,

double weight) {

this.kind = kind;

this.price = price;


}


Translate sample

• It is best to translate some sample pieces of information into the chosen representation.

• This tests whether the defined class is adequate for representing some typical problem information.

• Apply the constructor to create an object (instance)of the CoffeeReceipt class:– new CoffeeReceipt("Hawaiian Kona", 15.95, 100)– new CoffeeReceipt("Ethiopian", 8.00, 1000)– new CoffeeReceipt("Colombia Supreme", 9.50, 1700)


Test Class

import junit.framework.*;

public class CoffeeReceiptTest extends TestCase {

public void testConstructor() {

new CoffeeReceipt("Hawaiian Kona", 15.95, 100);

new CoffeeReceipt("Ethiopian", 8.0, 1000);

new CoffeeReceipt("Colombian Supreme ", 9.5, 1700);

}

}

Import test unit library

Define class CoffeeReceiptTestis test case.

Test method that name is testXXX

This tests contain statement to create an object of the CoffeeReceipt class, you apply the constructor to as many values as there are parameters:new CoffeeReceipt("Hawaiian Kona", 15.95, 100)


Date example

• Develop a program that helps you keep track of daily. One date is described with three pieces of information: a day , a month , and a year

• Class diagram


Date- int day- int month- int year

Define Class, Constructor and Test

import junit.framework.*;public class DateTest extends TestCase {

public void testConstrutor() {new Date(5, 6, 2003); // denotes June 5, 2003new Date(6, 6, 2003); // denotes June 6, 2003new Date(23, 6, 2000); // denotes June 23, 2000

}}

class Date { int day;int month;int year; Date(int day, int month, int year) {

this.day = day;this.month = month;this.year = year;

}}


GPS Location example

• Develop a GPS navigation program for cars. The physical GPS unit feeds the program with the current location. Each such location consists of two pieces of information: the latitude and the longitude.

• Class diagram


GPSLocation- double latitude- double longitude

Define Class, Constructor and test

class GPSLocation {

double latitude /* degrees */;

double longitude /* degrees */;

GPSLocation(double latitude, double longitude) {

this.latitude = latitude;

this.longitude = longitude;

}

}


public class GPSLocationTest extends TestCase {

public void testConstrutor() {

new GPSLocation (33.5, 86.8);



}

}


Three steps in designing Classes

1. Read the problem statement. Look for statements that mention or list the attributes of the objects in your problem space. Write down your findings as a class diagram because they provide a quick overview of classes.

2. Translate the class diagram into a class definition, adding a purpose statement to each class.

3. Obtain examples of information and represent them with instances of the class. Conversely, make up instances of the class and interpret them as information.


Excercice 1.1

• Develop a program that assists bookstore employees. For each book, the program should track the book’s title , its price , its year of publication, and the author’s name …

• Develop an appropriate class diagram (by hand) and implement it with a class. Create instances of the class to represent these three books:1. Daniel Defoe, Robinson Crusoe, $15.50, 1719;2. Joseph Conrad, Heart of Darkness, $12.80, 1902;3. Pat Conroy, Beach Music, $9.50, 1996.


Exercise 1.2

• Add a constructor to the following partial class definition and draw the class diagram // represent computer imagesclass Image {

int height; // pixelsint width; // pixelsString source; // file nameString quality; // informal

}

• Explain what the expressions mean in the problem context and write test class:new Image(5, 10, "small.gif", "low")new Image(120, 200, "med.gif", "low")new Image(1200, 1000, "large.gif", "high")


Exercise 1.3

• Translate the class diagram in figure into a class definition. Also create instances of the class

Compound Data - Class

Automobile- String model- int price [in dollars]- double mileage [in miles per gallon]- boolean used

32

Exercises 1.4

• Write Java class, constructor and test constructor for representing points in time since midnight. A point in time consists of three numbers: hours, minutes, and seconds.


Class Method


Expressions

• For the primitive types int, double, and boolean, Java supports a notation for expressions that appeals to the one that we use in arithmetic and algebra courses.

• For example, we can write10 ∗ 12.50

width + height

Math.PI ∗ radius


Arthimetic and Relation Operators

Symbol Parameter types Result Example

+ numeric, numeric numeric x + 2 addition

- numeric, numeric numeric x – 2 subtraction

* numeric, numeric numeric x * 2 multiplication

/ numeric, numeric numeric x / 2 division

> numeric numeric x > 2 greater than

>= numeric, numeric numeric x >= 2 greater or equal

< numeric, numeric numeric x < 2 less than

<= numeric, numeric numeric x < 2 less or equal

== numeric, numeric numeric x == 2 equal

!= numeric, numeric numeric x != 2 not equal


Logic Operators

Symbol Parameter types Result Example

! boolean boolean !(x < 0) logical negation

&& boolean, boolean boolean a && b logical and

|| boolean, boolean boolean a || b logical or

• Example(x != 0) && (x < 10) . . . determines whether a is not equal to x (int or double) and x is less than 10


Method Calls

• A method is roughly like a function. Like a function, a method consumes data and produces data.

• However, a METHOD is associated with a class.

• Example:– To compute the length of the string in Java, we use the

length method from the String class like this:"hello world".length()

– String str = "hello";

str.concat("world")

concatenate "world" to the end of the argument "hello"– Math.sqrt(10) is square of 10


Method Calls

• When the method is called, it always receives at least one argument: an instance of the class with which the method is associated; – Because of that, a Java programmer does not speak of

calling functions for some arguments, but instead speaks of INVOKING a method on an instance or object

• In general, a method call has this shape:object.methodName(arg1, arg2, ...)


Methods for Classes

• Take a look at this revised version of our first problem. . . Design a method that computes the cost of selling bulk coffee at a specialty coffee seller from a receipt that includes the kind of coffee, the unit price, and the total amount (weight) sold. . .


Method example

• Methods are a part of a class.

• Thus, if the CoffeeReceipt class already had a cost method, we could write:new CoffeeReceipt("Kona", 15.95, 100).cost()

and expect this method call to produce 1595.0.


CoffeeReceipt


??? cost(???)

41

Designs through Templates

• First we add a contract, a purpose statement, and a header for cost to the CoffeeReceipt class


// the bill for a CoffeeReceipt sale


String kind;

double pricePerPound; // in dollars per pound

double weight; // in pounds


double weight) { ... }

// to compute the total cost of this coffee purchase

// [in dollars]

double cost() { ... }

}

Contract is a METHOD SIGNATURE

a purpose statement

42

Primary argument: this

• cost method is always invoked on some specific instance of CoffeeReceipt . – The instance is the primary argument to the method, and it

has a standard name, this

• We can thus use this to refer to the instance of CoffeeReceipt and access to three pieces of data: the kind, the pricePerPound, and the weight in method body– Access field with: object.field– E.g: this.kind, this.pricePerPound, this.weight


cost method template and result



// [in cents]

double cost() {

return this.pricePerPound * this.weight;

}

• the two relevant pieces are this.price and this.weight. If we multiply them, we get the result that we want:


// [in cents]

double cost() {

...this.kind...

...this.pricePerPound...

...this.weight...

}

44

CoffeeReceipt class and method



String kind;

double pricePerPound;

double weight;


double weight) {

this.kind = kind;

this.pricePerPound = pricePerPound;


}


// [in dollars]

double cost() {

return this.pricePerPound * this.weight;

}

}

45

Test cost method


import junit.framework.TestCase;


public void testContructor() {

...

}

public void testCost() {

assertEquals(new CoffeeReceipt("Hawaiian Kona",

15.95, 100).cost(), 1595.0);

CoffeeReceipt c2 =


assertEquals(c2.cost(), 8000.0);

CoffeeReceipt c3 =


assertEquals(c3.cost(), 16150.0);

}

}

46

Methods consume more data

Design method to such problems:

… The coffee shop owner may wish to find out whether a coffee sale involved a price over a certain amount …


CoffeeReceipt


double cost()??? priceOver(???)

Purpose statement and signature

• This method must consume two arguments:– given instance of coffee: this

– a second argument, the number of dollars with which it is to compare the price of the sale’s record.


inside of Coffee// to determine whether this coffee’s price is more

// than amount

boolean priceOver(double amount) { ... }

Examples

• new CoffeeReceipt("Hawaiian Kona", 15.95,

100).priceOver(12) expected true

• new CoffeeReceipt("Colombian Supreme", 9.50,

1700).priceOver(12) expected false


priceOver method template and result


// to determine whether this coffee’s price

// is more than amount

boolean priceOver(int amount) {

return this.pricePerPound > amount;

}

The only relevant pieces of data in the template are amt and this .price:

// to determine whether this coffee’s price

// is more than amount

boolean priceOver(int amount) {

... this.kind

... this.pricePerPound

... this.weight

... amount

}

50

Test priceOver method


import junit.framework.TestCase;


...

public void testPriceOver() {

CoffeeReceipt c1 =

new CoffeeReceipt("Hawaiian Kona", 15.95, 100);

CoffeeReceipt c2 =


CoffeeReceipt c3 =


assertTrue(c1.priceOver(12));

assertFalse(c2.priceOver(12));

assertFalse(c3.priceOver(12));

}

}

51

Posn example

• Suppose we wish to represent the pixels (colored dots) on our computer monitors. – A pixel is very much like a Cartesian point. It has an x

coordinate, which tells us where the pixel is in the horizontal direction, and it has a y coordinate, which tells us where the pixel is located in the downwards vertical direction.

– Given the two numbers, we can locate a pixel on the monitor

• Computes how far some pixel is from the origin

• Computes the distance between 2 pixels


Class diagram


Posn- int x- int y

+ ??? distanceTo0(???)+ ??? distanceTo(???)

53

Define Class, Constructor, and Test


class Posn {

int x;

int y;

Posn(int x, int y) {

this.x = x;

this.y = y;

}

}


public class PosnTest extends TestCase {

public void testConstrutor() {

new Posn(5, 12);

Posn aPosn1 = new Posn(6, 8);


}

}

54

Computes

How far some pixel is from the origin

• Examples– Distance from A(5, 12) to O is 13– Distance from B(6, 8) to O is 10– Distance from A(3, 4) to O is 5

Posn- int x- int y

+ ??? distanceToO(???)+ ??? distanceTo(???)


distanceToO method template

class Posn {

int x;

int y;


this.x = x;

this.y = y;}

// Computes how far this pixel is from the origin

double distanceToO() {

...this.x...

...this.y...

}

}


Add a contract, a purpose statement

METHOD SIGNATURE

56

distanceToO method implementation

class Posn {

int x;

int y;


this.x = x;

this.y = y;

}

double distanceToO() {

return Math.sqrt(this.x * this.x + this.y * this.y);

}

}


Test distanceToO method




public void testConstrutor(){

new Posn(5, 12);

Posn aPosn1= new Posn(6, 8);


}

public void testDistanceToO(){

assertEquals(new Posn(5, 12).distanceToO(), 13.0, 0.001);


assertEquals(aPosn1.distanceToO(), 10.0, 0.001);


assertEquals(aPosn2.distanceToO(), 5.0, 0.001);

}

}

58

Computes the distance between 2 pixels

• Example– Distance from A(6, 8) to B(3, 4) is 5


Posn- int x- int y

+ double distanceToO()+ ??? distanceTo(???)

59

distanceTo method templateclass Posn {

int x;

int y;

...


double distanceTo0(){


}

// Computes distance from this posn to another posn

double distanceTo(Posn that) {

...this.x...this.y...

...that.x...that.y...

...this.distantoO()...that.distanceToO()...

}

}

Add a contract, a purpose statement

METHOD SIGNATURE


distanceTo method implementclass Posn {

int x;

int y;

...


double distanceTo0(){


}

// Computes distance from this posn to another posn

double distanceTo(Posn that) {

return Math.sqrt((that.x - this.x)*(that.x - this.x)

+ (that.y - this.y)*(that.y - this.y));

}

}


Test distanceTo method



...

public void testDistanceTo(){

assertEquals(new Posn(6, 8).distanceTo(

new Posn(3, 4)), 5.0, 0.001);



assertEquals(aPosn1.distanceTo(aPosn2), 5.0, 0.001);

}

}


Class diagram - Final


Posn- int x- int y

+ double distanceToO()+ double distanceTo(Posn that)

63

Employee example

An employee has his name and the number of hours of work.

• Determines the wage of an employee from the number of hours of work. Suppose 12 dollars per hour.

• Utopia's tax accountants always use programs that compute income taxes even though the tax rate is a solid, never-changing 15%. Determine the tax on the gross pay.

• Also determine netpay of an employee from the number of hours worked base on gross pay and tax .

• Give everyone a raise to $14

• No employee could possibly work more than 100 hours per week. To protect the company against fraud, the methodshould check that the hours doesn’t exceed 100. If it does, the method returns false. Otherwise, it returns true


Class diagram


Employee- String name- int hours

+ ??? wage(???)+ ??? tax(???)+ ??? netpay(???)+ ??? raisedWage(???)+ ??? checkNotExceed100 (???)

65

Define Class and Contructor and Test


public class Employee {

String name;

int hours;

Employee(String name, int hours) {

this.name = name;

this.hours = hours;

}

}


public class EmployeeTest extends TestCase {

public void testContructor() {

new Employee("Nam", 40);

Employee aEmployee1 = new Employee("Mai", 30);

Employee aEmployee2 = new Employee("Minh", 102);

}

}

66

Compute wage

• Examples– Employee Nam works 40 and earns 480 $– Employee Mai works 30 and earns 360 $– Employee Minh works 100 and earns 1200 $



+ ??? wage(???)+ ??? tax(???)+ ??? netpay(???)+ ??? raisedWage(???)+ ??? checkNotExceed100(???)

67

wage method template


String name;

int hours;


this.name = name;

this.hours = hours;

}

// Determines the wage of an employee

// from the number of hours of work

int wage() {

...this.name...

...this.hours...

}

}


wage method body

class Employee {

String name;

int hours;


this.name = name;

this.hours = hours;

}

// Determines the wage of an employee

// from the number of hours of work

int wage() {

return this.hours * 12;

}

}


Test wage method



...

public void testWage() {

assertEquals(new Employee("Nam", 40).wage(), 480);



assertEquals(aEmployee1.wage(), 360);

assertEquals(aEmployee2.wage(), 1200);

}

}


Compute tax


• Examples– Employee Nam gets 480 $ and has to pay 72 $ for tax– Employee Mai gets 360 $ and has to pay 54 $ for tax– Employee Minh gets 1200 $ and has to pay 180 $ for tax



71

tax method templateclass Employee {

String name;

int hours;


this.name = name;

this.hours = hours;

}

int wage() {


}

// Determines the tax of an employee from the wage

double tax() {

...this.name...

...this.hours...

...this.wage()...

}

}


tax method implement

class Employee {

String name;

int hours;


this.name = name;

this.hours = hours;

}

int wage() {


}

// Determines the tax of an employee from the wage

double tax() {

// this.hours * 12 * 0.15;

return this.wage() * 0.15;

}

}


Test tax method



...

public void testTax() {

assertEquals(new Employee("Nam", 40).tax(), 72.0, 0.001);



Assert.assertEquals(aEmployee1.tax(), 54.0, 0.001);

Assert.assertEquals(aEmployee2.tax(), 180.0, 0.001);

}

}


Class diagram


• Examples– With salary 480 $, Nam just receives 408 $ of netpay– With salary 360 $, Mai just receives 306 $ of netpay– With salary 1200 $, Minh just receives 1020 $ of netpay



75


String name;

int hours;


this.name = name;

this.hours = hours;

}

// Determines the netpay of an employee

double netpay() {

...this.name...

...this.hours...

...this.wage()...

...this.tax()...

}

}

netpay method template


netpay method implementclass Employee {

String name;

int hours;


this.name = name;

this.hours = hours;

}

int wage() {


}

double tax() {

return this.wage()) * 0.15;

}

// Determines the netpay of an employee

double netpay() {

return this.wage() - this.tax();

}

}


Test netpay method


public class TestEmployee extends TestCase {

...

public void testNetpay() {

assertEquals(new Employee("Nam",40).netpay(),

408.0, 0.001);

Employee aEmployee1 = new Employee("Mai",30);

Employee aEmployee2 = new Employee("Minh",100);

Assert.assertEquals(aEmployee1.netpay(), 306.0, 0.01);

Assert.assertEquals(aEmployee2.netpay(), 1020.0, 0.01);

}

}


Class diagram


• Examples– With basic salary 480$, after getting bonus, total income of Nam

is 494– With basic salary 360$, after getting bonus, total salary of Mai is

374– With basic salary 1200$, after getting bonus, total salary of Minh

is 1214



79

raisedWage method templatepublic class Employee {

String name;

int hours;


this.name = name;

this.hours = hours;

}

// Raise the wage of employee with 14$

int raisedWage() {

...this.name...

...this.hours...

...this.wage()...

...this.tax()...

...this.netpay()...

}

}


raisedWage method implementclass Employee {

String name;

int hours;

...

int wage() {


}

double tax() {

return this.wage() * 0.15;

}

double netpay() {

return this.wage() - this.tax();

}

// Raise the wage of employee with 14 $

int raisedWage() {

return this.wage() + 14;

}

}


Test raisedWage methodimport junit.framework.*;

public class TestEmployee extends TestCase {

...

public void testraisedWage(){

assertEquals(new Employee("Nam", 40).raisedWage(),

494, 0.001);



assertEquals(aEmployee1.raisedWage(), 374.0, 0.001);

assertEquals(aEmployee2.raisedWage(), 1214.0, 0.001);

}

}


Class diagram


• Examples– It is true that Nam and Mai work 40 and 30 hours per week– It is impossible for Minh to work 100 hours per week



83

checkNotExceed100 method

templatepublic class Employee {

String name;

int hours;


this.name = name;

this.hours = hours;

}

// Determines whether the number of hours of work

// exceeds 100

boolean checkNotExceed100() {

...this.name...this.hours...

...this.wage()...this.tax()...

...this.netpay()...this.raisedWage()

}

}


checkNotExceed100 method

implementpublic class Employee {

String name;

int hours;


this.name = name;

this.hours = hours;

}

...

// Determines whether the number of hours of work

// exceeds 100

boolean checkNotExceed100() {

return this.hours < 100;

}

}


Test checkNotExceed100 method



...

public void testcheckNotExceed100(){

assertTrue(new Employee("Nam", 40).checkNotExceed100());



assertTrue(aEmployee1.checkNotExceed100());

assertFalse(aEmployee2.checkNotExceed100());

}

}


Class diagram - Final



+ int wage()+ double tax()+ double netpay()+ double raisedWage()+ boolean checkNotExceed100()

87

Design Class Method Steps

1. Problem analysis and data definitions – Specify pieces of information the method needs and output

infomation

2. Purpose and contract (method signature)– The purpose statement is just a comment that describes

the method's task in general terms. – The method signature is a specification of inputs and

outputs, or contract as we used to call it.


Design Class Method Steps (Contd)

3. Examples – the creation of examples that illustrate the purpose

statement in a concrete manner

4. Template – lists all parts of data available for the computation inside of

the body of the method

5. Method definition– Implement method

6. Tests– to turn the examples into executable tests


Exercise 1.5

• Develop the method tax, which consumes the gross pay and produces the amount of tax owed. For a gross pay of $240 or less, the tax is 0%; for over $240 and $480 or less, the tax rate is 15%; and for any pay over $480, the tax rate is 28%.

• Also develop netpay. The method determines the net pay of an employee from the number of hours worked. The net pay is the gross pay minus the tax. Assume the hourly pay rate is $12


Relax…

& Do Exercise


Solution exersise 1.5 : taxWithRate()

public double taxWithRate() {

double grossPay = this.wage();

if (grossPay < 240)

return 0.0;

if (grossPay < 480)

return grossPay * 0.15;

return grossPay * 0.28;

}

public void testTaxWithRate() {

assertEquals(new Employee("Nam", 10).taxWithRate(),

0.0, 0.001);


assertEquals(aEmployee1.taxWithRate(), 54.0, 0.001);


assertEquals(aEmployee2.taxWithRate(), 336.0, 0.001);

}


Solution exersise 1.5: netpayWithRate()

Method implementation

public double netpayWithRate() {

return this.wage() - this.taxWithRate();

}

Unit testing

public void testNetpayWithRate() {

assertEquals(new Employee("Nam", 10).netpayWithRate(),

120.0, 0.001);


assertEquals(aEmployee1.netpayWithRate(), 306.0, 0.001);


assertEquals(aEmployee2.netpayWithRate(), 864.0, 0.001);

}


Date post:	16-Apr-2017
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Section1 compound data class

Education