Download Write a program in Java with class Rectangle with

Write a program in Java with class Rectangle with the data fields width, length, area and colour.
The length, width and area are of double type and colour is of string type. The methods are
get_length(), get_width(), get_colour() and find_area(). Create two objects of Rectangle and
compare their area and colour. If the area and colour both are the same for the objects then
display “ Matching Rectangles”, otherwise display “ Non-matching Rectangle”.
ASSIGNMENT NO 7
Title: Demonstrate use of class and methods.
Objectives: To learn concept of classes, methods, objects and use of built in functions in Java.
Problem Statement: Write a program in Java with class Rectangle with the data fields width,
length, area and colour. The length, width and area are of double type and colour is of string
type. The methods are get_length(), get_width(), get_colour() and find_area(). Create two objects
of Rectangle and compare their area and colour. If the area and colour both are the same for the
objects then display “ Matching Rectangles”, otherwise display “ Non-matching Rectangle”.
Outcomes: Students will be able to demonstrate use of variables, data types, operators and
expressions and switch statement in Java.
Hardware requirements: Any CPU with Pentium Processor or similar, 256 MB RAM or more,
1 GB Hard Disk or more.
Software requirements: 64 bit Linux/Windows Operating System, JDK 1.4 or later
Theory:
Object in Java : An entity that has state and behavior is known as an object e.g. chair, bike,
marker, pen, table, car etc. It can be physical or logical (tangible and intangible). The example of
intangible object is banking system. An object has three characteristics:
1. state: represents data (value) of an object.
2. behavior: represents the behavior (functionality) of an object such as deposit, withdraw
etc.
3. identity: Object identity is typically implemented via a unique ID. The value of the ID is
not visible to the external user. But, it is used internally by the JVM to identify each
object uniquely.
For Example: Pen is an object. Its name is Reynolds, color is white etc. known as its state. It is
used to write, so writing is its behavior.
Object is an instance of a class. Class is a template or blueprint from which objects are created.
So object is the instance(result) of a class.
Object Definitions:
 Object is a real world entity.
 Object is a run time entity.
 Object is an entity which has state and behavior.

Object is an instance of a class.
Class in Java : A class is a group of objects which have common properties. It is a template or
blueprint from which objects are created. It is a logical entity. It can't be physical.
A class in Java can contain:
1. fields
2. methods
3. constructors
4. blocks
5. nested class and interface
Syntax to declare a class:
class <class_name>{
field;
method;
}
Instance variable in Java: A variable which is created inside the class but outside the method,
is known as instance variable. Instance variable doesn't get memory at compile time. It gets
memory at run time when object(instance) is created. That is why, it is known as instance
variable.
Method in Java : A Java method is a collection of statements that are grouped together to
perform an operation. When you call the System.out.println() method, for example, the system
actually executes several statements in order to display a message on the console.
Now you will learn how to create your own methods with or without return values, invoke a
method with or without parameters, and apply method abstraction in the program design.
Creating Method : Considering the following example to explain the syntax of a method −
Syntax
public static int methodName(int a, int b) {
// body
}
Here,
public static − modifier
int − return type
methodName − name of the method
a, b − formal parameters
int a, int b − list of parameters
Method definition consists of a method header and a method body. The same is shown in the
following syntax −
Syntax
modifier returnType nameOfMethod (Parameter List) {
// method body
}
The syntax shown above includes −
1. modifier − It defines the access type of the method and it is optional to use.
2. returnType − Method may return a value.
3. nameOfMethod − This is the method name. The method signature consists of the method
name and the parameter list.
4. Parameter List − The list of parameters, it is the type, order, and number of parameters of
a method. These are optional, method may contain zero parameters.
5. method body − The method body defines what the method does with the statements.
Example
Here is the source code of the above defined method called max(). This method takes two
parameters num1 and num2 and returns the maximum between the two −
/** the snippet returns the minimum between two numbers */
public static int minFunction(int n1, int n2) {
int min;
if (n1 > n2)
min = n2;
else
min = n1;
return min;
}
Method Calling : For using a method, it should be called. There are two ways in which a method is
called i.e., method returns a value or returning nothing (no return value).
The process of method calling is simple. When a program invokes a method, the program control
gets transferred to the called method. This called method then returns control to the caller in two
conditions, when −
1. the return statement is executed.
2. it reaches the method ending closing brace.
The methods returning void is considered as call to a statement. Lets consider an example −
System.out.println("UNDERDSTAND!!! IMPLEMENT!!! ANALYZE!!!");
The method returning value can be understood by the following example −
int result = sum(6, 9);
Following is the example to demonstrate how to define a method and how to call it −
Example
public class ExampleMinNumber {
public static void main(String[] args) {
int a = 11;
int b = 6;
int c = minFunction(a, b);
System.out.println("Minimum Value = " + c);
}
/** returns the minimum of two numbers */
public static int minFunction(int n1, int n2) {
int min;
if (n1 > n2)
min = n2;
else
min = n1;
return min;
}
}
This will produce the following result −
Output
Minimum value = 6
new keyword in Java : The new keyword is used to allocate memory at run time. All objects get
memory in Heap memory area.
Conclusion : In this assignment, we have studied classes and methods in Java and demonstrated
their use in program.
Roll
No.
Name
Student
of Date
of Date
of Grade
Performance Assessment
Program
class Rectangle
{
double len,br; //variable for length, breadth and color
String color;
double area;
void read() //function to enter values from keyboard/user
{
System.out.println("Enter Length and Width of Rectangle");
len=Double.parseDouble(System.console().readLine());
br=Double.parseDouble(System.console().readLine());
System.out.println("Enter Color of Rectangle");
color=System.console().readLine();
}
Sign
of Sign
of
Student
Faculty
void display()
{
System.out.println("Length and Width of Rectangle : "+len+","+br);
System.out.println("Color of Rectangle"+color);
System.out.println("Area of Rectangle is"+area);
}
double findArea()
{
area= len*br;
return area;
}
String getColor()
{
return color;
}
public static void main(String args[])
{
Rectangle r1,r2;
r1=new Rectangle();
r2=new Rectangle();
System.out.println("********First Rectangle************");
r1.read();
System.out.println("************Second Rectangle************");
r2.read();
System.out.println("********First Rectangle************");
r1.display();
System.out.println("************Second Rectangle************");
r2.display();
double a1=r1.findArea();
double a2=r2.findArea();
String c1=r1.getColor();
String c2=r2.getColor();
if((a1==a2) && (c1.equalsIgnoreCase(c2)))
System.out.println("Rectangles are matching");
else
System.out.println("Rectangles are not matching");
}
}
OUTPUT: