MyShape

//Program for checking if the shape is a rectangle and further a square

class Rectangle
{
	double length;
	double breadth;

	public Rectangle()
	{
		length=1.0;
		breadth=1.0;
	}


	public Rectangle(double myLength, double myBreadth)
	{
		setLength(myLength);
		setBreadth(myBreadth);
	}

		public void setLength(double length)
	{
		try
		{
		    if(length<0.0 || length>20.0)
		    throw new CustomException("Invalid value");
		    this.length = length;
		}

		catch(CustomException e)
		{
		    System.out.println(e.getMessage());
	   	}
    	}

	    	public void setBreadth(double breadth)
	{
	    try
	    {
		    if(breadth<0.0 || breadth>20.0)
		    throw new CustomException("Invalid value");
		    this.breadth = breadth;
		}
		catch(CustomException e)
		{
			System.out.println(e.getMessage());
	    	}
	}

		public double getLength()
	{
		return length;
	}
	public double getBreadth()
	{
		return breadth;
	}

	//Function for calculating Area
	public double area()
	{
		return length*breadth;
	}

	//Function for calculating perimeter
	public double perimeter()
	{
		return 2*(length+breadth);
	}

}

class CustomException extends Exception
{
	CustomException(String s)
	{
		super(s);
	}
}

//Making a child class MyShape of parent class Rectangle

public class MyShape extends Rectangle
{
	double x[];
	double y[];

	public MyShape(double lengtharr[],double breadtharr[] )
	{
		x=new double[4];
		y=new double[4];
		setValues(lengtharr,breadtharr);
	}

		public void setValues(double lengtharr[],double breadtharr[])
	{
		for(int i=0;i<4;++i)
		{
			if(lengtharr[i]<0 || breadtharr[i]<0)
			{
			System.out.println("Invalid value");
			System.exit(1);
		    	}
		}

				//Now checking if the value is greater than 20
		for(int i=0;i<4;++i)
		{
			verifyValues(lengtharr[i]);
			verifyValues(breadtharr[i]);
		}

				for(int i=0;i<4;++i)
		{
			x[i] = lengtharr[i];
			y[i] = breadtharr[i];
		}

	}

		public void Length()
	{
        	if(Math.sqrt((x[0]-x[3])*(x[0]-x[3])+(y[0]-y[3])*(y[0]-y[3]))==0)
      		{
        	System.out.println("Invalid length");
        	System.exit(0);
	  	}
	  	length=Math.sqrt((x[0]-x[3])*(x[0]-x[3])+(y[0]-y[3])*(y[0]-y[3]));
		//Calculating length by formula ((x2-x1)^2 + (y2-y1)^2) and square root of this
	}

		public void Breadth()
    	{
		if(Math.sqrt((x[0]-x[1])*(x[0]-x[1])+(y[0]-y[1])*(y[0]-y[1]))==0)
	  	{
		System.out.println("Invalid breadth");
		System.exit(0);
	  	}
	  	breadth=Math.sqrt((x[0]-x[1])*(x[0]-x[1])+(y[0]-y[1])*(y[0]-y[1]));
		//Calculating breadth by formula ((x2-x1)^2 + (y2-y1)^2) and square root of this
   	}

	    	public boolean CheckRectangle()
    	{
		double first =Math.ceil(Math.sqrt((x[0]-x[2])*(x[0]-x[2])+(y[0]-y[2])*(y[0]-y[2])));
		double second=Math.ceil(Math.sqrt((x[1]-x[3])*(x[1]-x[3])+(y[1]-y[3])*(y[1]-y[3])));
		//Math.ceil is used for approximation of values so that a minute difference in length and breadth is not considered
		if(first==second)
		return true;
		else
		return false;
	}

	   public void verifyValues(double side)
   {
	   try
	   {
	   	if(side>20.0)
	   	throw new CustomException("Invalid value");
	   	}
	   	catch(CustomException e)
	   	{
		System.out.println(e.getMessage());
		System.exit(1);
	    }
	}

	//Function for checking if rectangle is a square
	public boolean CheckSquare()
	{
		if(length==breadth)
		return true;
		else
		return false;
	}

	//Calling area function of parent class
   public double area()
   	{
		double area=super.area();
   		return area;
   	}

	//Calling perimeter function of parent class
   	public double perimeter()
   	{
		double myPerimeter = super.perimeter();
   		return myPerimeter;
	}

	   public static void main(String args[])
   	{
		Scanner scan=new Scanner(System.in);
		double lengtharr[]=new double[4];
		double breadtharr[]=new double[4];
		System.out.print("Enter four coordinates in the form of (x,y): ");

		for(int i=0;i<4;++i)
		{
		lengtharr[i]=scan.nextDouble();
		breadtharr[i]=scan.nextDouble();
	    	}


		MyShape shape1 = new MyShape(lengtharr,breadtharr);

		//Checking if shape is a Rectangle
		boolean check = shape1.CheckRectangle();
   		if(check==false)
   		{
   		System.out.println("This is not a rectangle");
   		System.exit(1);
	    	}
		else
		{
		System.out.println("This is a rectangle");
		}

				//Calculating length , breadth, area and perimeter of the rectangle
		shape1.Length();
	    	shape1.Breadth();
	    	System.out.println("The area is: "+ shape1.area());
	    	System.out.println("The perimeter is: "+ shape1.perimeter());

		//Checking if the rectangle is square
		check = shape1.CheckSquare();
	    	if(check==false)
	    	{
   	      	System.out.println("The rectangle is not a square");
	    	}
		else
		{
		System.out.println("The rectangle is a square");
	    	}
	    	scan.close();
   	}
}