Forward Driver

import java.util.Scanner;     // importing the Scanner class of the 'util' package to accept necessary inputs from the user
import NewtonInterpolation.*;   // importing the created package which contains the methods to accept and calculate the process

class InvalidNodeException extends Exception
{
	// class to deal with the exception of the 'pivot' node not lying between the interpolating points
}

class InvalidStepLengthException extends Exception
{
	// class to deal with the exception of the 'step-length' not being uniform
}

public class ForwardDriver 
{    
	public static void main(String[] args) 
	{    // start of main
		Scanner obj=new Scanner(System.in);   //creating object of the scanner class
		// declaring and initializing necessary variables
		double x[],y[][],pivot=0,h,temp;
		int n;
		boolean check=true;     
		System.out.println("\nPlease enter number of nodes...\n");
		n=obj.nextInt();      // accepting from the user the number of nodes to be inserted
		// creating the arrays 
		x=new double[n];
		y=new double[n][n];     
		
		for(int loop=0;loop<n;++loop)
		{
			System.out.print("\nEnter the value of x"+loop+": ");
			x[loop]=obj.nextDouble();   // accepting interpolating points
			System.out.print("\nEnter the value of y"+loop+": ");
			y[0][loop]=obj.nextDouble();  // accepting corresponding functional values
		}
		h=x[1]-x[0];  // calculating step-length
		h=Double.parseDouble(String.format("%.1f",h));   // for some inputs the floating point representations can hamper the desired result; so setting precision for such floating point numbers
		
		System.out.println("\nEnter x for finding f(x): ");
		pivot=obj.nextDouble();   // accepting the point at which the functional value is required
		try
		{
			if(pivot<x[0] || pivot>x[n-1])  // if condition to check if the user given point is an extrapolating point
			{
				check=false;  // changing the value of the check variable to keep a note that an exception has taken place
				InvalidNodeException ine=new InvalidNodeException();
				throw ine;
			}
		}
		catch(InvalidNodeException obj1)  // corresponding catch block
		{
			System.out.println(obj1);  // print exception
		}
		try
		{
			for(int loop=0;loop<n-1;++loop)
			{
				temp=x[loop+1]-x[loop];
				temp=Double.parseDouble(String.format("%.1f",temp));        // for some inputs the floating point representations can hamper the desires result; so setting precision for such floating point numbers
				if(temp!=h)  // if condition to check if the interpolating points are not equi-space
				{
					check=false;   // changing the value of the check variable to keep a note that an exception has taken place
					InvalidStepLengthException iine=new InvalidStepLengthException();
					throw iine;
				}
			}
		}
		catch(InvalidStepLengthException obj2)  // corresponding catch block
		{
			System.out.println(obj2); // print exception
		}
		if(check)   // if no exception has occurred
		{
			Forward forward=new Forward(x,y,n,pivot);  // create an object of the 'Forward' class and pass the accepted inputs through the parameterized constructor
			forward.forwardCal();  // call the method to perform Newton's Forward Interpolation using the recently object created
		}
		else  // if exception has occurred
		{
			System.out.println("\nINHERENT ERROR.\n");    // there are some errors in the entered entries
		}
	}

}