Comparer.java

/** This class is used to test whether two floating-point numbers are the same. */ public class Comparer { . . . /** Creates a Comparer object to determine if two floating-point numbers are approximately the same. @param d the number of significant digits in the comparison */ public Comparer(int d) { . . . } /** Tests whether two numbers are close to each other. @param x1 the first number @param x2 the second number @return true if the two numbers differ by less than the number of significant digits */ public boolean areClose(double x1, double x2) { . . . } /** Tests whether two numbers round to the same value. @param x1 the first number @param x2 the second number @return true if the two numbers, when rounded to the number of significant digits, yield the same value */ public boolean roundToSame(double x1, double x2) { . . . } }

Use the following file:

NumberChecker.java

import java.util.Scanner;

/**
   This program checks whether two floating-point numbers are almost the same.
*/
public class NumberChecker
{
   public static void main(String[] args)
   {
      Comparer c = new Comparer(2);
      Scanner in = new Scanner(System.in);
      
      System.out.println("Enter two floating-point numbers:");
      double x1 = in.nextDouble();
      double x2 = in.nextDouble();

      System.out.print("They are ");
      if (c.roundToSame(x1, x2))
         System.out.print("the same ");
      else
         System.out.print("different ");
      System.out.println("when rounded to two decimal places.");
      System.out.print("They differ by ");
      if (c.areClose(x1, x2))
         System.out.print("less than ");
      else
         System.out.print("at least ");
      System.out.println("0.01.");
   }
}