Question

1. Write a method named RandomDoubles that takes a parameter N as its argument and generates N random double values where each double value is a random double between 0.0 and 0.9999…. (i.e. simply use Math.random()) and save these double values into a file named doubles.txt.(java please)

Next, write the following method that returns the number of digits in the fractional part of a double value. For example, 12.345 has 3 digits in the fractional part, 1.2345 has 4 digits in the fractional part, 12.0 has 0 digits in the fractional part i.e. this double value is essentially an integer.

You should round the fractional part (not the whole value, what happens if you round the whole value? Test it and see) of the value parameter so that it contains a maximum of 6 decimal places and hence the maximum possible value returned by the following method is 6.

public static int FractionDigits(double value)
               

Here are some sample usage of this method along with their corresponding outputs.

System.out.println(FractionDigits(12.0)); //output: 0

System.out.println(FractionDigits(12.1230000)); //output: 3

System.out.println(FractionDigits(12.01204000)); //output: 5

System.out.println(FractionDigits(12.12345678)); //output: 6

System.out.println(FractionDigits(12.99999999)); //output: 0

System.out.println(FractionDigits(12.99999919)); //output: 6

Test this FractionDigits method on the values you placed in doubles.txt by reading the double values from that file and outputting the FractionDigits on the screen.

Answer 1

Thanks for the question.

Here is the completed code for this problem. Comments are included so that you understand whats going on. Let me know if you have any doubts or if you need anything to change.

Thank You !!

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import java.io.*;
import java.util.Random;
import java.util.Scanner;

public class Fractions {

    // input and output file
    private static final String FILE = "doubles.txt";

    // takes in the number of doubles to generate and writes them to the file
    public static void randomDouble(int numberCount) throws IOException {

        PrintWriter writer = new PrintWriter(new FileWriter(FILE));
        Random random = new Random();
        for (int i = 1; i <= numberCount; i++) {
            writer.write(String.valueOf(random.nextDouble()) + "\r\n");
        }
        writer.flush();
        writer.close();
        System.out.println("file created successfully.");
    }

    // returns the number of digits in the fractional part
    public static int FractionDigits(double value) {

        int integerPart = (int) (value);
        value -= integerPart;
        value = (double) (Math.round(value * 1000000) / 1000000.0);
        integerPart = (int) (value);
        if (value - integerPart == 0) return 0;
        else return String.valueOf(value).length() - 2;

    }


    public static void main(String[] args) {
        try {
            randomDouble(10);
            displayFractionDigits();
        } catch (IOException e) {
            System.out.println("Unable to write to file: " + FILE);
        }


        System.out.println(FractionDigits(12.0)); //output: 0
        System.out.println(FractionDigits(12.1230000)); //output: 3
        System.out.println(FractionDigits(12.01204000)); //output: 5
        System.out.println(FractionDigits(12.12345678)); //output: 6
        System.out.println(FractionDigits(12.99999999)); //output: 0
        System.out.println(FractionDigits(12.99999919)); //output: 6


    }

    // method reads the numbers from doubles.txt file
    private static void displayFractionDigits() throws FileNotFoundException {

        Scanner inputFile = new Scanner(new File(FILE));
        while (inputFile.hasNext()) {
            double number = Double.parseDouble(inputFile.nextLine());
            int digits = FractionDigits(number);
            System.out.println("Number: " + number + " contains " + digits + " fractional parts.");
        }
        inputFile.close();

    }
}

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