Question

JAVA please!

Prime numbers are interesting numbers. A prime number is one that is only divisible by 1 and itself. For hundreds of years mathematicians have looked for the largest prime number. In the year 1456 the largest known prime was 8191. By the year 1588 it was a 6-digit number: 131,071. The famous mathematician Leonhard Euler discovered the 10-digit number 2,147,483,647 in 1772. Over the years larger and larger primes have been found. There are contests to find the largest prime. Over the years there have been prizes of $50,000, $100,000, and $150,000 awarded for finding the biggest prime number. Currently the largest prime number is 2^82,589,933 − 1 with 24,862,048 digits, found in December 2018. This project is to determine if a 10-digit phone number is a prime number. If the number is a prime number, then print a message to that effect. If the number is not a prime number, then print the prime factors of the number. Allow the user to continue entering numbers for as long as he or she wishes. We will discuss possible algorithms and determine the most efficient one to be used by everyone. This project is a two-part project. The first part is to write a program that will create a list of prime factors that can be stored in an ArrayList. This list will be sent to a file. The second part of the project is to write a program that will read from a file the list of prime factors created in part one and use it to determine if the phone number is prime and if not, what are its prime factors. The program will work with positive numbers up to 10 billion. The largest positive 32-bit integer is not large enough to hold a 10-digit phone number. The largest positive 32-bit integer is 2,147,483,647. To hold a 10-digit phone number we will need to use a long which is a 64-bit integer which has a positive range to 9,223,372,036,854,775,807. This code will read a long value: System.out.println("please enter a 10-digit phone number");

long phoneNumber = scan.nextLong();

This code will read the prime factors from the file and put them in an ArrayList.

while(scanFile.hasNextInt())

{

primeArray.add( scanFile.nextInt());

}

Answer 1

1 import java.io.*; import java.util.*; 2 3 4 public class PrimeDemo { 5 6 public static final String FACTORS_FILE = "factors.txt"; 7 8 // Method to create factors on file, you should call this method only once to create the factors file. static void printPrimesToFile() throws FileNotFoundException { 9 10 11 // Taking max 6 digit number, since our mob is 10 digits long hence factors can be restricted till square root only. List<Integer> nums = Intstream.rangeclosed(2, 100000).boxed().collect(collectors.toList()); 12 13 for (int index = 0; index < nums.size(); index++) { // Remove all numbers which are divisible by current number int curr = nums.get(index); nums = nums.stream().filter(x -> (x == curr || ~ % curr != 0)).collect(Collectors.toList()); بها // Now we have all the prime factors in list now. Printwriter writer = new Printwriter(new File(FACTORS_FILE)); for (int x : nums) { writer.println(x); } 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 writer.close(); } static void loadFactors(ArrayList<Integer> factors) throws FileNotFoundException { Scanner sc = new Scanner(new File(FACTORS_FILE)); while (sc. hasNextInt()) { factors.add(sc.nextInt()); } sc.close(); } 36 37 Run Debug public static void main(String[] args) throws FileNotFoundException { printPrimesToFile();

27 28 29 30 static void loadFactors (ArrayList<Integer> factors) throws FileNotFoundException { Scanner sc = new Scanner(new File(FACTORS_FILE)); while (sc.hasNextInt()) { factors.add(sc.nextInt()); 31 32 33 } sc.close(); } 34 35 36 37 38 39 Run | Debug public static void main(String[] args) throws FileNotFoundException { printPrimesToFile(); ArrayList<Integer> factors = new ArrayList<Integer>(); loadFactors(factors); 40 41 42 43 Scanner in = new Scanner(System.in); System.out.println("Enter mobile number: "); long mob = in.nextLong(); 44 45 46 47 boolean prime = true; for (int x : factors) { if (mob % x == 0) { prime = false; break; 48 49 } 50 51 } 52 53 54 55 56 57 58 59 60 if (prime) { System.out.println("Mobile number is prime"); } else { System.out.println("Mobile number is not prime"); } }

import java.io.*;

import java.util.*;

public class PrimeDemo {

    public static final String FACTORS_FILE = "factors.txt";

    // Method to create factors on file, you should call this method only once to create the factors file.

    static void printPrimesToFile() throws FileNotFoundException {

        // Taking max 6 digit number, since our mob is 10 digits long hence factors can be restricted till square root only.

        List<Integer> nums = IntStream.rangeClosed(2, 100000).boxed().collect(Collectors.toList());

        for (int index = 0; index < nums.size(); index++) {

            // Remove all numbers which are divisible by current number

            int curr = nums.get(index);

            nums = nums.stream().filter(x -> (x == curr || x % curr != 0)).collect(Collectors.toList());

        }

        // Now we have all the prime factors in list now.

        PrintWriter writer = new PrintWriter(new File(FACTORS_FILE));

        for (int x : nums) {

            writer.println(x);

        }

        writer.close();

    }

    static void loadFactors(ArrayList<Integer> factors) throws FileNotFoundException {

        Scanner sc = new Scanner(new File(FACTORS_FILE));

        while (sc.hasNextInt()) {

            factors.add(sc.nextInt());

        }

        sc.close();

    }

    public static void main(String[] args) throws FileNotFoundException {

        printPrimesToFile();

        ArrayList<Integer> factors = new ArrayList<Integer>();

        loadFactors(factors);

        Scanner in = new Scanner(System.in);

        System.out.println("Enter mobile number: ");

        long mob = in.nextLong();

        boolean prime = true;

        for (int x : factors) {

            if (mob % x == 0) {

                prime = false;

                break;

            }

        }

        if (prime) {

            System.out.println("Mobile number is prime");

        } else {

            System.out.println("Mobile number is not prime");

        }

    }

}

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