Challenges 1,2 and 5

ATBackendChallenge.iml

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+<?xml version="1.0" encoding="UTF-8"?>
+<module type="JAVA_MODULE" version="4">
+  <component name="NewModuleRootManager" inherit-compiler-output="true">
+    <exclude-output />
+    <content url="file://$MODULE_DIR$">
+      <sourceFolder url="file://$MODULE_DIR$/src" isTestSource="false" />
+    </content>
+    <orderEntry type="inheritedJdk" />
+    <orderEntry type="sourceFolder" forTests="false" />
+  </component>
+</module>

src/Calculations.java

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+
+import java.math.BigDecimal;
+import java.math.BigInteger;
+import java.util.ArrayList;
+
+public class Calculations {
+
+
+    private BigInteger oneBigint = new BigInteger("1");
+    private BigInteger zeroBigint = new BigInteger("0");
+    private BigInteger twoBigint = new BigInteger("2");
+    public Calculations() {
+    }
+
+    //A method to display Arraylists
+    public void displayArraylist(ArrayList<BigInteger> sourceList)
+    {
+        if ((sourceList.isEmpty()))
+        {
+            System.out.println("List is empty!");
+        }
+        else
+        {
+            for(int i = 0; i<sourceList.size(); i++)
+            {
+                BigInteger x = sourceList.get(i);
+                System.out.print(x +" ");
+            }
+        }
+        System.out.println();
+    }
+    //A function that takes an int n and returns a list of all prime numbers between 0 and n
+    public ArrayList<BigInteger> primeNumbersToN(BigInteger n)
+    {
+        ArrayList<BigInteger> primeNums = new ArrayList<>();
+        if(n.compareTo(new BigInteger("2"))>0)
+        {
+            for (BigInteger i = twoBigint; i.compareTo(n)<0;i=i.add(oneBigint))
+            {
+                if(isPrime(i))
+                {
+                    primeNums.add(i);
+                }
+            }
+        }
+        return primeNums;
+    }
+    private Boolean isPrime(BigInteger number)
+    {
+        if ((number.compareTo(oneBigint.add(BigInteger.ONE)))<0)
+        {
+            return false;
+        }
+        else if (number.equals(BigInteger.valueOf(2)) || number.equals(BigInteger.valueOf(3)))
+        {
+            return true;
+        }
+        else
+        {
+            BigInteger rootNumber = BigDecimal.valueOf(Math.sqrt(number.doubleValue())).toBigInteger();
+            for (BigInteger i = twoBigint; i.compareTo(rootNumber.add(oneBigint))<0;i=i.add(oneBigint))
+            {
+                if((number.remainder(i)).equals(zeroBigint))
+                {
+                    return false;
+                }
+            }
+            return true;
+        }
+    }
+
+    //A function that takes an Int n and returns a List of all the factorials of the numbers between 0 and n inclusive
+
+
+    public ArrayList<BigInteger> nFactorials(BigInteger n)
+    {
+        ArrayList<BigInteger> numberFactorials = new ArrayList<>();
+        if(n.compareTo(zeroBigint)>0)
+        {
+            for(BigInteger i = oneBigint; i.compareTo(n)<0;i=i.add(oneBigint))
+            {
+                BigInteger nFact = nFactorial(i);
+                numberFactorials.add(nFact);
+            }
+        }
+        return numberFactorials;
+    }
+    private BigInteger nFactorial(BigInteger number)
+    {
+        BigInteger multiplier = new BigInteger("1");
+        return computeFactorial(number,multiplier);
+    }
+    private BigInteger computeFactorial(BigInteger start, BigInteger result)
+    {
+        if(start.compareTo(zeroBigint)>0)
+        {
+            return computeFactorial(start.subtract(oneBigint), result.multiply(start));
+        }
+        return result;
+    }
+
+}

src/Main.java

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+import java.math.BigInteger;
+import java.util.ArrayList;
+import java.util.Scanner;
+
+public class Main {
+
+    public static Calculations calcs;
+
+    public static void main(String[] args)
+    {
+        calcs = new Calculations();
+        Scanner scanner =  new Scanner(System.in);
+
+        String yes;
+        do{
+            evaluateCalculations();
+            System.out.println("Enter 'y' to repeat operation: ");
+            yes = scanner.next();
+        }while (yes.equals("y") || yes.equals("Y"));
+    }
+
+    public static void evaluateCalculations()
+    {
+        Scanner scanner =  new Scanner(System.in);
+
+        BigInteger nPrimes, nFactorials;
+        do {
+            System.out.println("Enter a positive integer, n,  to evaluate Primes between 0 and n: ");
+            nPrimes = scanner.nextBigInteger();
+        }while (nPrimes.compareTo(BigInteger.ONE)<0);
+        listPrimes(nPrimes);
+        do {
+            System.out.println("Enter a positive integer to evaluate Factorials of integers between 0 and n: ");
+            nFactorials = scanner.nextBigInteger();
+        }while (nFactorials.compareTo(BigInteger.ONE) < 0);
+        listFactorials(nFactorials);
+
+    }
+
+    public static void listPrimes(BigInteger n)
+    {
+        ArrayList<BigInteger>  listOfPrimes = calcs.primeNumbersToN(n);
+        calcs.displayArraylist(listOfPrimes);
+    }
+
+    public static void listFactorials(BigInteger f)
+    {
+        ArrayList<BigInteger>  listOfFactorials = calcs.nFactorials(f);
+        calcs.displayArraylist(listOfFactorials);
+    }
+
+}

src/Person.java

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+public class Person {
+    private String name;
+    private int Age;
+
+
+    public Person() {
+    }
+
+    public int getAge() {
+        return Age;
+    }
+
+    public void setAge(int age) {
+        if (age<=0)
+        {
+            throw new IllegalArgumentException("The value of age should be positive.");
+        }
+        Age = age;
+    }
+
+    public String getName() {
+        return name;
+    }
+
+    public void setName(String name) {
+        this.name = name;
+    }
+}