Armstrong number in Java

Question

This is my code, it is not producing any output. As I have started my loop from 100 so according to the logic used I should get answer as 153. But nothing is coming. Please help.

// Program to find the first Angstrom Number and display it!
public static void main(String[] args) {
    int sum = 0;
    int y, z;
    System.out.println("Starting program");

    for (int i = 100; i < 1000; i++) {
        sum += (i % 10) * (i % 10) * (i % 10);
        y = i / 10;
        sum += (y % 10) * (y % 10) * (y % 10);
        z = y / 10;
        sum += z * z * z;
        if (sum == i) {
            System.out.println("The first Angstrom number is " + i);
            break;
        }
    }
}

Answer 1

You should reset the sum in every step:

for (int i = 100; i < 1000; i++) {
    sum = 0;
    sum += (i%10) * (i%10) * (i%10);
    ....
}

Answer 2

You can find Armstrong number between two numbers by using this logic. Just change the values according to you need.

public class Armstrong {

    public static void main(String[] args) {

        int low = 999, high = 99999;

        for(int number = low + 1; number < high; ++number) {
            int digits = 0;
            int result = 0;
            int originalNumber = number;

            // number of digits calculation
            while (originalNumber != 0) {
                originalNumber /= 10;
                ++digits;
            }

            originalNumber = number;

            // result contains sum of nth power of its digits
            while (originalNumber != 0) {
                int remainder = originalNumber % 10;
                result += Math.pow(remainder, digits);
                originalNumber /= 10;
            }

            if (result == number)
                System.out.print(number + " ");
        }
    }
}

Output of this program is:
1634 8208 9474 54748 92727 93084

Answer 3

public static int Power(int out,int res)
{
    int count=res;
        int temp=1;
        while(count!=0)
        {
            temp=temp*out;
            count--;
        }
        return temp;
}
public static int count1(int num)
{
    int count=0;
    while(num!=0)
    {
        num=num/10;
        count++;
    }
    return count;
}
public static int isArmstrong(int num)
{
    int out;
    int sum=0;
    int res=count1(num);
    while(num!=0)
    {
        out=num%10;
        sum=sum+Power(out,res);
        num=num/10;
    }
    return sum;
}
public static void  main(String[] args)
{
    int start=10;
    int end=100000;
    for(int i=start;i<=end;i++)
    {
    int result=isArmstrong(i);
    if(result==i)
    {
        System.out.println(i);
    }

Answer 4

public class armstrongNumber 
{
 public void isArmstrong(String n)
  {
    char[] s=n.toCharArray();
    int size=s.length;
    int sum=0;
    
    for(char num:s)
    {int temp=1;
        int i=Integer.parseInt(Character.toString(num));
        for(int j=0;j<=size-1;j++)
        { temp *=i;}
        
        sum +=temp;
                
    }
    if(sum==Integer.parseInt(n))
    {
        System.out.println(n+" is an Armstrong Number");
    }
    else
    {
        System.out.println(n+" is not an Armstrong Number");
    }
  }
    public static void main(String[] args) 
    {
        armstrongNumber am= new armstrongNumber();
        am.isArmstrong("2");
        am.isArmstrong("153");
        am.isArmstrong("1634");
        am.isArmstrong("231");
    }

}

Answer 5

public class Armstrong {
    
    public static int findArmStrong(int x, int y) {
        if(x== getArmstrongSum(x)) return x;
        else if(y== getArmstrongSum(y)) return y;
        else return -1;
    }

    public static int getArmstrongSum(int num) {
        int pow = String.valueOf(num).length();
        return IntStream.iterate(num, i -> i / 10)
                .limit(pow)
                .map(i -> (int) Math.pow(i % 10, 3))
                .sum();
    }

    public static void main(String[] args) {
        
            System.out.println(findArmStrong(153, 154));
    }
}