Question

1. (Sum the digits in an integer) Write a method that computes the sum of the digits in an integer. Use the following method header:

public static int sumDigits(long n)

For example, sumDigits (234) returns 9 (2 + 3 + 4). (Hint: Use the % operator to extract digits, and the / operator to remove the extracted digit. For instance, to extract 4 from 234, use 234 % 10(= 4). To remove 4 from 234, use 234 / 10(= 23). Use a loop to repeatedly extract and remove the digit until all the digits are extracted. Write a test program that prompts the user to enter an integer and displays the sum of all its digits.

Sample run in console:

Enter a number:1982222

The sum of the digits for 1982222 is 26

Then in a different class (Display an integer reversed) Write a method with the following header to display an integer in reverse order.

  public static void reverse(int number)

For example, reverse (3456) displays 6543. Write a test program that prompts the user to enter an integer and displays its reversal.

sample run in console

enter an integer: 1231982

2891321

Answer 1

Java code for both functions:-

//importing the library
import java.io.*;
import java.util.*;

//Class having function to Sum the digits of numbers   
class SumNumber{
  
/* Function to get sum of digits */
public static void sumDigits(long n) {   
  
long sum = 0,k=n;
  
while (n != 0){
  
sum=sum+n%10;
n = n/10;
}
  
//printing the output
System.out.println("The sum of the digits for " + k + " is "+sum);
}   
  
}

//Class having function to print the reverse of givrn number
class ReverseNumber{

/* Function to print the reverse of givrn number */
public static void reverse(int number)
{
//reversed varibale used to store the reverse number
long reversed = 0;

while(number != 0)
{
long digit =number % 10;
reversed = reversed * 10 + digit;
number/= 10;
}
  
//printing the output
System.out.println(reversed);
}
}

public class printdata
{
public static void main(String[] args)
{
//scanner for scanning the value
Scanner sc=new Scanner(System.in);
  
//Enter the digit for sum of digit operation
System.out.println("enter an integer:");
long l=sc.nextInt();
//since SumNumber class have static functon we are not worried about defining the object of that class
SumNumber.sumDigits(l);
  
//Enter the digit for reversing the number
System.out.println("enter an integer:");
int n=sc.nextInt();
//since ReverseNumber class have static functon we are not worried about defining the object of that class
ReverseNumber.reverse(n);
  
}
}