Java || Compute The Sum From A String Of Integers & Display Each Number Individually

June 03, 2012 admin No comments

Here is a simple program, which was presented in a Java course. This program was used to introduce the input/output mechanisms which are available in Java. This assignment was modeled after Exercise 2.30, taken from the textbook “Java How to Program” (early objects) (9th Edition) (Deitel). It is the same exercise in both the 8th and 9th editions.

Our class was asked to make a program which prompts the user to enter a non-negative integer into the system. The program was supposed to then extract the digits from the inputted number, displaying them each individually, separated by a white space (” “). After the digits are displayed, the program was then supposed to display the sum of those digits to the screen. So for example, if the user inputted the number “39465,” the program would output the numbers 3 9 4 6 5 individually, and then the sum of 27.

REQUIRED KNOWLEDGE FOR THIS PROGRAM

How To Get String Input If/Else Statements Do/While Loops For Loops Methods (A.K.A "Functions") - What Are They? ParseInt - Convert String To Integer Substring Try/Catch





		
		
			Compute The Sum From A String Of Numbers
			
Java
			
			import java.util.Scanner;
import java.lang.Math;

public class SumFromString
{
   public static void main(String[] args)
   {
	   // declare variables
	   char question = 'n';
	   String userInput= " ";
	   Scanner cin = new Scanner(System.in);
	   
	   // display message to screen
	   System.out.println("nWelcome to My Programming Notes' Java Program.");
	   
	   do{// this is the start of the do/while loop	   
		   int sum = 0;
		   
		   // get data from the user
		   System.out.print("nEnter a non negative integer: ");
		   userInput = cin.nextLine();
		   
		   System.out.println("");
		   
		   // if the string isnt a number, dont compute the sum
		   if(!IsNumeric(userInput))
		   {
			   System.out.println(userInput+" is not a number...");
			   System.out.println("Please enter digits only!");	
		   }
		   
		   // if the string is a negative number, dont compute the sum
		   else if(IsNegative(userInput))
		   {
			   System.out.println(userInput+" is a negative number...");
			   System.out.println("Please enter positive digits only!");
		   }
		   
		   // if the string is a decimal number (i.e 19.87), dont compute the sum
		   else if(IsDecimal(userInput))
		   {
			   System.out.println(userInput+" is a decimal number...");
			   System.out.println("Please enter positive whole numbers only!");		  		
		   }
		   
		   // if everything else checks out OK, then compute the sum
		   else
		   {
			   System.out.print("The digits are: ");
			   sum = ComputeSum(userInput); 
			   System.out.println("and the sum is " + sum);
		   }
		   
		   // ask user if they want to enter more data
		   System.out.print("nDo you have more data for input? (Y/N): ");
		   String response = cin.nextLine();
		   response=response.toLowerCase();
		   question = response.charAt(0);
		   
		   System.out.println("n------------------------------------------------");
		   
	   }while(question == 'y');
	   
	   System.out.print("nBYE!n");
   }// end of main
   
   public static boolean IsNumeric(String str)  
   {// checks to see if a string is a number  
	   try
	   { 
		   Double.parseDouble(str);
		   return true;		   
	   }
	   catch(NumberFormatException nfe)
	   { 
		   return false;
	   }
   }// end of IsNumeric
   
   public static boolean IsNegative(String str)  
   {// checks to see if string is a negative number  
	   return Double.parseDouble(str) < 0;
   }// end of IsNegative   
   
   public static boolean IsDecimal(String str)  
   {// checks to see if string is a decimal number  
	   return (Math.floor(Double.parseDouble(str))) != Double.parseDouble(str);
   }// end of IsDecimal
   
   public static int ComputeSum(String userInput)
   {// displays each number individually & computes the sum of the string 
	   int sum = 0;
	   String[] temp = new String[userInput.length()];
	   
	   for(int counter=0; counter < userInput.length(); ++counter)
	   {
		   temp[counter] = userInput.substring(counter,counter+1); 
		   System.out.print(temp[counter] + " ");
		   sum = sum + Integer.parseInt(temp[counter]);
	   }
	   return sum;
   }// end of ComputeSum
}// http://programmingnotes.org/
			
				
					
				
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						import java.util.Scanner;
import java.lang.Math;
 
public class SumFromString
{
   public static void main(String[] args)
   {
	   // declare variables
	   char question = 'n';
	   String userInput= " ";
	   Scanner cin = new Scanner(System.in);
	   
	   // display message to screen
	   System.out.println("nWelcome to My Programming Notes' Java Program.");
	   
	   do{// this is the start of the do/while loop	   
		   int sum = 0;
		   
		   // get data from the user
		   System.out.print("nEnter a non negative integer: ");
		   userInput = cin.nextLine();
		   
		   System.out.println("");
		   
		   // if the string isnt a number, dont compute the sum
		   if(!IsNumeric(userInput))
		   {
			   System.out.println(userInput+" is not a number...");
			   System.out.println("Please enter digits only!");	
		   }
		   
		   // if the string is a negative number, dont compute the sum
		   else if(IsNegative(userInput))
		   {
			   System.out.println(userInput+" is a negative number...");
			   System.out.println("Please enter positive digits only!");
		   }
		   
		   // if the string is a decimal number (i.e 19.87), dont compute the sum
		   else if(IsDecimal(userInput))
		   {
			   System.out.println(userInput+" is a decimal number...");
			   System.out.println("Please enter positive whole numbers only!");		  		
		   }
		   
		   // if everything else checks out OK, then compute the sum
		   else
		   {
			   System.out.print("The digits are: ");
			   sum = ComputeSum(userInput); 
			   System.out.println("and the sum is " + sum);
		   }
		   
		   // ask user if they want to enter more data
		   System.out.print("nDo you have more data for input? (Y/N): ");
		   String response = cin.nextLine();
		   response=response.toLowerCase();
		   question = response.charAt(0);
		   
		   System.out.println("n------------------------------------------------");
		   
	   }while(question == 'y');
	   
	   System.out.print("nBYE!n");
   }// end of main
   
   public static boolean IsNumeric(String str)  
   {// checks to see if a string is a number  
	   try
	   { 
		   Double.parseDouble(str);
		   return true;		   
	   }
	   catch(NumberFormatException nfe)
	   { 
		   return false;
	   }
   }// end of IsNumeric
   
   public static boolean IsNegative(String str)  
   {// checks to see if string is a negative number  
	   return Double.parseDouble(str) < 0;
   }// end of IsNegative   
   
   public static boolean IsDecimal(String str)  
   {// checks to see if string is a decimal number  
	   return (Math.floor(Double.parseDouble(str))) != Double.parseDouble(str);
   }// end of IsDecimal
   
   public static int ComputeSum(String userInput)
   {// displays each number individually & computes the sum of the string 
	   int sum = 0;
	   String[] temp = new String[userInput.length()];
	   
	   for(int counter=0; counter < userInput.length(); ++counter)
	   {
		   temp[counter] = userInput.substring(counter,counter+1); 
		   System.out.print(temp[counter] + " ");
		   sum = sum + Integer.parseInt(temp[counter]);
	   }
	   return sum;
   }// end of ComputeSum
}// http://programmingnotes.org/

QUICK NOTES:
The highlighted lines are sections of interest to look out for.

The code is heavily commented, so no further insight is necessary. If you have any questions, feel free to leave a comment below.

Once compiled, you should get this as your output

Welcome to My Programming Notes' Java Program.
Enter a non negative integer: 0 The digits are: 0 and the sum is 0 Do you have more data for input? (Y/N): y ------------------------------------------------ Enter a non negative integer: 39465 The digits are: 3 9 4 6 5 and the sum is 27 Do you have more data for input? (Y/N): y ------------------------------------------------ Enter a non negative integer: H3ll0 W0rld H3ll0 W0rld is not a number... Please enter digits only! Do you have more data for input? (Y/N): y ------------------------------------------------ Enter a non negative integer: -98 -98 is a negative number... Please enter positive digits only! Do you have more data for input? (Y/N): y ------------------------------------------------ Enter a non negative integer: 19.87 19.87 is a decimal number... Please enter positive whole numbers only! Do you have more data for input? (Y/N): n ------------------------------------------------
BYE!

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Posted in: Console, Java Tags: do/while loop, for loop, functions, java, string

Java || Compute The Sum From A String Of Integers & Display Each Number Individually

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