Develop Reference

i want to display every number entered in my while loop.so how can i do this

must create a java application that will determine and display sum of numbers as entered by the user.The summation must take place so long the user wants to.when program ends the summation must be displayed as follows
e.g say the user enters 3 numbers
10 + 12+ 3=25
and you must use a while loop

Here's a function to do just that. Just call the function whenever you need.
Ex: System.out.println(parseSum("10 + 12+ 3")) → 25
public static int parseSum(String input) {
// Removes spaces
input = input.replace(" ", "");
int total = 0;
String num = "";
int letter = 0;
// Loop through each letter of input
while (letter < input.length()) {
// Checks if letter is a number
if (input.substring(letter, letter+1).matches(".*[0-9].*")) {
// Adds that character to String
num += input.charAt(letter);
} else {
// If the character is not a number, it turns the String to an integer and adds it to the total
total += Integer.valueOf(num);
num = "";
}
letter++;
}
total += Integer.valueOf(num);
return total;
}
The while loop is essentially a for loop though. Is there a specific reason why you needed it to be a while loop?

There is a lot of ways to achieve this. Here an example of code that could be improve (for example by catching an InputMismatchException if the user doesn't enter a number).
Please for the next time, post what you have tried and where you stuck on.
public static void main (String[] args) {
boolean playAgain = true;
while(playAgain) {
Scanner sc = new Scanner(System.in);
System.out.println("Please enter the first number : ");
int nb1 = sc.nextInt();
System.out.println("Ok! I got it! Please enter the second number : ");
int nb2 = sc.nextInt();
System.out.println("Great! Please enter the third and last number : ");
int nb3 = sc.nextInt();
int sum = nb1+nb2+nb3;
System.out.println("result==>"+nb1+"+"+nb2+"+"+nb3+"="+sum);
boolean validResponse = false;
while(!validResponse) {
System.out.println("Do you want to continue ? y/n");
String response = sc.next();
if(response.equals("n")) {
System.out.println("Thank you! see you next time :)");
playAgain = false;
validResponse = true;
} else if(response.equals("y")) {
playAgain = true;
validResponse = true;
} else {
System.out.println("Sorry, I didn't get it!");
}
}
}
}

Java Sum of numbers until string is entered

i've just started java programming and was wondering on how to approach or solve this problem i'm faced with.
I have to write a program that asks a user for a number and continually sums the numbers inputted and print the result.
This program stops when the user enters "END"
I just can't seem to think of a solution to this problem, any help or guidance throughout this problem would be much appreciated and would really help me understand problems like this. This is the best i could do
public static void main(String[] args) {
Scanner scan = new Scanner(System.in);
while (true) {
System.out.print("Enter a number: ");
int x = scan.nextInt();
System.out.print("Enter a number: ");
int y = scan.nextInt();
int sum = x + y;
System.out.println("Sum is now: " + sum);
}
}
}
The output is supposed to look like this:
Enter a number: 5
Sum is now: 5
Enter a number: 10
Sum is now: 15
Enter a number: END

One solution would be to not use the Scanner#nextInt() method at all but instead utilize the Scanner#nextLine() method and confirm the entry of the numerical entry with the String#matches() method along with a small Regular Expression (RegEx) of "\d+". This expression checks to see if the entire string contains nothing but numerical digits. If it does then the matches() method returns true otherwise it returns false.
Scanner scan = new Scanner(System.in);
int sum = 0;
String val = "";
while (val.equals("")) {
System.out.print("Enter a number (END to quit): ");
val = scan.nextLine();
// Was the word 'end' in any letter case supplied?
if (val.equalsIgnoreCase("end")) {
// Yes, so break out of loop.
break;
}
// Was a string representation of a
// integer numerical value supplied?
else if (val.matches("\\-?\\+?\\d+")) {
// Yes, convert the string to integer and sum it.
sum += Integer.parseInt(val);
System.out.println("Sum is now: " + sum); // Display Sum
}
// No, inform User of Invalid entry
else {
System.err.println("Invalid number supplied! Try again...");
}
val = ""; // Clear val to continue looping
}
// Broken out of loop with the entry of 'End"
System.out.println("Application ENDED");
EDIT: Based on Comment:
Since since an integer can be signed (ie: -20) or unsigned (ie: 20) and the fact that an Integer can be prefixed with a + (ie: +20) which is the same as unsigned 20, the code snippet above takes this into consideration.

Do it like this:
public static void main(String[] args) throws Exception {
int sum = 0;
Scanner scan = new Scanner(System.in);
while (scan.hasNext()) {
System.out.print("Enter a number: ");
if (scan.hasNextInt())
sum += scan.nextInt();
else
break;
System.out.println("Sum is now: " + sum);
}
System.out.print("END");
}
This will end if the input is not a number (int).
As pointed out in the comments, if you want the program to stop when the user specifically enters "END", change the else-statement to:
else if (scanner.next().equals("END"))
break;

Store user input in array multiple times

I'm working on a project which...
Allows the user to input 4 numbers that are then stored in an array for later use. I also want every time the user decided to continue the program, it creates a new array which can be compared to later to get the highest average, highest, and lowest values.
The code is not done and I know there are some things that still need some work. I just provided the whole code for reference.
I'm just looking for some direction on the arrays part.
*I believe I am supposed to be using a 2-D array but I'm confused on where to start. If I need to explain more please let me know. (I included as many comments in my code just in case.)
I tried converting the inputDigit(); method to accept a 2-D array but can't figure it out.
If this question has been answered before please redirect me to the appropriate link.
Thank you!
package littleproject;
import java.util.InputMismatchException;
import java.util.Scanner;
public class littleProject {
public static void main(String[] args) {
// Scanner designed to take user input
Scanner input = new Scanner(System.in);
// yesOrNo String keeps while loop running
String yesOrNo = "y";
while (yesOrNo.equalsIgnoreCase("y")) {
double[][] arrayStorage = inputDigit(input, "Enter a number: ");
System.out.println();
displayCurrentCycle();
System.out.println();
yesOrNo = askToContinue(input);
System.out.println();
displayAll();
System.out.println();
if (yesOrNo.equalsIgnoreCase("y") || yesOrNo.equalsIgnoreCase("n")) {
System.out.println("You have exited the program."
+ " \nThank you for your time.");
}
}
}
// This method gets doubles and stores then in a 4 spaced array
public static double[][] inputDigit(Scanner input, String prompt) {
// Creates a 4 spaced array
double array[][] = new double[arrayNum][4];
for (int counterWhole = 0; counterWhole < array.length; counterWhole++){
// For loop that stores each input by user
for (int counter = 0; counter < array.length; counter++) {
System.out.print(prompt);
// Try/catch that executes max and min restriction and catches
// a InputMismatchException while returning the array
try {
array[counter] = input.nextDouble();
if (array[counter] <= 1000){
System.out.println("Next...");
} else if (array[counter] >= -100){
System.out.println("Next...");
} else {
System.out.println("Error!\nEnter a number greater or equal to -100 and"
+ "less or equal to 1000.");
}
} catch (InputMismatchException e){
System.out.println("Error! Please enter a digit.");
counter--; // This is designed to backup the counter so the correct variable can be input into the array
input.next();
}
}
}
return array;
}
// This will display the current cycle of numbers and format all the data
// and display it appropriatly
public static void displayCurrentCycle() {
int averageValue = 23; // Filler Variables to make sure code was printing
int highestValue = 23;
int lowestValue = 23;
System.out.println(\n--------------------------------"
+ "\nAverage - " + averageValue
+ "\nHighest - " + highestValue
+ "\nLowest - " + lowestValue);
}
public static void displayAll() {
int fullAverageValue = 12; // Filler Variables to make sure code was printing
int fullHighestValue = 12;
int fullLowestValue = 12;
System.out.println(" RESULTS FOR ALL NUMBER CYCLES"
+ "\n--------------------------------"
+ "\nAverage Value - " + fullAverageValue
+ "\nHighest Value - " + fullHighestValue
+ "\nLowest Value - " + fullLowestValue);
}
// This is a basic askToContinue question for the user to decide
public static String askToContinue(Scanner input) {
boolean loop = true;
String choice;
System.out.print("Continue? (y/n): ");
do {
choice = input.next();
if (choice.equalsIgnoreCase("y") || choice.equalsIgnoreCase("n")) {
System.out.println();
System.out.println("Final results are listed below.");
loop = false;
} else {
System.out.print("Please type 'Y' or 'N': ");
}
} while (loop);
return choice;
}
}

As far as is understood, your program asks the user to input four digits. This process may repeat and you want to have access to all entered numbers. You're just asking how you may store these.
I would store each set of entered numbers as an array of size four.
Each of those arrays is then added to one list of arrays.
A list of arrays in contrast to a two-dimensional array provides the flexibility to dynamically add new arrays.
We store the digits that the user inputs in array of size 4:
public double[] askForFourDigits() {
double[] userInput = new double[4];
for (int i = 0; i < userInput.length; i++) {
userInput[i] = /* ask the user for a digit*/;
}
return userInput;
}
You'll add all each of these arrays to one list of arrays:
public static void main(String[] args) {
// We will add all user inputs (repesented as array of size 4) to this list.
List<double[]> allNumbers = new ArrayList<>();
do {
double[] numbers = askForFourDigits();
allNumbers.add(numbers);
displayCurrentCycle(numbers);
displayAll(allNumbers);
} while(/* hey user, do you want to continue */);
}
You can now use the list to compute statistics for numbers entered during all cycles:
public static void displayAll(List<double[]> allNumbers) {
int maximum = 0;
for (double[] numbers : allNumbers) {
for (double number : numbers) {
maximum = Math.max(maximum, number);
}
}
System.out.println("The greatest ever entered number is " + maximum);
}

can I print something inside of the round brackets in while loop with the condition?

I was playing with this code...
import java.util.Scanner;
class plus
{
public static void main(String[] args)
{
Scanner scan = new Scanner(System.in);
do{
System.out.print("Youe Value: ");
long tobe = scan.nextLong();
int total = 0;
String parsed = String.valueOf(tobe);
for(int i = 0; i < parsed.length(); i++) {
total += Character.getNumericValue(parsed.charAt(i));
}
System.out.println("Your Result: "+ total);
}
while(scan.hasNextLong());
}
}
The output should prompt for a number then process it and print as Result.
and then again with another input if that's a integer(long)
but the condition in while loop scan.hasnextLong takes input itself and process it and the output is like this-
Your Value: Your Result: n
but the expected output is like this-
Your Value: m
Your Result: n
as like the first time. tobe does not seems taking input after first time. its just using what give in loop condition to check if thats a integer. more clearly the program prompt before printing Your Value: and use this value in tobe.
So i wanted to print inside of while loop condion
somewhere in this line with condition inside the round brackets
while(scan.hasNextLong())
so it print and prompt like I wanted;

I changed your code so the scanner gets a String input.
The while condition then checks if it contains only numbers. It does that by calling .matches() on the input, which tries to match the input string with the Regular Expression \d+. This expression matches a series of one or more digits. \d is for a digit, + is a quantifier. You can learn about and play with Regular Expressions on sites like RegExr.
Scanner scan = new Scanner(System.in);
String input;
System.out.print("Your Value: ");
while ((input = scan.nextLine()).matches("\\d+")){
int total = 0;
for(int i = 0; i < input.length(); i++) {
total += Character.getNumericValue(input.charAt(i));
}
System.out.println("Your Result: "+ total);
System.out.println("\nYour Value: ");
}
System.out.println("\nTHE END.");
scan.close();

You're triyng to print a value before initializing it. If you use print instead of println the next output will be on the same line.
public static void main(String[] args)
{
Scanner scan = new Scanner(System.in);
do{
long tobe = scan.nextLong();
System.out.println("Your Value: " + tobe);
int total = 0;
String parsed = String.valueOf(tobe);
for(int i = 0; i < parsed.length(); i++) {
total += Character.getNumericValue(parsed.charAt(i));
}
System.out.println("Your Result: "+ total);
}
while(scan.hasNextLong());
}

Replace while(scan.hasNextLong()); with while(scan.hasNextLine());

Calculate an Average from user input of five to ten numbers using Methods

My assignment requires me to prompt a user for 5 to 10 numbers and then calculate the average of those numbers. I also have to use methods to do so. My question is, how do I get the program to calculate the average if exactly if I'm not sure if they will enter 5 or 10 numbers? Below is what I have so far, I'm also having a little trouble understanding how to get the methods to execute in the main method but I think I have the actual method ideas right.
It was suggested that I format as reflected below, but my problem here is that it does not print anything after the user inputs its numbers, can anyone see what I'm missing? I'm thinking maybe I did something wrong in the main method?
public class AverageWithMethods {
public static void main(String[] args) {
String userNumbers = getUserNums();
double average = userNumAvg(userNumbers);
printAverage(0, userNumbers);
}
public static String getUserNums() {
Scanner in = new Scanner(System.in);
String userNumInput = "";
System.out.print("Please enter five to ten numbers separated by spaces: ");
userNumInput = in.nextLine();
return userNumInput;
}
public static double userNumAvg(String userNumInput) {
Scanner in = new Scanner(System.in);
Scanner line = new Scanner(in.nextLine());
double count = 0;
double average = 0.0;
double sum =0;
while (in.hasNextDouble()) {
count++;
sum = line.nextDouble();
}
if (count != 0) {
average = sum / count;
count = Double.parseDouble(userNumInput);
}
return average;
}
public static void printAverage(double average, String userNumInput) {
System.out.printf("The average of the numbers " + userNumInput + " is %.2f", average);
}
}

count how many spaces there are in your string. You can do this either by looping and checking the char value or you can do a replace on the string and compare the size of the new String
e.g.
String fiveNums = "1 2 3 4 5";
String noSpaces = fiveNums.replace(" ", "");
System.out.println(fiveNums.length() - noSpaces.length());

From your first section of code I am making the assumption all the numbers are entered on a single line all at once.
My question is, how do I get the program to calculate the average if exactly if I'm not sure if they will enter 5 or 10 numbers?
The Scanner object you are using has a method hasNextInt() so you can construct a simple while loop to figure out how many numbers there are.
Scanner line = new Scanner(in.nextLine()); // Feed line into scanner
int numbers = 0;
double total = 0.0;
while(in.hasNextInt()) { // read all the numbers
numbers++;
total += line.nextDouble();
}
line.close(); // Good habit
You can then compute your average with all this information:
double avg = total/numbers;
Notes:
Making total a double to avoid integer math when computing the average. There are obviously other ways to avoid integer math and I can include more if you would like.
I use a second Scanner with a String parameter of in.nextLine() because if you skip that step, the code won't terminate when reading a continuous input stream such as a console/terminal. This is because there will be a next int possible since the terminal is still accepting input.

When you want to understand how many numbers input the user, you can:
String[] userNumInput = in.nextLine().split(" ");
int quantity = userNumInput.length;
User input quantity numbers.
Here is one of the possible ways to do from your original code:
import java.util.Scanner;
public class GetAverage {
public GetAverage() {
String getStr = getUserNums();
double result = userAvg(getStr);
printAverage(result, getStr);
}
public String getUserNums() {
Scanner in = new Scanner(System.in);
System.out.println("Please enter five to ten numbers separated by spaces: ");
return in.nextLine();
}
public static double userAvg(String str) {
String[] arr = str.split(" ");
double sum = 0.0;
double average = 0.0;
for (int i = 0; i < arr.length; i++) {
sum += Integer.parseInt(arr[i]);
}
if (arr.length > 0) {
average = sum / arr.length;
}
return average; // how do I get the program to count what to divide by since user can input 5- 10?
}
public static void printAverage(double average, String userNumInput) {
System.out.printf("The average of the numbers " + userNumInput + "is %.2f", average);
}
public static void main(String[] args) {
new GetAverage();
}
}
OUTPUT:
Please enter five to ten numbers separated by spaces:
5 7 8 9 6 3 2 4
The average of the numbers 5 7 8 9 6 3 2 4is 5.50