I'm trying to write a program that asks the user if they want to enter a real number. If yes, then prompt the user to enter a number. Keep prompting for number inputs until user says "no." Once this happens, output the average of the numbers entered.
I think I'm stuck trying to implement a string for the sentinel value. I want the sentinel value to be "no." But with this last attempt I have here, when I enter "yes" I get an InputMismatchException. Also, not sure if this is a job for do/while or just while. Kind of new to all this and not sure how to go about this, as we don't have examples of using strings for sentinels.
public static void main(String[] args) {
int count = 0;
float total = 0;
float inputNumber;
Scanner scan = new Scanner ( System.in );
System.out.println("Want to enter a number?");
String reply = "";
inputNumber = scan.nextFloat();
do {
reply = scan.nextLine();
if (reply.equalsIgnoreCase("yes")) {
System.out.println("Enter a number > ");
total+= inputNumber ;
count++ ;
System.out.println("Enter another number, or " +
"enter \"no\" to terminate > " );
inputNumber = scan.nextFloat();
}
}
while (! reply.equalsIgnoreCase("no")) ;
if (count != 0) {
System.out.println("The average of the numbers is " +
(total / count));
}
}
}
Remove first inputNumber = scan.nextFloat();
Fix loop.
Add scan.nextLine() after scan.nextFloat()
public static void main(String[] args) {
int count = 0;
float total = 0f;
float inputNumber = 0f;
Scanner scan = new Scanner ( System.in );
System.out.println("Want to enter a number?");
String reply = scan.nextLine();
while (reply.equalsIgnoreCase("yes")) {
System.out.println("Enter a number > ");
inputNumber = scan.nextFloat();
scan.nextLine();
total += inputNumber;
count++;
System.out.println("Enter another number, or enter \"no\" to terminate > ");
reply = scan.nextLine();
}
if (count != 0) {
System.out.println("The average of the numbers is " + (total / count));
}
}
EDIT
public static void main(String[] args) {
int count = 0;
float total = 0f;
float inputNumber = 0f;
Scanner scan = new Scanner ( System.in );
System.out.println("Want to enter a number?");
String reply = scan.nextLine();
if (!reply.equalsIgnoreCase("yes"))
return;
System.out.println("Enter a number > ");
while (!reply.equalsIgnoreCase("no")) {
reply = scan.nextLine();
try {
inputNumber = Float.parseFloat(reply);
} catch (NumberFormatException e) {
continue;
}
total += inputNumber;
count++;
System.out.println("Enter another number, or enter \"no\" to terminate > ");
}
if (count != 0) {
System.out.println("The average of the numbers is " + (total / count));
}
}
Related
Ask the user to "Input a number: " 4 times.
If the input is not a number, ask again.
Output "success." after they have entered 4 numbers.
Please answer this code for me using while, if, if else and do statements.
int counter; System.out.print("Input a number: ");
while(!(scan.hasNextInt()));{
for (int i = 0; i < 3; i++){
scan.next();
System.out.print("Input a number: ");
if (!(pass.equals(pass2))) {
counter++;
} else if (!(scan.hasNextInt())) {
}
}
if (counter >= 2) {
System.out.println("Input a number: ");
}
} else if (!(scan.hasNextInt())) { System.out.println("success."); }
This is very basic stuff but I am struggling.
int[] inputIntegers = new int[4]; // Array to save input
Scanner scan = new Scanner(System.in);
int counter = 0;
while(counter < 4) {
System.out.println("Input a number: ");
String input = scan.next();
if(input.matches("[-]?[0-9]*")){ // Checking, if input is an integer
inputIntegers[counter]=Integer.parseInt(input); // Persing string to integer
counter++;
} else {
System.out.println("Input is not an integer");
}
}
System.out.println("Success");
scan.close(); //Do not forget do close scanner
I'm trying to make code that asks the user to enter 10 numbers and subtracts them all. This is what i have so far. I think i have the general layout all set but i dont know what to do with the rest
import java.util.Scanner;
public class subnumbs
{
int dial;
int[] num = new int [10];
Scanner scan = new Scanner(System.in);
public void go()
{
int q=0;
dial = 10;
while (q != 0)
{
System.out.println("type numb: ");
int newinput = scan.nextInt();
q+=newInteger;
dial = cdial + 1;
}
return q;
}
}
System.out.printIn("Enter Integer: ");
int newInteger = scan.nextLine();
While (newInteger >= 0){
System.out.println("Re-enter Integer (must be negative): ");
newInteger = scan.nextLine();
}
n+=newInteger;
Counter = counter - 1;
return n;
this is one way to ensure inly negative numbers, only count down and add it if it was negative ...
while (counter != 0)
{
System.out.println("Enter Integer: ");
int newInteger = scan.nextInt();
if(newInteger < 0) {
n+=newInteger;
counter -= 1;
}
else {
System.out.println("must be negative integer, please try again: ")
{
}
In general, to ensure an input you have to evaluate it at the point where you are getting the input
I am wishing to prompt the user again if a double outside of the accepted range (0-100) is input, until the input is valid. When the input is considered valid, I am wanting to return correct input value, yet, returned instead is the first incorrect value. How can I return the correct input, as accepted by the if statement?? Many thanks!
public class examscore {
public static void main (String[] args) {
Scanner console = new Scanner(System.in);
double sumfin = finalscore(console);
System.out.println(sumfin); // if user input is initially invalid, but then corrected, the first, incorrect, value is printed
}
public static double finalscore (Scanner console) {
System.out.println();
System.out.println("Input final exam score: ");
while(!console.hasNextDouble()) { //prompts the user, if invalid input, to input again, until a valid value is input
System.out.println("Please input a mark between 0 and 100. ");
console.next();
}
double examscore = console.nextDouble();
if (examscore >=0 && examscore<= 100) {
System.out.println();
System.out.println("Exam Score = "+examscore);
} else {
System.out.println("Error:");
finalscore (console);
}
return examscore; //an attempt to return the VALID exam score: fails
}
}
A do-while loop would be a perfect fit. Example:
Scanner console = new Scanner(System.in);
double userInput = 0;
do {
System.out.println("Please input a mark between 0 and 100. ");
try {
userInput = console.nextDouble();
} catch (InputMismatchException e) {
System.out.println("Your input could not be interpreted as a floating-point number.");
}
} while (userInput <= 0D || userInput >= 100D);
You missed to assign result of finalscore(console) to examscore inside the else block.
if (examscore >= 0 && examscore <= 100) {
System.out.println();
System.out.println("Exam Score = " + examscore);
} else {
System.out.println("Error:");
examscore = finalscore(console);
}
You can either use a loop or a recursive call to accomplish this. I prefer a recursive call:
private static double getValidScore(Scanner console) {
System.out.println();
System.out.println("Input final exam score: ");
try {
double score = Double.parseDouble(console.nextLine());
if (score >= 0 && score <= 100) {
return score;
}
} catch (NumberFormatException nfe) {}
System.out.println("Please input a mark between 0 and 100.");
return getValidScore(console);
}
I'm a beginner in java. I want to check first if the user input is String or Double or int. If it's String, double or a minus number, the user should be prompted to enter a valid int number again. Only when the user entered a valid number should then the program jump to try. I've been thinking for hours and I come up with nothing useful.Please help, thank you!
import java.util.InputMismatchException;
import java.util.Scanner;
public class Fizz {
public static void main(String[] args) {
System.out.println("Please enter a number");
Scanner scan = new Scanner(System.in);
try {
Integer i = scan.nextInt();
if (i % 3 == 0 && (i % 5 == 0)) {
System.out.println("FizzBuzz");
} else if (i % 3 == 0) {
System.out.println("Fizz");
} else if (i % 5 == 0) {
System.out.println("Buzz");
} else {
System.out.println(i + "は3と5の倍数ではありません。");
}
} catch (InputMismatchException e) {
System.out.println("");
} finally {
scan.close();
}
}
One simple fix is to read the entire line / user input as a String.
Something like this should work. (Untested code) :
String s=null;
boolean validInput=false;
do{
s= scannerInstance.nextLine();
if(s.matches("\\d+")){// checks if input only contains digits
validInput=true;
}
else{
// invalid input
}
}while(!validInput);
You can also use Integer.parseInt and then check that integer for non negativity. You can catch NumberFormatException if the input is string or a double.
Scanner scan = new Scanner(System.in);
try {
String s = scan.nextLine();
int x = Integer.parseInt(s);
}
catch(NumberFormatException ex)
{
}
Try this one. I used some conditions to indicate the input.
Scanner scan = new Scanner(System.in);
String input = scan.nextLine();
int charCount = input.length();
boolean flag = false;
for(int x=0; x<charCount; x++){
for(int y=0; y<10; y++){
if(input.charAt(x)==Integer.toString(y))
flag = true;
else{
flag = false;
break;
}
}
}
if(flag){
if(scan.hasNextDouble())
System.out.println("Input is Double");
else
System.out.println("Input is Integer");
}
else
System.out.println("Invalid Input. Please Input a number");
Try this. It will prompt for input until an int greater than 0 is entered:
System.out.println("Please enter a number");
try (Scanner scan = new Scanner(System.in)) {
while (scan.hasNext()) {
int number;
if (scan.hasNextInt()) {
number = scan.nextInt();
} else {
System.out.println("Please enter a valid number");
scan.next();
continue;
}
if (number < 0) {
System.out.println("Please enter a number > 0");
continue;
}
//At this stage, the number is an int >= 0
System.out.println("User entered: " + number);
break;
}
}
boolean valid = false;
double n = 0;
String userInput = "";
Scanner input = new Scanner(System.in);
while(!valid){
System.out.println("Enter the number: ");
userInput = input.nextLine();
try{
n = Double.parseDouble(userInput);
valid = true;
}
catch (NumberFormatException ex){
System.out.println("Enter the valid number.");
}
}
this one just is hurting my brain. http://programmingbydoing.com/a/adding-values-in-a-loop.html
Write a program that gets several integers from the user. Sum up all the integers they give you. Stop looping when they enter a 0. Display the total at the end.
what ive got so far:
Scanner keyboard = new Scanner(System.in);
System.out.println("i will add");
System.out.print("number: ");
int guess = keyboard.nextInt();
System.out.print("number: ");
int guess2 = keyboard.nextInt();
while(guess != 0 && guess2 != 0)
{
int sum = guess + guess2;
System.out.println("the total so far is " + sum);
System.out.print("number: ");
guess = keyboard.nextInt();
System.out.print("number: ");
guess2 = keyboard.nextInt();
System.out.println("the total so far is " + sum);
}
//System.out.println("the total so far is " + (guess + guess2));
}
Declare the int sum variable outside of the while loop and only have one guess = keyboard.nextInt() inside the loop. Add the user's guess to the sum in the loop as well.
Then after the loop output the user's sum.
I.e.:
int sum;
while(guess != 0)
{
guess = keyboard.nextInt();
sum += guess;
}
System.out.println("Total: " + sum");
Edit: also remove the guess2 variable, as you will no longer need it.
The code will be as below :
public static void main(String[] args) throws Exception {
Scanner keyboard = new Scanner(System.in);
int input = 0;
int total = 0;
System.out.println("Start entering the number");
while((input=keyboard.nextInt()) != 0)
{
total = input + total;
}
System.out.println("The program exist because 0 is entered and sum is "+total);
}
Programming by Doing :)
int x = 0;
int sum = 0;
System.out.println("I will add up the numbers you give me.");
System.out.print("Number: ");
x = keyboard.nextInt();
while (x != 0) {
sum = x + sum;
System.out.println("The total so far is " + sum + ".");
System.out.print("Number: ");
x = keyboard.nextInt();
}
System.out.println("\nThe total is " + sum + ".");
import java.util.Scanner;
public class AddingInLoop {
public static void main(String[] args) {
Scanner keyboard = new Scanner(System.in);
int number, total = 0;
System.out.print("Enter a number\n> ");
number = keyboard.nextInt();
total += number;
while (number != 0) {
System.out.print("Enter another number\n> ");
number = keyboard.nextInt();
total += number;
}
System.out.println("The total is " + total + ".");
}
}
You first prompt the user to enter a number. Then you store that number into total (total += number OR total = total + number). Then, if the number entered wasn't 0, the while loop executes. Every time the user enters a nonzero number, that number is stored in total ( the value in total is getting bigger) and the while loops asks for another number. If and when a user enters 0, the while loop breaks and the program displays the value inside total. :D I myself am a beginner and had a bit of an issue with the logic before figuring it out. Happy coding!