I know how to display an Error message if the user enters a number below 10 or higher than 999 but how can I code to make sure the program doesn't end after the users enter a number below 10 or higher than 999 and give them a second chance to enter their valid input over and over again until they give a correct input.
import java.util.Scanner;
public class Ex1{
public static void main(String args[]){
java.util.Scanner input = new java.util.Scanner(System.in);
System.out.print("Enter an integer between 10 and 999: ");
int number = input.nextInt();
int lastDigit = number % 10;
int remainingNumber = number / 10;
int secondLastDigit = remainingNumber % 10;
remainingNumber = remainingNumber / 10;
int thirdLastDigit = remainingNumber % 10;
int sum = lastDigit + secondLastDigit + thirdLastDigit;
if(number<10 || number>999){
System.out.println("Error!: ");
}else{
System.out.println("The sum of all digits in " +number + " is " + sum);
}
}
}
You will need to use a loop, which basically, well, loops around your code until a certain condition is met.
A simple way to do this is with a do/while loop. For the example below, I will use what's called an "infinite loop." That is, it will continue to loop forever unless something breaks it up.
import java.util.Scanner;
class Main {
public static void main(String[] args) {
Scanner scanner = new Scanner(System.in);
int num;
// Start a loop that will continue until the user enters a number between 1 and 10
while (true) {
System.out.println("Please enter a number between 1 - 10:");
num = scanner.nextInt();
if (num < 1 || num > 10) {
System.out.println("Error: Number is not between 1 and 10!\n");
} else {
// Exit the while loop, since we have a valid number
break;
}
}
System.out.println("Number entered is " + num);
}
}
Another method, as suggested by MadProgrammer, is to use a do/while loop. For this example, I've also added some validation to ensure the user enters a valid integer, thus avoiding some Exceptions:
import java.util.Scanner;
class Main {
public static void main(String[] args) {
Scanner scanner = new Scanner(System.in);
int num;
// Start the loop
do {
System.out.println("Please enter a number between 1 - 10:");
try {
// Attempt to capture the integer entered by the user. If the entry was not numeric, show
// an appropriate error message.
num = Integer.parseInt(scanner.nextLine());
} catch (NumberFormatException e) {
System.out.println("Error: Please enter only numeric characters!");
num = -1;
// Skip the rest of the loop and return to the beginning
continue;
}
// We have a valid integer input; let's make sure it's within the range we wanted.
if (num < 1 || num > 10) {
System.out.println("Error: Number is not between 1 and 10!\n");
}
// Keep repeating this code until the user enters a number between 1 and 10
} while (num < 1 || num > 10);
System.out.println("Number entered is " + num);
}
}
Try this, i just include the while loop in your code it will work fine.
public static void main(String[] args) {
Scanner input = new Scanner(System.in);
int number = askInput(input);
while(number<10 || number>999) {
System.out.println("Sorry Try again !");
number = askInput(input);
}
int lastDigit = number % 10;
int remainingNumber = number / 10;
int secondLastDigit = remainingNumber % 10;
remainingNumber = remainingNumber / 10;
int thirdLastDigit = remainingNumber % 10;
int sum = lastDigit + secondLastDigit + thirdLastDigit;
if(number<10 || number>999){
System.out.println("Error!: ");
}else{
System.out.println("The sum of all digits in " +number + " is " + sum);
}
}
private static int askInput(Scanner input) {
int number = input.nextInt();
return number;
}
Related
public class Main {
public static void main(String[] args) {
Scanner scan = new Scanner(System.in);
int rnd = (int)(Math.random() * 101);
System.out.println("The program is going to give a number that is between 0 and 100 (including them). You can guess it by pressing Run.");
System.out.println("Enter your number:");
int num = scan.nextInt();
for (int count = 1; count <= 7; count++) {
while (num != rnd) {
if (num < rnd) {
System.out.println("Your guess is too low.");
}
if (num > rnd) {
System.out.println("Your guess is too high.");
}
if ((Math.abs(rnd - num) == 1) || (Math.abs(rnd - num) == 2)) {
System.out.println("But your guess is VERY close.");
}
num = scan.nextInt();
}
System.out.println("You got it right!");
}
System.out.println("You should guess it in 7 tries.");
}
}
So I used two loops and just nested them. Is that how it works for this? Right now the code is like starting with for loop and if that is true it goes to the while loop part where the guessing number takes place. Can this be fixed with just moving some codes and fixing minor areas around?
What you should do in a situation like this is do the code manually. Literally. Grab a piece of paper and pretend you're a computer. It's a good exercise, and it will help you figure out your problem.
The problem is your inner loop. It loops until they guess correctly regardless of the number of attempts. Then you force them to do it 6 more times with the outer loop.
You really only need 1 loop. I would have a single loop like this:
int attempts = 0;
int num = 0;
do {
num = scan.nextInt();
... most of the if code from your inner loop but not another scan.nextInt
} while (++attempts < 7 && num != rnd);
// and here you look at num == rnd to see if success or failures
I think you should rebuild you code to make it more clear.
Split the title (with description of the task)
Split main loop where you read user input and check it with expected number
Split output of the final result, where you print the result.
public static void main(String[] args) {
Scanner scan = new Scanner(System.in);
final int rnd = new Random().nextInt(101);
final int maxAttempts = 7;
System.out.println("The program is going to give a number that is between 0 and 100 (including them).");
System.out.println("You can guess it within maximum " + maxAttempts + " attempts by pressing Run.");
boolean success = false;
for (int attempt = 1; attempt <= maxAttempts && !success; attempt++) {
System.out.format("(%s of %s) Enter your number: ", attempt, maxAttempts);
int num = scan.nextInt();
if (num == rnd)
success = true;
else {
System.out.print("Your guess is too " + (num > rnd ? "high" : "low") + '.');
System.out.println(Math.abs(rnd - num) <= 2 ? " But it's VERY close." : "");
}
}
System.out.println(success ? "You got it right!" : "Bad luck this time. Buy.");
}
import java.util.Scanner;
class Main {
public static void main(String[] args)
{
Scanner scan = new Scanner(System.in);
int rnd = (int) (Math.random() * 101);
System.out.println("The program is going to give a number that is between 0 and 100 (including them). You can guess it by pressing Run.");
System.out.println("Enter your number:");
int num = scan.nextInt();
for(int count = 1; count <= 7; count++)
{
if (num < rnd)
{
System.out.println("Your guess is too low.");
}
else if (num > rnd)
{
System.out.println("Your guess is too high.");
}
else if ((Math.abs(rnd - num) == 1) || (Math.abs(rnd - num) == 2))
{
System.out.println("But your guess is VERY close.");
}
else
System.out.println("You got it right!");
System.out.println("Enter Next number: ");
num = scan.nextInt();
}
}
}
It should work Fine.Basically Your reasoning wass wrong because You are putting a while loop inside a for loop. What you want to do is you want only 7 iteration.In those 7 iterations you are checking the conditions based on user Input.
I am trying to make a Guessing Game for a Java assignment, I have everything I need except exception handling, you see I'm trying to make it display an error message instead of displaying Exception in thread "main" java.util.InputMismatchException when someone tries to enter a numerical number in alphabetical form. The code I have is followed.
(I know I need a try and catch but I don't know what to put exactly.)
package guessNumber;
import java.util.Scanner;
public class GuessNumberApp {
public static void main(String[] args) {
final int LIMIT = 10;
System.out.println("Guess the number!");
System.out.println("I'm thinking of a number from 1 to " + LIMIT);
System.out.println();
// get a random number between 1 and the limit
double d = Math.random() * LIMIT; // d is >= 0.0 and < limit
int number = (int) d; // convert double to int
number++; // int is >= 1 and <= limit
// prepare to read input from the user
Scanner sc = new Scanner(System.in);
int count = 1;
while (true) {
int guess = sc.nextInt();
System.out.println("You guessed: " + guess);
if (guess < 1 || guess > LIMIT) {
System.out.println("Your Guess is Invalid.");
continue;
}
if (guess < number) {
System.out.println("Too Low.");
} else if (guess > number) {
System.out.println("Too High.");
} else {
System.out.println("You guessed it in " + count + " tries.\n");
break;
}
count++;
}
System.out.println("Bye!");
}
}
try something like that:
try {
int guess = sc.nextInt();
} catch(InputMismatchException e) {
System.out.println("some nice error message");
continue;
}
This would replace
int guess = sc.nextInt();
I put the code in a do-while loop. It asks the user which menu option they want and it computes the equation for them. The code is supposed to keep on going until the user hits 4 which is the quit option, but it stops after one sequence. I dont know what I need to change or add so it keeps on going.
import java.util.Scanner;
import java.text.DecimalFormat;
class Lab5
{
public static void main(String[] args) //header of the main method
{
Scanner in = new Scanner(System.in);
int choice;
int rem = 0;
int num;
do
{
//user prompt
System.out.print("Choose from the following menu\n1) Calculate the sum of integers 1 to m\n2) Factorial of a number\n3) Repeat the first number\n4) Quit\n:");
choice = in.nextInt();
switch(choice)
{
case 1:
int m, sum =0;
int i = 1;
System.out.print("Enter the number:");
m = in.nextInt();
while (i <= m)
{
sum=sum+i;
i++;
}
System.out.print("The sum of:" + m + ' ' + "is" + ' ' + sum);
break;
case 2:
int number, fact =1;
System.out.print("Enter the number:");
number = in.nextInt();
i=1;
for (int factor = 2; factor <= number; factor++)
{
fact = fact*factor;
}
System.out.print("The Factorial of +:" + number + ' ' + "is" + ' ' + fact);
break;
case 3:
System.out.print("Enter the number:");
num = in.nextInt();
while(num!=0)
{
rem = num%10;
num = num/10;
}
System.out.print("The leftmost digit is:" + rem);
break;
default:
break;
}
} while (choice == '4');
System.out.print(" ");
}
}
You wrote this as do ... while ( choice == '4' ), which means it will only continue if the user enters a 4.
Sounds like you want choice != '4'.
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
Hi I am trying to take in an integer between 1 and 10.
If the user does not do so would like the program to run again.
I believe that I need to use an else if statement that calls on my function but I do not know how to call functions in java.
Here is my code so far:
import java.util.Scanner;
public class NumChecker {
public static void main(String[] args){
Scanner in = new Scanner(System.in);
System.out.print("Enter a number between 1 and 10: ");
int num1 = in.nextInt();
if (num1 >= 1 && num1 <= 10); {
System.out.println("Input = " + num1);
}
else if {
???
}
}
}
if-else always work.
You made a mistake in the if statement.
there is no ; for an if
if (num1 >= 1 && num1 <= 10) {//no semicolon
System.out.println("Input = " + num1);
}
else if(num < 0) {//should have a condition
...
}
else
{
...
}
What happens if I put a semicolon at the end of an if statement?.
How do I ask the user again if the input is not in between 1 and 10?
Loop until you get what you want :)
Scanner sc = new Scanner(System.in);
int num = 0;
while(true)
{
num = sc.nextInt();
if(num > 0 && num < 11)
break;
System.out.println("Enter a number between 1 and 10");
}
System.out.println(num);
Since you are expecting a number between 1 to 10, but you don't know how many numbers you will get until you get a valid number, I'd suggest to use a while loop, like so:
import java.util.Scanner;
public class NumChecker {
public static void main(String[] args){
Scanner in = new Scanner(System.in);
System.out.print("Enter a number between 1 and 10: ");
int num1 = in.nextInt();
while (num1 < 1 || num1 > 10) {
System.out.print("Invalid number, enter another one: ");
num1 = in.nextInt();
}
System.out.println("Input = " + num1);
}
}