We Keep Coding

I want to write a program that allows the user to guess a number between 0 and 100 in 7 attempts. I don't know why is this not working

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.

How can I ask the user to re-enter their choice?

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;
}

How to use methods with a while loop

I want to get the output when I enter a odd number (eg. 3) it will be give the output '3' and if I enter a even number it will print 'wrong input'.
I know I can use if else but I want to use the while loop to get it.
I am a beginner in programming so I would appreciate if someone can help me thanks
This are my codes right now. When I run it there is an error.
import java.util.Scanner;
public class UserInput {
public static void main(String[] args) {
int num;
num = readOddNum();
System.out.println("The odd integer is" + num);
}
public static int readOddNum() {
int num = 0;
Scanner sc = new Scanner(System.in);
System.out.print("Enter an odd number: ");
int num1 = sc.nextInt();
sc.close();
while ((num < 0) &&(num % 2 == 0)) {
System.out.println("Wrong input!");
}
return readOddNum();
}
}

You should change your code to
public static int readOddNum() {
Scanner sc = new Scanner(System.in);
System.out.print("Enter an odd number: ");
int num1 = sc.nextInt();
while ((num1 < 0) || (num1 % 2 == 0)) {
System.out.println("Wrong input! - try again");
num1 = sc.nextInt();
}
sc.close();
return num1;
}

Change your readOddNum logic to this..
public static int readOddNum() {
int num;
Scanner sc = new Scanner(System.in);
num = readNumber(sc);
while ((num < 0) || (num % 2 == 0)) {
System.out.println("Wrong input!");
num = readNumber(sc);
}
sc.close();
return num;
}
public static int readNumber(Scanner sc){
System.out.print("Enter an odd number: ");
return sc.nextInt();
}

The code can be rewritten in the following way
import java.util.Scanner;
public class UserInput
{
public static void main(String[] args)
{
//int num;
readOddNum();
//System.out.println("The odd integer is" + num);
}
public static void readOddNum()
{
int num = 0;
Scanner sc = new Scanner(System.in);
System.out.print("Enter an odd number: ");
int num1 = sc.nextInt();
sc.close();
while ((num1 < 0) ||(num1 % 2 == 0))
{
System.out.println("Wrong input!");
break;
}
System.out.println("The odd integer is" + num1);
// return readOddNum();
}
}
As you can see, I have directly called the method readOddNum(); and defined it as void instead of the earlier version. Also, notice the changes in the while loop. You were initialising num with 0 and using it in the while loop whereas the loop should run on num1 which is the actual user input, not num.
Next thing is you used &&(logical AND) instead of ||(logical OR) and both obviously have different meanings. && will mean that even if user enters an even number like 2 it should also be less than 0 which isn't the case. So you need to use ||. Also, you will need to use break to stop the loop once the statement is printed, else it will keep on executing infinitely as there's no other stopping condition. Remember that if else has been created for scenarios like these where you have to choose between two or more situations and execute only one, so while loop will work but it will also execute the print statement, thereby stating wrong input and odd number. This is the output you get
C:\Java\jdk1.8.0_141\bin>java UserInput
Enter an odd number: 3
The odd integer is3
C:\Java\jdk1.8.0_141\bin>java UserInput
Enter an odd number: 2
Wrong input!
The odd integer is2
Hope you understood the concept. Appreciate it, if you like it. Thank you.

Using method to find an integer repeatedly

Hello my purpose is this:
Write a method that can accept values only between 10 and 50.Sample execution:Enter a number between 10 and 50Enter a number: 5Enter a number between 10 and 50Enter a number: 12Number Entered: 12.Enter a number: 0Good ByeSo as you can see it only finishes when user enters 0.And it says different things when number is between 10 and 50 or not.I deleted again my code and started but i got stuck on some points and i gave up.My final code was:
import java.util.Scanner;
public class A{
public static void main(String[] args) {
Scanner scan = new Scanner(System.in);
System.out.println("Enter case number: ");
int caseVal = scan.nextInt();
switch(caseVal){
case 1:
System.out.println("Enter a number between 10 and 50");
System.out.println("Enter a number: ");
int num = scan.nextInt();
betweenMethod(num);
if(num == 0){
System.out.println("Good Bye");
break;
}
while(num != 0){
betweenMethod(num);
}
break;
case 2:
System.out.println("Enter a number to display its divisors: ");
int x = scan.nextInt();
System.out.println("The divisors of " + x + " are:");
divisorsMethod(x);
break;
}
scan.close();
}
public static void divisorsMethod(int a){
if(a <= 0)
System.out.println("The number should be greater than 0");
else{
for(int b = 1; b <= a; b++){
if(a % b == 0 && b != a)
System.out.print(b + ", ");
else if(b == a)
System.out.println(b);
}
}
}
public static void betweenMethod(int a){
Scanner inputscan = new Scanner(System.in);
if(a >= 10 && a <= 50){
System.out.println("Enter a number:");
a = inputscan.nextInt();
}
else if((a < 10 || a > 50) && a != 0){
System.out.println("Enter a number between 10 and 50");
System.out.println("Enter a number:");
a = inputscan.nextInt();
}
else{
System.out.println("Good Bye");
}
inputscan.close();
}
}
Sorry for uncut version.It is case 1.Every time i tried it didnt work fully.If anyone can help i would appreciate it.I'm sorry if i didnt write this question in rules.(Sorry for the grammar as well)THIS IS WHERE I AM STUCK= When i type 0 it doesnt say GoodBye and end the loop.Thats where i need help.TO EVERYONE THAT NEEDS ANSWER TOO:I figured out what to do.Basically we say while its not equal to zero right?I wrote a new method that (after last inputscan for variable)checks if the number is zero and prints good bye.So with this way it prints good bye and it goes to starting.But it cannot do anythink else because we said while not equal to 0.Anyway thats one solution.

Don't close() System.in
When you call inputscan.close() that closes the underlying InputStream, which is System.in.
Return the Value
Your method should be prompting for input between two values and returning a single value. Also, you could move your Scanner to a static (or class) field. Something like
private static Scanner inputscan = new Scanner(System.in);
public static int betweenMethod(final int a, final int b) {
int min = Math.min(a, b);
int max = Math.max(a, b);
while (true) {
System.out.printf("Please enter a number between %d and %d%n", min, max);
int in = inputscan.nextInt();
if ((in == 0) || (in >= min && in <= max)) {
return in;
}
}
}
Primitives1 are Passed-By Value
You need to assign the result of the call back to your value when you loop. Something like,
int num = betweenMethod(10, 50);
while (num != 0) {
System.out.printf("Number Entered: %d.%n", num);
num = betweenMethod(num);
}
System.out.println("Good Bye");
break;
1and Everything Else in Java.

test for data type errors in loops java

Yes, this is a homework problem. I am a beginner in programming. I am good at using if/else with for loops, since my professor asked us to while loop. I am confused.This is the question...
Q1) Suppose you are writing a game-playing program that involves 2-digit numbers, each number being composed of 2 different digits. Test if whether numbers entered in a sequence are accepted to be used in this game. Test for errors in input (including type).
My while loop to check the data type works fine at first, but after an int has been entered and I can't check the data type. Can anyone explain the problem to me please? Thank you...
public static void main(String[] args){
int num = 0;
Scanner input = new Scanner(System.in);
System.out.println("Enter a 2-digit number. The digits should be different. zero to stop");
while(!input.hasNextInt()){
System.out.println("Not an integer,try again " + num);
input.next();
}
num = input.nextInt();
while(num != 0){
while(num < 10 || num >= 99){
System.out.println("NOT good for your game! " + num );
System.out.println("Enter a 2-digit number. The digits should be different. Zero to stop");
num = input.nextInt();
}
System.out.println("Good for your game! Play! " + num);
num = input.nextInt();
}
}
}

The while loop in the first checked the System.in is entering a digit (int) or not: while(!input.hasNextInt()), but when you first input a digit, the loop exit and it enter into the next 2 loops:
while(num != 0){
while(num < 10 || num >= 99){
and then in the end of the inner loop you have:
num = input.nextInt();
This means you already assume the next input would be an int. So if you enter a non-digit input, program will throw an exception.
I would suggest you to change the whole loop into:
public static void main(String[] args) {
int num = 1;
Scanner input = new Scanner(System.in);
do {
System.out.println("Enter a 2-digit number. The digits should be different. zero to stop");
if (!input.hasNextInt()) {
System.out.println("Not an integer,try again " + num);
} else {
num = input.nextInt();
if (num < 10 || num >= 99) {
System.out.println("NOT good for your game! " + num);
} else {
System.out.println("Good for your game! Play! " + num);
}
}
} while(num != 0);
input.close();
System.out.println("game stop");
}

import java.util.Scanner;
public class Number1 {
public static void main(String[] args) {
Scanner sc = new Scanner(System.in);
String prompt = "Enter a 2-digit number. The digits should be different. Zero to stop:";
getInt(sc,prompt);
}
public static void getInt(Scanner sc,String prompt) {
System.out.println(prompt);
int num;
while (!sc.hasNextInt())
{
System.out.println("Not an integer, Try again");
sc.next();
}
num = sc.nextInt();
while(num != 0) {
if (num < 10 || num >= 99 || num == 0)
{
System.out.println("Not good for your game!");
}
else
{
System.out.println("Good for your game! Play!");
}
System.out.println(prompt);
num = sc.nextInt();
}
}
}