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NoSuchElementException error for ATM Machine app (Modified)

I am currently learning Java and I am trying to retain the information I learned by building a ATM machine app (I plan on adding more to it in the future).
My current issue is I would like to ask a user 'What would you like to do' repeatedly until a valid input is provided(current valid inputs are 'Withdraw' and 'Deposit').
I have a loop that will repeatedly ask the user 'Please select a valid choice' if the input is not valid. If the input is valid it will execute only once, ask 'What would you like to do', and then display a NoSuchElementException. Not sure how to fix this.
Here is my code:
App.java
import java.util.Scanner;
public class App {
public static void main(String[] args) throws Exception {
Scanner scanner = new Scanner(System.in);
boolean done = false;
while(!done) {
System.out.println("What woul you like to do?");
String response = scanner.next().toLowerCase();
Transactions newTransaction = new Transactions();
if (response.equals("withdraw")) {
newTransaction.Withdrawal();
} else if (response.equals("deposit")) {
newTransaction.Deposit();
} else {
System.out.println("Please select a valid choice");
}
}
scanner.close();
}
}
Transactions.java
import java.util.Scanner;
public class Transactions {
private int currentBalance = 100;
public void Withdrawal() {
Scanner scanner = new Scanner(System.in);
System.out.println("How much would you like to withdraw?");
int withdrawAmount = scanner.nextInt();
if (withdrawAmount > 0) {
if (currentBalance > 0) {
currentBalance -= withdrawAmount;
System.out.println("Amount withdrawn: $" + withdrawAmount);
System.out.println("Current Balance: $" + Balance());
if (currentBalance < 0) {
System.out.println(
"You have withdrawn more than you have in current balance.\nYou will be charged a overdraft fee");
}
} else {
System.out.println(
"You have withdrawn more than you have in current balance.\nYou will be charged a overdraft fee");
}
} else {
System.out.println("Can't remove 0 from account");
}
scanner.close();
}
public void Deposit() {
Scanner scanner = new Scanner(System.in);
System.out.println("How much would you like to deposit?");
int depositAmount = scanner.nextInt();
if (depositAmount > 0) {
currentBalance += depositAmount;
Balance();
}
System.out.println("Amount deposited: $" + depositAmount);
System.out.println("Current Balance: $" + Balance());
scanner.close();
}
public int Balance() {
return currentBalance;
}
}
Error Message
NoSuchElementException

You can use a sentinel. A sentinel is a value entered that will end the iteration.
//incomplete code showing logic
int choice;
Scanner input = new Scanner(System.in);
System.out.println("Enter Choice");
choice = input.nextInt();
while(choice != -1){ //-1 is the sentinel, can be value you choose
//Some logic you want to do
System.out.println("Enter choice or -1 to end");
choice = input.NextInt(); //notice we input choice again here
}

Like has been said you should learn about loops. There are two types while-loop and for-loop. In this case you should youse the while-loop.
The implementation of your problem could be this.
public class App {
public static void main(String[] args) throws Exception {
Scanner scanner = new Scanner(System.in);
System.out.println("What woul you like to do?");
String response;
Transactions newTransaction = new Transactions();
while (true) {
response = scanner.next().toLowerCase();
if (response.equals("withdraw")) {
newTransaction.Withdrawal();
break;
} else if (response.equals("deposit")) {
newTransaction.Deposit();
break;
} else {
System.out.println("Please select a valid choice");
}
}
scanner.close();
}
}

How do I validate user input in Java

I wrote a bmi calculator program and I want to validate user input so that the user would not enter a negative number for the height or weight input.
How do I do this? I am new to Java, so I have no idea.
import java.util.Scanner;
public class BMICalculator {
public static void main(String[] args) throws Exception {
calculateBMI();
}
private static void calculateBMI() throws Exception {
System.out.print("Please enter your weight in kg: ");
Scanner s = new Scanner(System.in);
float weight = s.nextFloat();
System.out.print("Please enter your height in cm: ");
float height = s.nextFloat();
float bmi = (100*100*weight)/(height*height);
System.out.println("Your BMI is: "+bmi);
printBMICategory(bmi);
s.close();
}
private static void printBMICategory(float bmi) {
if(bmi < 24) {
System.out.println("You are underweight");
}else if (bmi < 29) {
System.out.println("You are healthy");
}else if (bmi < 34) {
System.out.println("You are overweight");
}else {
System.out.println("You are OBESE");
}
}
}

you can keep asking for value until the user input a valid number
private float readZeroOrPositiveFloat(Scanner scanner , String promptMessage)
{
float value = -1;
while(value < 0){
System.out.println(promptMessage);
value = scanner.nextFloat();
}
return value;
}
private static void calculateBMI() throws Exception {
System.out.print("Please enter your weight in kg: ");
Scanner s = new Scanner(System.in);
float weight = readZeroOrPositiveFloat(s , "Please enter your weight in kg: ");
float height = readZeroOrPositiveFloat(s , "Please enter your height in cm: ");
float bmi = (100*100*weight)/(height*height);
System.out.println("Your BMI is: "+bmi);
printBMICategory(bmi);
s.close();
}

Just to handle negative inputs and keep asking for valid input,
boolean flag = true;
while(flag){
System.out.print("Please enter your weight in kg: ");
int weight = sc.nextInt();
System.out.print("Please enter your height in cm: ");
int height = sc.nextInt();
if(weight >= 0 && height >= 0){
float bmi = (100*100*weight)/(height*height);
flag = false;
}else{
System.out.println("Invalid Input");
}
}
To handle all the unexpected inputs and keep asking for valid input,
boolean flag = true;
while(flag){
Scanner sc = new Scanner(System.in);
try{
System.out.print("Please enter your weight in kg: ");
int weight = sc.nextInt();
System.out.print("Please enter your height in cm: ");
int height = sc.nextInt();
if(weight >= 0 && height >= 0){
float bmi = (100*100*weight)/(height*height);
flag = false;
}else{
System.out.println("Invalid Input");
}
}catch(Exception e){
System.out.println("Invalid Input");
}
}

When you get input from the scanner, you could use an if statement to make sure the value is not negative. For example:
if(input value <= 0){
System.out.println("Invalid Input");
}else { *program continues* }

Is it possible to return a user-input declared double within an if statement for use in the main?

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);
}

if a user inputs a letter instead of a number tell them it's not a number

I'm making a guessing game, all the code works fine except for that I want them to make a number to guess between, I can't seem to figure out how to make it so that if the user inputs a letter like "d" instead of a number like "15" it will tell them they can't do that.
Code:
import java.util.Scanner;
import java.util.Random;
public class GuessingGame {
public static void main(String[] args) {
Scanner input = new Scanner(System.in);
Random rand = new Random();
while (true) {
System.out.print("Pick a number: ");
int number = input.nextInt();
if (number != int) {
System.out.println("That's not a number");
} else if (number == int) {
int random = rand.nextInt(number);
break;
}
}
System.out.println("You have 5 attempts to guess the number or else you fail. Goodluck!");
System.out.println("");
System.out.println("Type 'begin' to Begin!");
System.out.print("");
String start = input.next();
if (start.equals("begin")) {
System.out.print('\f');
for(int i=1; i<6; i++) {
System.out.print("Enter a number between 1-" + number + ": ");
int number = input.nextInt();
if (number > random) {
System.out.println("Too Big");
System.out.println("");
} else if (number < random) {
System.out.println("Too Small");
System.out.println("");
} else if (number == random) {
System.out.print('\f');
System.out.println("Correct!");
break;
}
if (i == 5) {
System.out.print('\f');
System.out.println("You have failed");
System.out.println("Number Was: " + random);
}
}
} else if (start != "begin") {
System.out.print('\f');
System.out.println("Incorrect Command");
System.out.println("Please Exit Console And Retry");
}
}
}

use try catch
for example
try{
int a=sc.nextInt();
}catch(Exception e){
System.out.println("not an integer");
}

You could use nextLine() instead of nextInt() and check the out coming String if it matches() the regular expression [1-9][0-9]* and then parse the line with Integer.valueOf(str).
Like:
String str=input.nextLine();
int i=0;
if(str.matches("[1-9][0-9]*"){
i=Integer.valueOf(str);
} else {
System.out.println("This is not allowed!");
}
I hope it helps.

Do something like this:
Scanner scan = new Scanner(System.in);
while(!scan.hasNextInt()) { //repeat until a number is entered.
scan.next();
System.out.println("Enter number"); //Tell it's not a number.
}
int input = scan.nextInt(); //Get your number here

How to check if user input is String, double or long in Java

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.");
}
}