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Java checking if input is a double or character

I'm writing a program in Java that does temperature conversion, but running into an issue.
import java.util.*;
public class TempCon2 {
public static void main (String[] args) {
double f,c,temp;
char ch,op;
Scanner sc = new Scanner(System.in);
System.out.println("This program converts temperatures from Fahrenheit to Celsius and vica versa.");
do {
System.out.print("Please enter your temperature: ");
temp = sc.nextDouble();
System.out.print("Please enter the units (F/C): ");
ch = sc.next().charAt(0);
if(ch=='F') {
c=(temp-32)*5/9;
System.out.println("\nThe temperature of " + temp + " degrees Fahrenheit is equivalent to " + c + " degrees Celsius!"); }
else if(ch=='C') {
f=(temp*9/5)+32;
System.out.println("\n The temperature of " + temp + " degrees Celsius is equivalent to " + f + " degrees Fahrenheit!"); }
System.out.print("Do you wish to do another conversion? (Y/N): ");
op=sc.next().charAt(0);
System.out.println();
if(op=='N' || op=='n') {
break; }
}while((op=='Y' || op=='y'));
System.out.println("Thank you, Goodbye");
}
}
I want to be able to check when the user inputs their temperature if its a number, and if not it returns a message that says " 'user input' is not a number. Please enter a number". As well as when it asks for the units that if you enter anything other than "F" or "C" it does the same as the number one.

You can try by parsing the String value to Double:
Double temp;
try {
temp = Double.parseDouble(sc.nextLine());
} catch (NumberFormatException nfe){
System.out.println("The input is not a number");
break;
}
From Double.parseDouble doc:
NumberFormatException – if the string does not contain a parsable
double.

What you want is 'complex', in the sense that you don't hunt for a single method that does this; there is no scanner.askForCorFAndKeepAskingIfTheyEnterSomethingElse();.
So, you do the same thing you always do when faced with a task you want to do repeatedly which isn't trivial: You make a method.
public static char askTemperatureUnit(Scanner s) {
...
}
public static double askTemperatureAmount(Scanner s) {
...
}
These methods will use a few aspects:
a while (true) loop. If the result is what you wanted, return it. (which also ends the loop by returning out of it). Otherwise, you tell the user they didn't enter what you wanted and let it loop.
A way to respond when the user fails to enter a double value:
while (true) {
try {
return scanner.nextDouble();
} catch (InputMismatchException e) {
scanner.next(); // eat the invalid input away
System.out.println("Hey now enter a number please!");
}
}
You can also call scanner.next() and then use try/catch to run Double.parseDouble - same end result, whatever you feel is best.
While you're at it, c = Character.toUpperCase(c) lets you turn an n into an N which is nice.

You need a couple of more do-while loops the way you have put for prompting the user if they want to continue.
I also recommend you use Scanner::nextLine to avoid the problems mentioned in this thread.
public class Main {
public static void main(String[] args) {
double f, c, temp;
char ch, op;
Scanner sc = new Scanner(System.in);
System.out.println("This program converts temperatures from Fahrenheit to Celsius and vica versa.");
do {
boolean valid;
do {
valid = true;
System.out.print("Please enter your temperature: ");
try {
temp = Double.parseDouble(sc.nextLine());
do {
valid = true;
System.out.print("Please enter the units (F/C): ");
ch = sc.nextLine().charAt(0);
if (ch == 'F') {
c = (temp - 32) * 5 / 9;
System.out.println(
"\nThe temperature of " + temp + " degrees Fahrenheit is equivalent to " + c
+ " degrees Celsius!");
} else if (ch == 'C') {
f = (temp * 9 / 5) + 32;
System.out
.println("\n The temperature of " + temp + " degrees Celsius is equivalent to " + f
+ " degrees Fahrenheit!");
} else {
System.out.println("Invalid input. Enter F or C");
valid = false;
}
} while (!valid);
} catch (NumberFormatException e) {
System.out.println("Invalid input. Enter a number only");
valid = false;
}
} while (!valid);
System.out.print("Do you wish to do another conversion? (Y/N): ");
op = sc.nextLine().charAt(0);
System.out.println();
if (op == 'N' || op == 'n') {
break;
}
} while ((op == 'Y' || op == 'y'));
System.out.println("Thank you, Goodbye");
}
}
A sample run:
This program converts temperatures from Fahrenheit to Celsius and vica versa.
Please enter your temperature: abc
Invalid input. Enter a number only
Please enter your temperature: 12.5
Please enter the units (F/C): X
Invalid input. Enter F or C
Please enter the units (F/C): F
The temperature of 12.5 degrees Fahrenheit is equivalent to -10.833333333333334 degrees Celsius!
Do you wish to do another conversion? (Y/N): y
Please enter your temperature: xyz
Invalid input. Enter a number only
Please enter your temperature: pqr
Invalid input. Enter a number only
Please enter your temperature: -40
Please enter the units (F/C): a
Invalid input. Enter F or C
Please enter the units (F/C): F
The temperature of -40.0 degrees Fahrenheit is equivalent to -40.0 degrees Celsius!
Do you wish to do another conversion? (Y/N): n
Thank you, Goodbye

Illegal start of expression on my function public static void

My code is about looping and method, A program that will let user either compute an area or use the 4 basic math operations. the (Triangle, Square,Rectangle) with their choice of process: Addition, Subtraction, Multiplication and Division.
I think i properly closed the addition function there and i already check the closing every functions they seem work well other than the addtion function since thats the only error i got.
import java.util.Scanner;
public class Main{
public static void main(String[] args) {
Scanner scan = new Scanner(System.in);
//WHILE LOOP FOR CHOICES
while(true){//CHOICES LOOP
System.out.println("∘₊✧─────────────────────────────────────✧₊∘");
System.out.println("Input Choice of Process");
System.out.println("1 - Addition process");
System.out.println("2 - Subtraction process");
System.out.println("3 - Multiplication process");
System.out.println("4 - Division process");
System.out.println("5 - Compute process");
System.out.println("Your choice: ");
int option = scan.nextInt();
System.out.println("∘₊✧─────────────────────────────────────✧₊∘");
if(option == 1){
Add();
}
else if(option == 2){
Sub();
}
else if(option == 3){
Mul();
}
else if(option == 4){
Div();
}
else if(option == 5){
Com();
}
else if((option>=6)&&(option<=100)){//INVALID
System.out.println("Invalid Input, Please Input Choice Again.");
}
else{//- if user input other number, the program will break and stop from looping
break;
}
Here Im getting a error here im not sure what is it
public static void Add(){
System.out.println("ADDITION");
System.out.println("Enter two numbers: ");
System.out.println("1st number: ");
int add1=scan.nextInt();
System.out.println("2nd number: ");
int add2=scan.nextInt();
int addtotal=add1+add2;
if(addtotal>100){// In addition, if the sum is higher than 100, print the answer the word high. if equal and below 100, print low
System.out.println("Total is "+addtotal+" High");
}
else if(addtotal<100){
System.out.println("Total is "+addtotal+" Low");
}
}
public static void Sub(){//SUBTRACTION
System.out.println("SUBTRACTION");
System.out.println("Enter two numbers: ");
System.out.println("1st number: ");
int sub1=scan.nextInt();
System.out.println("2nd number: ");
int sub2=scan.nextInt();
int subtotal=sub1-sub2;
if(subtotal<0){// In subtraction, if the difference is negative, print invalid. If 0 or above, print the difference and the word valid.
System.out.println("Invalid ");
}
else if(subtotal>0){
System.out.println("Total is "+subtotal+" Valid");
}
}
public static void Mul(){//MULTIPLICATION
System.out.println("MULTIPLICATION");
System.out.println("Enter two numbers: ");
System.out.println("1st number: ");
double multi1=scan.nextDouble();//In multiplication, make it accepts decimal value
System.out.println("2nd number: ");
double multi2=scan.nextDouble();
double multitotal=multi1*multi2;
System.out.println("Total is "+multitotal);
}
public static void Div(){
System.out.println("DIVISION");
System.out.println("Enter two numbers: ");
System.out.println("1st number: ");
int div1=scan.nextInt();
System.out.println("2nd number: ");
int div2=scan.nextInt();
int divtotal= div1 / div2;
int divremainder= div1 % div2;//In division, if it has remainder, print the answer and the remainder.
System.out.println("Total is "+divtotal);
System.out.println("Remainder is "+divremainder);
}
public static void Com(){// If user choose 5, the user needs to choose again on a ,b or c. If other letter, print invalid and then go pack on choosing of process.
System.out.println("∘₊✧─────────────────────────────────────✧₊∘");
System.out.println("Input Choice of Process");
System.out.println("a - Rectangle");
System.out.println("b - Square");
System.out.println("c - Triangle");
System.out.println("Your choice: ");
Scanner Keyboard = new Scanner(System.in);
Scanner input = new Scanner(System.in);
char choice = Keyboard.nextLine().charAt(0);
System.out.println("∘₊✧─────────────────────────────────────✧₊∘");
if (choice == 'A' || choice == 'a')//rectangle
{
System.out.println("Enter length of rectangle's base: ");
double base = input.nextDouble();
System.out.println("Enter length of rectangle's height: ");
double height = input.nextDouble();
double rArea = base * height;
System.out.println("The area of a rectangle with a base length of " + base + " and a height of " + height + " is " + rArea + ".");
}
else if (choice == 'B' || choice == 'b') //square
{
System.out.println("Enter length of square's sides: ");
double sSide = input.nextDouble();
double sArea = sSide * sSide;
System.out.println("The area of a square with a side length of " + sSide + " is " + sArea + ".");
}
else if (choice == 'C' || choice == 'c') //traingle
{
System.out.println("Enter traingle's side length: ");
double tSide = input.nextDouble();
double tArea = tSide * tSide * tSide;
System.out.println("The area of a triangle with a side length of " + tSide + " is " + tArea + ".");
}
else //invalid
{
System.out.println("You've entered an invalid character.");
}
}
}

You haven't got a closing brace for your main method

Trying to have program return to main menu after user answers yes to continue or have program end and display message of total if user answers no

public static void main(String[] args) {
Scanner input = new Scanner(System.in);
boolean start = true;
while(start)
System.out.printf("%70s %n", " ##### Zoos Australia ##### " + "\n");
System.out.printf("%57s %n", "Main Menu" + "\n");
System.out.printf("%72s %n", "Zoo has the following ticketing options:");
System.out.print("\n");
System.out.printf("%59s %n", "1 = Child (4-5 yrs)");
System.out.printf("%59s %n", "2 = Adult (18+ yrs)");
System.out.printf("%60s %n", "3 = Senior (60+ yrs)");
System.out.println("\n");
String choose1 = "";
String choose2 = "";
String choose3 = "";
String selected = "";
int option = 0;
{
System.out.print("Please select an option: ");
option = input.nextInt();
if (option == 1) {
choose1 = "Child";
selected = choose1;
} else if (option == 2) {
choose2 = "Adult";
selected = choose2;
} else if (option == 3) {
choose3 = "Senior";
selected = choose3;
}
}
// done
System.out.println("\n");
int price = 0;
int tickets = 0;
System.out.print("Enter the number of tickets: ");
tickets = input.nextInt();
if (selected == choose1) {
price = 10;
} else if (selected == choose2) {
price = 20;
} else if (selected == choose3) {
price = 15;
}
System.out.println("\n");
System.out.print("You are purchasing " + tickets + " " + selected + " tickets at " + "$" + price + " each!");
System.out.println("\n");
int confirm = 0;
System.out.print("Press 1 to confirm purchase: ");
confirm = input.nextInt();
if (confirm != 1) {
System.out.print("Incorrect Key. Please return to Main Menu");
System.out.println("\n");
} else {
break;
}
System.out.println("\n");
int total = tickets;
price = total * price;
System.out.print("Total amount for " + selected + " tickets: " + "$" + price);
System.out.println("\n");
String pick = "";
System.out.print("Do you wish to continue: ");
input.next();
System.out.println("\n");
if (pick == "no") {
System.out.print("Total amount payable is: " + "$" + price);
System.out.println("\n");
System.out.print("Have a nice day!");
System.out.println("\n");
}}}
Trying to do this at the end of the program where user is asked "Do you wish to continue" using a method or something but cant get it to work. Either the program returns to main menu only or the program ends and displays the total message "Total amount payable..." etc. I have tried using while with continue and break. Using boolean with true and false. But no luck. Thank you anyone that may be able to clear this up for me please.

First, you have to assign the users's input to a variable: pick = input.next(). After that, the problem is that you compare the user's input string with a "no" string by using == operator. When comparing reference types (objects) (and String is an object), in most cases == operator gives you an unpredictable result, because it compares the reference (address of an object in memory) and not the actual content. Please remember, that you always have to use the .equals() method instead. You also have to break from your loop, when the user's input is "no".
There is plenty of material concerning this issue. You can check, for instance, this one How do I compare strings in Java?
P.S. I quickly looked at the rest of your code and put some additional comments, which might help you to improve it. Good luck with learning Java!
Scanner input = new Scanner(System.in);
// boolean start = true; you don't need this line
while(true) { // 'true' condition makes it an infinite loop until you use break
// You also have to surround your while loop with curly braces,
// otherwise you fall into an infinite loop
System.out.printf("%70s %n", " ##### Zoos Australia ##### \n");
System.out.printf("%57s %n", "Main Menu\n");
System.out.printf("%72s %n", "Zoo has the following ticketing options: \n");
System.out.printf("%59s %n", "1 = Child (4-5 yrs)");
System.out.printf("%59s %n", "2 = Adult (18+ yrs)");
System.out.printf("%60s %n", "3 = Senior (60+ yrs)\n");
String choose1 = "";
String choose2 = "";
String choose3 = "";
String selected = "";
int option = 0;
System.out.print("Please select an option: ");
option = input.nextInt();
if (option == 1) {
choose1 = "Child";
selected = choose1;
} else if (option == 2) {
choose2 = "Adult";
selected = choose2;
} else if (option == 3) {
choose3 = "Senior";
selected = choose3;
}
System.out.println(); // "\n" is a redundant argument
int price = 0;
int tickets = 0;
System.out.print("Enter the number of tickets: ");
tickets = input.nextInt();
if (selected.equals(choose1)) { // you should never compare strings with == operator! Always use .equals() instead
price = 10;
} else if (selected.equals(choose2)) {
price = 20;
} else if (selected.equals(choose3)) {
price = 15;
}
System.out.println();
System.out.print("You are purchasing " + tickets + " " + selected + " tickets at " + "$" + price + " each!");
System.out.println();
int confirm = 0;
System.out.print("Press 1 to confirm purchase: ");
confirm = input.nextInt();
if (confirm != 1) {
System.out.print("Incorrect Key. Please return to Main Menu");
System.out.println("\n");
} else {
//break; you cannot use 'break' in the if statement! You have to figure out another way, how to handle an invalid input
}
System.out.println();
int total = tickets;
price = total * price;
System.out.print("Total amount for " + selected + " tickets: " + "$" + price);
System.out.println();
String pick = "";
System.out.print("Do you wish to continue: ");
pick = input.next(); // you have to assign the input to a variable
System.out.println();
if (pick.equals("no")) { // You have to ALWAYS use .equals() when comparing Strings or any other reference types! == works correctly only with primitive types
System.out.print("Total amount payable is: " + "$" + price);
System.out.println();
System.out.print("Have a nice day!");
System.out.println();
break; // you need to break from the loop in the end
}
}
}

Do/while loop not returning to the top?

recently started computer programming and I am stuck on a homework assignment. I created a loop but instead of going back to the top, it starts 1 step ahead of where I intended it to. (it's all listed in the comments I made in the coding. I have been trying to figure this out for the past 6 hours so it would greatly appreciated if someone can help me.
import java.util.Scanner;
import java.text.DecimalFormat;
public class Election
{
public static void main (String[] args)
{
DecimalFormat f = new DecimalFormat("##.00");
DecimalFormat n = new DecimalFormat("##");
float votesForPolly;
float votesForErnest;
float totalPolly = 0;
float totalErnest = 0;
String response;
int precinctsforpolly = 0;
int precinctsforernest = 0;
int precinctsties = 0;
Scanner scan = new Scanner(System.in);
System.out.println ();
System.out.println ("Election Day Vote Counting Program");
System.out.println ();
do
{
//point A
System.out.println("Do you wish to enter more votes? Enter y:n");
response = scan.next();
if (response.equals("y"))
{
//point B
System.out.println("Enter votes for Polly:");
votesForPolly = scan.nextInt();
System.out.println("Enter votes for Ernest:");
votesForErnest = scan.nextInt();
totalPolly = totalPolly + votesForPolly;
totalErnest = totalErnest + votesForErnest;
System.out.println("Do you wish to add precincts? Enter y:n");
response = scan.next();
while (response.equals("y"))
{
System.out.println("How many precincts voted for Polly: ");
precinctsforpolly = scan.nextInt();
System.out.println("How many precincts votes for Ernest: ");
precinctsforernest = scan.nextInt();
System.out.println("How many were ties: ");
precinctsties = scan.nextInt();
break;
//not returning to point A, instead it returns to point B
}
if (response.equals("n"))
{
break;
}
if (response.equals("n"))
{
break;
}
}
}
while (response.equals("n"));
System.out.println("Final Tally");
System.out.println("Polly received:\t " + n.format(totalPolly) + " votes\t" + f.format((totalPolly/(totalPolly + totalErnest))*100) + "%\t" + precinctsforpolly + " precincts");
System.out.println("Ernest received: " + n.format(totalErnest) + " votes\t" + f.format((totalErnest/(totalPolly + totalErnest))*100) + "%\t" + precinctsforernest + " precincts");
System.out.println("\t\t\t\t\t" + precinctsties + " precincts tied");
}
}
My guess is that the string response has already been determine to be y at the end of the loop which is why it skips the first step and jumps right back into the loop assuming my answer is already y.

You will just need to strip your code of unnecessary breaks and also handle the 2 responses differently. Your loop should also continue when the response is y, not the other way round.
See edited code below:
import java.util.Scanner;
import java.text.DecimalFormat;
public class Election
{
public static void main (String[] args)
{
DecimalFormat f = new DecimalFormat("##.00");
DecimalFormat n = new DecimalFormat("##");
float votesForPolly;
float votesForErnest;
float totalPolly = 0;
float totalErnest = 0;
String response;
int precinctsforpolly = 0;
int precinctsforernest = 0;
int precinctsties = 0;
Scanner scan = new Scanner(System.in);
System.out.println ();
System.out.println ("Election Day Vote Counting Program");
System.out.println ();
do
{
//point A
System.out.println("Do you wish to enter more votes? Enter y:n");
response = scan.next();
if (response.equals("y"))
{
//point B
System.out.println("Enter votes for Polly:");
votesForPolly = scan.nextInt();
System.out.println("Enter votes for Ernest:");
votesForErnest = scan.nextInt();
totalPolly = totalPolly + votesForPolly;
totalErnest = totalErnest + votesForErnest;
System.out.println("Do you wish to add precincts? Enter y:n");
String response2 = scan.next();//create a new response variable, so the loop doesn't confuse which response to break on
//I removed the inner loop. If you really intended for this to be an inner loop then the while(response2.equals("y")){} should be around the question, not after
if (response2.equals("y"))
{
System.out.println("How many precincts voted for Polly: ");
precinctsforpolly = scan.nextInt();
System.out.println("How many precincts votes for Ernest: ");
precinctsforernest = scan.nextInt();
System.out.println("How many were ties: ");
precinctsties = scan.nextInt();
}
//removed the unnecessary checks for when response in 'n'
}
}
while (response.equals("y"));
System.out.println("Final Tally");
System.out.println("Polly received:\t " + n.format(totalPolly) + " votes\t" + f.format((totalPolly/(totalPolly + totalErnest))*100) + "%\t" + precinctsforpolly + " precincts");
System.out.println("Ernest received: " + n.format(totalErnest) + " votes\t" + f.format((totalErnest/(totalPolly + totalErnest))*100) + "%\t" + precinctsforernest + " precincts");
System.out.println("\t\t\t\t\t" + precinctsties + " precincts tied");
}
}

if (response.equals("n"))
{
break;
}
breaks your while loop.
You might want to loop again if user's response if 'y'.
In that case, use while (response.equals("y"));

Your requirement is to break out if the user enters "n" but loop while the user input is "y", but your code says,
do{
.....
}while (response.equals("n"));
It should be,
while (response.equals("y"));

do {
//point A
System.out.println("Do you wish to enter more votes? Enter y:n");
response = scan.next();
if (response.equals("y"))
{
//point B
#code
if (response.equals("n")) //<--- this 'if' block will break the loop when response equals 'n'
{
break;
}
}
}
while (response.equals("n"));// <----- this means doing loop when response equals "n"
You can see my comment on above block of code, the loop will do one more time only when response equals 'n'. But when response equals 'n', the 'if' block at above of it will break the loop and the while (response.equals("n")) will be not checked.

ArrayList If Loop not working properly: JAVA

I have a program that asks the user their name etc. Then it asks how many times do you want the numbers to loop (so my program generates 3 random numbers between 7 and 13 and if it adds up to 31 they are the winner) and my issue is that I only want the last printed number to count towards if the player wins or looses, the other numbers are just for show or tease i guess. the problem is that regardless towards if the player wins or looses, the losing statement always prints out. Below is my entire code.
import java.util.InputMismatchException;
import java.util.Scanner;
import java.io.IOException;
import java.util.Random;
public class StringVariables {
public static void main(String[] args) throws NumberFormatException,
IOException {
// user inputs their name in this section
Scanner user_input = new Scanner(System.in);
//enter their first name
String first_name;
System.out.print("Enter Your First Name: ");
while
(!user_input.hasNext("[A-Za-z]+")) {
System.out.println("Please only enter alphabet characters. Try again.");
user_input.next();
}
first_name = user_input.next();
//enter their last name
String last_name;
System.out.print("Enter Your Last Name: ");
while
(!user_input.hasNext("[A-Za-z]+")) {
System.out.println("Please only enter alphabet characters. Try again.");
user_input.next();
}
last_name = user_input.next();
//full name printed together
String full_name;
full_name = first_name + " " + last_name;
System.out.println(full_name + " Is Now Playing");
// this is the shuffle portion as well as something to see if a number
int numShuffles = -1;
while (numShuffles < 0) {
System.out.println("How many times do you want the numbers shuffled? ");
try {
numShuffles = user_input.nextInt();
} catch (InputMismatchException inputException) {
System.out.print("Please enter a valid number. \n");
//this is the buffer that resets if the user types a letter instead of a number, or any other character
user_input.next();
}
}
// here is going to be the loop for shuffles
// we are now going to generate their random number and add a delay
// after completing their name fields
delay(3000);
System.out
.println(" You will be given " + numShuffles + " hand(s) of 3 random numbers between 7-13" );
delay(2000);
System.out
.println(" Then, the computer will add the random numbers and if it is equal to 31, you win!");
/*
* end of explanation of the game, next i will create a new screen with
* the user's name and numbers
*/
delay(4000);
// printing 25 blank lines
for (int i = 0; i < 25; i++)
System.out.println(" ");
System.out.println("User playing: " + full_name);
System.out.println("Number of times shuffled: " + numShuffles);
System.out.println("Your lucky numbers are...");
// random number generator
Random random = new Random();
while (true) {
// the shuffle loop
Arraylist numberStore = new Arraylist();
boolean isWinner = false;
for (int i = 0; i < numShuffles; i++) {
int num1 = 7 + random.nextInt(7);
int num2 = 7 + random.nextInt(7);
int num3 = 7 + random.nextInt(7);
System.out.println(num1 + " + " + num2 + " + " + num3 + " = " + (num1 + num2 + num3));
numberStore.add(num1 + num2 + num3);
int lastNumber = (numberStore.size() - 1);
if (lastNumber == 31) {
isWinner = true;
System.out.println("Congratulations !! You are the Lucky Winner !!!!");
break;
//if you loose every shuffle
}
}
if (!isWinner) {
System.out.println("Better Luck Next Time");
}
// play again prompt
System.out
.println(" Do you want to play again? (If you do enter y or yes) \n To exit press any other key ");
String input = user_input.next();
if (!"y".equalsIgnoreCase(input) && !"yes".equalsIgnoreCase(input)) {
break;
}
}
// if pressed y or yes the program will run again with the same number of shuffles entered from before
user_input.close();
}
// delay field
public static void delay(int millis) {
try {
Thread.sleep(millis);
} catch (InterruptedException exp) {
// delay field
}
}
}

int lastNumber = (numberStore.size() - 1);
if (lastNumber == 31) {
you probably want something like
int lastNumber = numberStore.get(numberStore.size() - 1);
if (lastNumber == 31) {
to verify that is the error try to change that line to
int lastNumber = num1 + num2 + num3;
Edit based on further messages:
Looks like what you really want is this:
for (int i = 0; i < numShuffles; i++) {
int num1 = 7 + random.nextInt(7);
int num2 = 7 + random.nextInt(7);
int num3 = 7 + random.nextInt(7);
System.out.println(num1 + " + " + num2 + " + " + num3 + " = " + (num1 + num2 + num3));
numberStore.add(num1 + num2 + num3);
int lastNumber = num1 + num2 + num3;
boolean lastShuffle = (i == (numShuffles - 1));
if (lastShuffle) {
if (lastNumber == 31) {
System.out.println("Congratulations !! You are the Lucky Winner !!!!");
} else {
System.out.println("Better Luck Next Time");
}
}
}
// play again prompt
System.out
.println(" Do you want to play again? (If you do enter y or yes) \n To exit press any other key ");
String input = user_input.next();
if (!"y".equalsIgnoreCase(input) && !"yes".equalsIgnoreCase(input)) {
break;
}
Just a general suggestion: avoid to use break if possible, it makes control flow hard to follow and is not a good programming practice.

Several points to make here. One, your code is quite messy and hard to read. It's helpful when you're asking for help (and in general anyway) to properly indent your code. This is good practice and if you do other languages like Python can help you out a lot. Also, why do a check for !isWinner? Scrap the isWinner variable altogether and just check for the number equalling 31 and then have an else statement for the losing statement. Like this:
if (lastNumber == 31) {
System.out.println("Congratulations !! You are the Lucky Winner !!!!");
break;
//if you loose every shuffle
}
else {
System.out.println("Better Luck Next Time");
}
Also, take some steps to find the error. Print out each number as you get it, and use
int lastNumber = num1 + num2 + num3;
instead of
int lastNumber = (numberStore.size() - 1);
Also for anybody else compiling this, it's ArrayList and not Arraylist... just a little slip.

Sorry, I may have to say that your codes are a kind of mess up. a small factory with the solution you ask, hope it can be a little help to you
public static void main(String[] args) throws NumberFormatException,
IOException {
Scanner user_input = new Scanner(System.in);
String full_name = registeGamePlayer(user_input);
int numShuffles = initGame(user_input);
showTheGameInfo(full_name, numShuffles);
runningGame(user_input, numShuffles);
user_input.close();
}
/**
* #param user_input
* #param numShuffles
*/
private static void runningGame(Scanner user_input, int numShuffles) {
// random number generator
Random random = new Random();
while (true) {
// the shuffle loop
boolean isWinner = false;
for (int i = 0; i < numShuffles; i++) {
int num1 = 7 + random.nextInt(7);
int num2 = 7 + random.nextInt(7);
int num3 = 7 + random.nextInt(7);
int amount = num1 + num2 + num3;
System.out.printf("%d + %d + %d = %d \n", num1,num2,num3,amount);
if (amount == 31) {
isWinner = true;
System.out.println("Congratulations !! You are the Lucky Winner !!!!");
break;
// if you loose every shuffle
}
}
if (!isWinner) {
System.out.println("Better Luck Next Time");
}
// play again prompt
System.out.println(" Do you want to play again? (If you do enter y or yes) \n To exit press any other key ");
String input = user_input.next();
if (!"y".equalsIgnoreCase(input) && !"yes".equalsIgnoreCase(input)) {
break;
}
}
}
/**
* #param full_name
* #param numShuffles
*/
private static void showTheGameInfo(String full_name, int numShuffles) {
// printing 25 blank lines
for (int i = 0; i < 25; i++)
System.out.println(" ");
System.out.println("User playing: " + full_name);
System.out.println("Number of times shuffled: " + numShuffles);
System.out.println("Your lucky numbers are...");
}
// delay field
public static void delay(int millis) {
try {
Thread.sleep(millis);
} catch (InterruptedException exp) {
// delay field
}
}
private static String registeGamePlayer(Scanner user_input){
String first_name;
System.out.print("Enter Your First Name: ");
while (!user_input.hasNext("[A-Za-z]+")) {
System.out
.println("Please only enter alphabet characters. Try again.");
user_input.next();
}
first_name = user_input.next();
// enter their last name
String last_name;
System.out.print("Enter Your Last Name: ");
while (!user_input.hasNext("[A-Za-z]+")) {
System.out
.println("Please only enter alphabet characters. Try again.");
user_input.next();
}
last_name = user_input.next();
// full name printed together
String full_name;
full_name = first_name + " " + last_name;
System.out.println(full_name + " Is Now Playing");
return full_name;
}
private static int initGame(Scanner user_input){
// this is the shuffle portion as well as something to see if a number
int numShuffles = -1;
while (numShuffles < 0) {
System.out.println("How many times do you want the numbers shuffled? ");
try {
numShuffles = user_input.nextInt();
} catch (InputMismatchException inputException) {
System.out.print("Please enter a valid number. \n");
// this is the buffer that resets if the user types a letter
// instead of a number, or any other character
user_input.next();
}
}
// here is going to be the loop for shuffles
// we are now going to generate their random number and add a delay
// after completing their name fields
delay(3000);
System.out.println(" You will be given " + numShuffles + " hand(s) of 3 random numbers between 7-13");
delay(2000);
System.out.println(" Then, the computer will add the random numbers and if it is equal to 31, you win!");
/*
* end of explanation of the game, next i will create a new screen with
* the user's name and numbers
*/
delay(4000);
return numShuffles;
}