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cannot find symbol error in condition of while loop

I'm writing a program for an assignment that should give random problems for the user to solve. what I am attempting to make it do is after selecting a problem type and answering one question the program should load the menu up again.
Originally I wrote a method that would be called in the else statement on line 147. The method successfully looped however the assignment specifically asks for a loop to make it happen. I've tried several different ways to change the loops condition statement but I'm not sure where I went wrong? any help would be appreciated.
I want very badly to use a switch statement but I can't as we haven't learned that in class.
// Importing Scanner and Random class for later.
import java.util.Scanner;
import java.util.Random;
class AlgebraTutor {
// Solve for Y method.
public static void solve_for_y() {
// Creation of a random number generator.
Random number_gen = new Random();
// Generates random integers from -100 to 100.
int var_m = number_gen.nextInt(101) - 100;
int var_x = number_gen.nextInt(101) - 100;
int var_b = number_gen.nextInt(101) - 100;
// Print problem out for student to see
System.out.println("Problem: y = " + var_m + "(" + var_x +")" + "+" + var_b);
System.out.println(" m =" + var_m);
System.out.println(" x =" + var_x);
System.out.println(" b =" + var_b);
// This formula will calculate the value of y.
float var_y = (var_m * var_x) + var_b;
// Using the scanners class a scanner object called userInput was created to record students answer. Answer was taken as a string and converted to an integer.
Scanner user_input = new Scanner(System.in);
System.out.println("Please solve for y:");
String user_answer = user_input.nextLine();
int answer = Integer.parseInt(user_answer);
if (answer == var_y){
System.out.println("correct");
}else{
System.out.println("incorrect, The answer is:" + var_y);
}
}
// -------------------------------------------------------------------------
// Solve for M method.
public static void solve_for_m() {
// Creation of a random number generator.
Random number_gen = new Random();
// Generates random integers from -100 to 100.
int var_y = number_gen.nextInt(101) - 100;
int var_x = number_gen.nextInt(101) - 100;
int var_b = number_gen.nextInt(101) - 100;
// Print problem out for student to see.
System.out.println("Problem: " + var_y + " = m (" + var_x +") + " + var_b);
System.out.println(" y =" + var_y);
System.out.println(" x =" + var_x);
System.out.println(" b =" + var_b);
// This formula will calculate the value of m.
float var_m = (var_y - var_b) / var_x;
// Using the scanners class a scanner object called userInput was created to record students answer. Answer was taken as a string and converted to an integer.
Scanner user_input = new Scanner(System.in);
System.out.println("Please solve for m:");
String user_answer = user_input.nextLine();
int answer = Integer.parseInt(user_answer);
if (answer == var_m){
System.out.println("correct");
}else{
System.out.println("incorrect, The answer is:" + var_m);
}
}
// -------------------------------------------------------------------------
// Solve for B method
public static void solve_for_b() {
// Creation of a random number generator.
Random number_gen = new Random();
// Generates random integers from -100 to 100.
int var_y = number_gen.nextInt(101) - 100;
int var_x = number_gen.nextInt(101) - 100;
int var_m = number_gen.nextInt(101) - 100;
// Print problem out for student to see.
System.out.println("Problem: " + var_y + " = " + var_m + " (" + var_x +") " + "+ b");
System.out.println(" y =" + var_y);
System.out.println(" x =" + var_x);
System.out.println(" m =" + var_m);
// This formula will calculate the value of m.
float var_b = var_y / (var_m * var_x);
// Using the scanners class a scanner object called userInput was created to record students answer. Answer was taken as a string and converted to an integer.
Scanner user_input = new Scanner(System.in);
System.out.println("Please solve for b:");
String user_answer = user_input.nextLine();
int answer = Integer.parseInt(user_answer);
if (answer == var_b){
System.out.println("correct");
}else{
System.out.println("incorrect, The answer is:" + var_b);
}
}
// -------------------------------------------------------------------------
public static void main(String[] args) {
do{
System.out.println("Which type of problem would you like to practice?");
System.out.println("1) Solve for y");
System.out.println("2) Solve for m");
System.out.println("3) Solve for b");
System.out.println("4) To quit");
Scanner selection_input = new Scanner(System.in);
String user_selection = selection_input.nextLine();
if ( user_selection.equals("1")){
solve_for_y();
} else if (user_selection.equals("2")){
solve_for_m();
} else if (user_selection.equals("3")){
solve_for_b();
} else if (user_selection.equals("4")){
System.out.println("Quitting Program");
System. exit(0);
} else{
System.out.println("Please choose from the given options");
}
} while(user_selection.equals("1") &&
user_selection.equals("2") &&
user_selection.equals("3") &&
user_selection.equals("4"));
}
}

You must declare the user_inpout variable outside the do...while loop, then you can check its value in the while() expression. Also you should initialize the scanner only once at the beginning of your program.
public static void main(String[] args)
{
Scanner selection_input = new Scanner(System.in);
String user_selection=null;
do
{
System.out.println("Which type of problem would you like to practice?");
System.out.println("1) Solve for y");
System.out.println("2) Solve for m");
System.out.println("3) Solve for b");
System.out.println("4) To quit");
user_selection = selection_input.nextLine();
if (user_selection.equals("1"))
{
solve_for_y();
}
else if (user_selection.equals("2"))
{
solve_for_m();
}
else if (user_selection.equals("3"))
{
solve_for_b();
}
else if (user_selection.equals("4"))
{
System.out.println("Quitting Program");
System.exit(0);
}
else
{
System.out.println("Please choose from the given options");
}
}
while (!user_selection.equals("4"));
}
For the case "4" you have two exists now:
else if (user_selection.equals("4"))
{
System.out.println("Quitting Program");
System.exit(0);
}
and:
while (!user_selection.equals("4"));
Only one of both is needed. So you may either remove the first one or replace the while statement by while(true).

Java lottery simulation using Sets, not generating the correct number of random results or comparing Sets correctly

I have been programming a lottery simulation, with some help from questions I've been looking at on this site. I can't seem to get the program to display the correct number of results that I am requiring, and the two sets are not comparing correctly to say how many numbers have matched.
import java.util.Set;
import java.util.HashSet;
import java.util.Random;
import java.util.Scanner;
public class Lotto {
private static final int INPUT_SIZE = 6;
private static final int MIN_NUMBER_POSSIBLE = 1;
private static final int MAX_NUMBER_POSSIBLE = 10;
private Set<Integer> userNumbers = new HashSet<Integer>();
private Set<Integer> randomNumbers = new HashSet<Integer>();
public static void main(String[] args) {
Lotto c = new Lotto();
c.generateRandomNumbers();
System.out.println("Please choose " + INPUT_SIZE + " numbers from " + MIN_NUMBER_POSSIBLE + " to " + MAX_NUMBER_POSSIBLE + ", hit enter after each number.");
c.readUserNumbers();
if (c.doUserNumbersMatchRandomNumbers()) {
System.out.println("Congratulations, you have won!");
} else {
System.out.println("Not a winner, better luck next time.");
c.showRandomNumbersToUser();
}
}
private void generateRandomNumbers() {
Random random = new Random();
for (int i = 0; i < INPUT_SIZE; i++) {
randomNumbers.add(random.nextInt(MAX_NUMBER_POSSIBLE));
}
}
private void showRandomNumbersToUser() {
System.out.println("\nLotto numbers were : ");
for (Integer randomNumber : randomNumbers) {
System.out.println(randomNumber + "\t");
}
}
private void readUserNumbers() {
Scanner input = new Scanner(System.in);
int inputSize = 1;
while (input.hasNextInt() && inputSize < INPUT_SIZE) {
int numberChosen = input.nextInt();
if (numberChosen < MIN_NUMBER_POSSIBLE || numberChosen > MAX_NUMBER_POSSIBLE) {
System.out.println("Your number must be in " + MIN_NUMBER_POSSIBLE + " - " + MAX_NUMBER_POSSIBLE + " range.");
} else {
userNumbers.add(numberChosen);
inputSize++;
}
}
}
private boolean doUserNumbersMatchRandomNumbers() {
for (Integer userNumber : userNumbers) {
for (Integer randomNumber : randomNumbers) {
if (!randomNumbers.contains(userNumber)) {
return false;
}
}
printMatchingNumber(userNumber);
}
return true;
}
private void printMatchingNumber(int num) {
System.out.println("Your number, " + num + ", has been drawn.");
}
}

There 2 problems in your code:
1) In generateRandomNumbers you should take into account that the same random number could occur multiple times. So make sure that randomNumbers is really of INPUT_SIZE size in the end.
2) In doUserNumbersMatchRandomNumbers you iterate over randomNumbers but never use randomNumber.

You store your random numbers in a (Hash-)Set, One feature of Set as described in the API is that they do not contain duplicate values (by comparing them with their equals() method). Since the Random class may output the the same value multiple times you have less values in your Set.
The better approach for generating the random numbers would be to go with a while loop:
while (random.size() < INPUT_SIZE)
{
randomNumbers.add(random.nextInt(MAX_NUMBER_POSSIBLE));
}
keep in mind that this could result in an endless loop. Although it is very unlikely though. At least this loop does have varying execution times.

Java / Creating hi/low game using multiple methods, stuck at returning no. of guesses

I'm creating a high/low guessing game as part of a study assignment, and the part im stuck at is getting the amount of guesses returned to the main method. We have specifically been told that the main method has to print the number of guesses, while the method "playGame" actually does the playing.
There's more to the code, a method called giveReponse that checks if the number is correct or too high/low, but it works as intended. I get "Cannot find symbol" when trying to print how many guesses it took to complete the game.
If it wasn't so important to print it in the main method I'd print the amount in the method playGame, but thats a no-go. What am I doing wrong?
The code looks like this:
public class HiLo {
public static void main(String[] args) {
Scanner scan = new Scanner(System.in);
System.out.println("Welcome to classic guessing game of high/low!");
String difficulty = scan.next();
if (difficulty.equals("easy")) {
playGame(10);
} else if (difficulty.equals("medium")) {
playGame(100);
} else if (difficulty.equals("hard")) {
playGame(1000);
}
System.out.println("You won in" + guesses + "attempts.");
}//EndsMain
public static int playGame(int maxNumber) {
Scanner scan = new Scanner(System.in);
int rannr = (int)(Math.random() * maxNumber) +1;
int answer = rannr;
int guess = 0;
int guesses = 0;
System.out.println("Game is starting...");
do {
guess = scan.nextInt();
guesses ++;
giveResponse(answer, guess);
if (answer == guess) {
break;
}
} while (answer != guess);
return guesses;
} //Ends playGame

Your method playGame( ) is returning a value but since is not assigned to no variable, those returns are getting lost...
additional to that it looks like the code is not complete:
this statement is not going to let you compile:
System.out.println("You won in" + guesses + "attempts.");
because the only guesses variable I see in there is scoped in the playGame method....
do instead something like:
public static void main(String[] args) {
Scanner scan = new Scanner(System.in);
System.out.println("Welcome to classic guessing game of high/low!");
int guesses = 0;
String difficulty = scan.next();
if (difficulty.equals("easy")) {
guesses = playGame(10);
} else if (difficulty.equals("medium")) {
guesses = playGame(100);
} else if (difficulty.equals("hard")) {
guesses = playGame(1000);
}

The problem is at:
System.out.println("You won in" + guesses + "attempts.");
Since the variable guesses is not defined in the main method, the compiler doesn't know what you are referencing to with that symbol.
But since playGame() returns the number of guesses, I'd recommend something like this:
if (difficulty.equals("easy")) {
System.out.println("You won in" +playGame(10)+ "attempts.");
} else if (difficulty.equals("medium")) {
System.out.println("You won in" +playGame(100)+ "attempts.");
} else if (difficulty.equals("hard")) {
System.out.println("You won in" +playGame(1000)+ "attempts.");
}

Here's a solution that shows how easy it would be to restrict guesses. Not much extra effort or thought:
package games;
import java.util.Random;
import java.util.Scanner;
/**
* HiLo guessing game
* Created by Michael
* Creation date 4/9/2016.
* #link https://stackoverflow.com/questions/36522303/java-creating-hi-low-game-using-multiple-methods-stuck-at-returning-no-of-gu
*/
public class HiLo {
public static void main(String [] args) {
int maxValue = (args.length > 0) ? Integer.parseInt(args[0]) : 100;
int maxGuesses = (args.length > 1) ? Integer.parseInt(args[1]) : 5;
Scanner scanner = new Scanner(System.in);
String answer = "Y";
do {
play(scanner, maxValue, maxGuesses);
System.out.println("Play again? [Y/N]: ");
answer = scanner.next();
System.out.println(String.format("You answered %s; let's play again!", answer));
} while ("Y".equalsIgnoreCase(answer));
}
private static void play(Scanner scanner, int maxValue, int maxGuesses) {
int value = new Random().nextInt(maxValue) + 1;
int numGuesses = 0;
boolean match = false;
do {
System.out.println(String.format("Guess a value between 1 and %d: ", maxValue));
int guess = Integer.parseInt(scanner.next());
if (guess < value) {
System.out.println(String.format("Too low; guess again. (%d guesses left)", (maxGuesses-numGuesses-1)));
} else if (guess > value) {
System.out.println(String.format("Too high; guess again (%d guesses left)", (maxGuesses-numGuesses-1)));
} else {
match = true;
System.out.println(String.format("You got it right in %d guesses! ", numGuesses+1));
break;
}
} while (!match && ++numGuesses < maxGuesses);
if (!match) {
System.out.println(String.format("The correct answer was %d; you're only allowed %d guesses. Better luck next time!", value, maxGuesses));
}
}
}

Having An Issue With Randomly Generated Numbers - Java

I am working on this project from the Java Programming book by Joyce Farrell, and I am having an issue with the Randomly Generated number and the user's guesses not being checked correctly. For example the user has 3 guesses, lets say their first guess it 2 and the first randomly generated number is 2 the program will print out You lose. When the guess is actually correct. Please help me. I have added the details of the program plus what I have done so far.
Create a lottery game application. Generate three random numbers (see Appendix D for help in
doing so), each between 0 and 9. Allow the user to guess three numbers. Compare each of the
user's guesses to the three random numbers and display a message that includes the user's
guess, the randomly determined three-digit number, and the amount of money the user has
won as follows.
Matching Numbers Award($)
Any one matching 10
Two matching 100
Three matching, not in order 1000
Three matching, in exact order 1,000,000
No match 0
Make certain that your application accommodates repeating digits. For example, if a user
guesses 1, 2, and 3, and the randomly generated digits are 1, 1, and 1, do not give the user
credit for three correct guesses - just one. Save the file as Lottery.
My Source Code
// Filename: Lottery.java
// Written by: Andy A
// Written on: 14 January 2015
import java.util.Scanner;
import java.util.Random;
public class Lottery {
public static void main(String[] args) {
Scanner userInput = new Scanner(System.in);
Random ranNum = new Random();
// LIMIT Contains The Numbers From 0 - 9
// TIMES Contains The Number of Time ranNum Should Run
final int LIMIT = 9;
final int TIMES = 3;
// Users Guesses
int usersFirstGuess;
int usersSecondGuess;
int usersThirdGuess;
// Randomly Generated Numbers
final int GenFirst = ranNum.nextInt(LIMIT);
final int GenSecond = ranNum.nextInt(LIMIT);
final int GenThird = ranNum.nextInt(LIMIT);
// User is asked for 3 guesses
System.out.println("Please enter your first guess: ");
usersFirstGuess = userInput.nextInt();
System.out.println("Please enter your second guess: ");
usersSecondGuess = userInput.nextInt();
System.out.println("Please enter your third and final guess: ");
usersThirdGuess = userInput.nextInt();
// Winning Amounts
final double WinTen = 10;
final double WinHun = 100;
final double WinThund = 1000;
final double WinMillion = 1000000;
final int WinZero = 0;
// Shows the randomly generated numbers
for(int x = 0; x < TIMES; ++x)
System.out.print(ranNum.nextInt(LIMIT) + " ");
System.out.println();
// First Generated
if(GenFirst == usersFirstGuess ) {
System.out.println("You have won: $" + WinTen);
}
else if(GenSecond == usersSecondGuess) {
System.out.println("You have won: $" + WinTen);
}
else if(GenThird == usersThirdGuess) {
System.out.println("You have won: $" + WinTen);
}
}
}

You are printing newly generated numbers with ranNum.nextInt(LIMIT), however you are comparing the user input with the numbers stored in the GenXXX variables.
Solution: Print the variables instead.
System.out.println(GenFirst + " " + GenSecond + " " + GenThird);
If you still want to use a loop for printing you can store the numbers in an array.
// generate
final int[] generated = new int[TIMES];
for (int x = 0; x < TIMES; x++)
generated[x] = ranNum.nextInt(LIMIT);
// print
for (int x = 0; x < TIMES; x++)
System.out.print(generated[x] + " ");

This should do the trick.
// Filename: Lottery.java
// Written by: Andy A
// Written on: 14 January 2015
import java.util.ArrayList;
import java.util.List;
import java.util.Scanner;
import java.util.Random;
public class Lottery {
public static void main(String[] args) {
Scanner userInput = new Scanner(System.in);
Random ranNum = new Random();
// LIMIT Contains The Numbers From 0 - 9
// TIMES Contains The Number of Time ranNum Should Run
final int LIMIT = 9;
final int TIMES = 3;
// Users Guesses
int usersFirstGuess;
int usersSecondGuess;
int usersThirdGuess;
List<Integer> guesses = new ArrayList<>();
// Randomly Generated Numbers
final int GenFirst = ranNum.nextInt(LIMIT);
final int GenSecond = ranNum.nextInt(LIMIT);
final int GenThird = ranNum.nextInt(LIMIT);
// User is asked for 3 guesses
System.out.println("Please enter your first guess: ");
usersFirstGuess = userInput.nextInt();
guesses.add(usersFirstGuess);
System.out.println("Please enter your second guess: ");
usersSecondGuess = userInput.nextInt();
guesses.add(usersSecondGuess);
System.out.println("Please enter your third and final guess: ");
usersThirdGuess = userInput.nextInt();
guesses.add(usersThirdGuess);
// Winning Amounts
final double WinTen = 10;
final double WinHun = 100;
final double WinThund = 1000;
final double WinMillion = 1000000;
final int WinZero = 0;
// Shows the randomly generated numbers
System.out.println(GenFirst + " " + GenSecond + " " + GenThird);
List<Integer> lottery = new ArrayList<>();
lottery.add(GenFirst);
lottery.add(GenSecond);
lottery.add(GenThird);
if (guesses.equals(lottery)) {
System.out.println("You have won: $" + WinMillion);
} else {
int matchCount = 0;
for (Integer guessValue : guesses) {
if (lottery.contains(guessValue)) {
matchCount++;
lottery.remove(guessValue);
}
}
switch (matchCount) {
case 0:
System.out.println("You have won: $" + WinZero);
break;
case 1:
System.out.println("You have won: $" + WinTen);
break;
case 2:
System.out.println("You have won: $" + WinHun);
break;
case 3:
System.out.println("You have won: $" + WinThund);
break;
}
}
}
}

Exactly,
why are you printing
System.out.print(ranNum.nextInt(LIMIT) + " ");
when you should be just printing
System.out.print(GenThird + " ");
System.out.print(GenSecond + " ");
System.out.print(GenFirst + " ");

This is not the problem of the randomly generated numbers, but if your way of showing them to the user.
Before your if / else if statements, in the for-loop you are generating new random numbers. That means, the number compared to the users input (genFirst) can be 3, but the number shown to the user in the for loop is a new random number, for example 2.
To fix this problem, you should display the generated numbers like that:
for (int ranInt : new int[] { GenFirst, GenSecond, GenThird}) {
System.out.println(ranInt);
}
This piece of code creates an array of the generated numbers and loops through them printing them. Obviously, you can also print GenFirst, then print GenSecond and then print GenThird.
I hope this helps!

Maybe this will help!
import java.util.Scanner;
import java.util.Random;
public class Qellonumrat {
public static void main(String[] args) {
Scanner sc=new Scanner(System.in);
Random rand=new Random();
int random_integer=(int) rand.nextInt(10);
System.out.println("Guess the number: ");
int number=sc.nextInt();
while(true){
if(number == random_integer){
random_integer++;
System.out.println("Congrats you won!!!");
break;
}
else{
System.out.println("Try again");
break;
}
}
}
}

Random number guessing game with if statement and a for loop Java

My name is Fermin. I'm new in this forum and I'm also studying Java to be a Java developer. I'm stuck on an assignment and I would like some help from anyone. Here is the description and the code
Using an if statement in the for block, determine
whether randNum and guessNum are equal.
public class GuessGame {
/**
* #param args the command line arguments
*/
public static void main(String[] args) {
int randNum , guessNum ;
//Generates a random number from 1 to 10
randNum = new java.util.Random().nextInt(10) + 1;
System.out.println("Im thinking of a number from 1 to 10");
for (guessNum = 0; guessNum <= 10; guessNum ++){
java.util.Scanner scan = new java.util.Scanner(System.in);
guessNum = scan.nextInt();
if (guessNum == randNum) {
System.out.println("you guess" + guessNum );
}
}
}
}
Updated code
import java.util.Random;
import java.util.Scanner;
public class NumberGuess {
public static void main(String[] args) {
Scanner scan = new Scanner(System.in);
Random rand = new Random();
System.out.println("Im thinking of a number from 1 to 10");
int number = scan.nextInt(10);
//Generates a random number from 1 to 10
int number2 = rand.nextInt(10)+1;
System.out.println("you enter the number" + " " + number);
for (int counter = -1; counter < 3; counter ++ ){
if(number!= number2)
System.out.println("and your random number is:" + " " + number2 + " " + "please try again");
else
System.out.println("your guess number is equal to the random number Good job guessing");
break;
}
}
}

Your for loop is controlled by the guessNum variable. Within the loop, you're reassigning that variable's value when you do this:
guessNum = scan.nextInt();
As a result, you're likely getting an inconsistent number of loops because you're changing the variable that the loop relies on for control.
Given the name of this variable, I suspect you originally intended it to be used to store the user's input. If that is the case, I would alter your for loop to use a different variable instead, like so:
for (int guessCount = 0; guessCount < 10; guessCount++){
Also note, your condition originally had <= 10; since your counting variable started at zero, this will allow the user 11 guesses, rather than 10 (since 0 to 10 inclusive = 11). Assuming you wanted 10 guesses instead, you will want to check for less than 10 (since 0..10 exclusive = 10).

import java.util.Random;
import java.util.Scanner;
public class NumberGuess {
public static void main(String[] args) {
Scanner scan = new Scanner(System.in);
Random rand = new Random();
System.out.println("Im thinking of a number from 1 to 10");
int number = scan.nextInt(10);
//Generates a random number from 1 to 10
int number2 = rand.nextInt(10)+1;
System.out.println("you enter the number" + " " + number);
for (int counter = -1; counter < 3; counter ++ ){
if(number!= number2)
System.out.println("and your random number is:" + " " + number2 + " " + "please try again");
else
System.out.println("your guess number is equal to the random number Good job guessing");
break;
}
}
}