Beginning "While" Program Help

[Sam Pauken]

I'm trying to figure out what's wrong with the code below. Could someone give me a nudge in the right direction please?

package itp120mod3abstart;

import java.util.Scanner;

public class GuessingGame {
	
	public static void main(String[] args) {
		
		{
			Scanner scan = new Scanner (System.in);
			String again = "yes";
			boolean correct = false;
				
			int num;
			num = (int) (Math.random()*20) +1;
			System.out.println("What is the number: " );
			int guess = scan.nextInt();
			int numGuesses = 1;
			
			
			while (correct != 999)	{
				if (guess=999) {
					System.out.println("You guessed correctly!  It took you " + numGuesses + " guesses.");
					correct = true;}
				else if (guess>=num) {
					System.out.println("Your guess was high, guess again.");
					numGuesses=numGuesses+1;}
				else {
					System.out.println("Your guess was low, guess again.");
					numGuesses=numGuesses+1;}}
			
			correct = false;
		
			}
		}	
		
	}					
	
				// set the String again equal to yes
	//set the boolean correct equal to false
		
		//top of outside loop
		//while again equals yes
		//NOTE: To do this, make certain to use .equals instead of ==.  == can only be used for primitive types
		
			// get a random number between 1 and 20 and set it equal to the variable num
			//ask the user for their guess
			// store their answer in the variable named guess
			// declare a variable named numGuesses and set it equal to one
		
			//start of inner loop
			// use a while loop and continue as long as the  variable correct equals false
				// if their guess is the same as the variable num, tell them so and set the variable correct to true.  Tell them how many guesses it took.
				//else if their guess is larger than the variable num, tell them so and let them guess again. Increment numGuesses.
				//else if their guess is smaller than the variable num, tell them so and let them guess again. Increment numGuesses.
			// end of inner loop
			// set correct back to false getting ready for the next loop
			// ask them if they want to play again and store their answer in the variable named again.  You need an extra input.nextLine()

[Steve Luke]

Sam Pauken wrote:I'm trying to figure out what's wrong with the code below. Could someone give me a nudge in the right direction please?

Why do you think there is something wrong with the code? Do you get an error? Does it misbehave when you run it? TellTheDetails please.

[Sam Pauken]

For "correct != 999, I'm told that "The operator != is undefined for the argument type(s) boolean, int". For guess=999, I'm told "Type mismatch: cannot convert from int to boolean". In the directions in the code, I'm supposed to assign the bollean to false, so I'm not sure how to proceed.

while (correct != 999)	{
				if (guess=999)

[Bear Bibeault]

The variable correct is declared as a boolean. So it can only attain the values true and false. 999 is not a boolean.

[Bear Bibeault]

If you just want to loop until correct is false:

while (correct) {
. . .
}

[Bear Bibeault]

Also please take better care with your indentation and matching up braces. That's an important tool for inspecting the structure of the program.

[Sam Pauken]

I've made a lot of progress. I am able to reach the point where I am asked if I want to play again and I get this stack trace.

Exception in thread "main" java.lang.NullPointerException
at itp120mod3abstart.GuessingGame.main(GuessingGame.java:42)

How I use input.nextLine() correctly here? I need to be able to say "yes" in order to restart, else the program stops.

package itp120mod3abstart;

import java.util.Scanner;

public class GuessingGame {
	
	private static Scanner input;

	// program generates a random number between 1 and 20
	// and asks player to guess answer.  Continues until 
	// number is guessed.
	
	public static void main(String[] args) {
		
		{
			Scanner scan = new Scanner (System.in);
			String again = "yes";
			
			while (again.equalsIgnoreCase("yes"))
			
			{
				int num;
				num = (int) (Math.random()*20) +1;
				int guess = 0;
				int numGuesses = 1;
			
				while (guess!=num)
				{	
					System.out.println("What is the number: " );
					guess = scan.nextInt();
					if (guess==num) {
						System.out.println("You guessed correctly!  It took you " + numGuesses + " guesses.");
						}
					else if (guess>=num) {
						System.out.println("Your guess was high, guess again.");
						numGuesses=numGuesses+1;}
					else {
						System.out.println("Your guess was low, guess again.");
						numGuesses=numGuesses+1;}}
					
					System.out.println("Do you want to play again?");
					again=input.nextLine();
				}	
			}
		}	
		
	}	

[Saket Barve]

Variable input is not initialized and your main method is using variable scan

[Winston Gutkowski]

Sam Pauken wrote:I'm trying to figure out what's wrong with the code below.

Sam,

Please DontWriteLongLines.
It makes your thread very hard to read, and it's actually bad coding practice.

I'd break yours up myself, but you have tons of them (and in more than one post), so perhaps you could do it?
Just use the 'Edit' button.

And for future reference, please remember:
80 characters max.
(the SSCCE page actually recommends 62)
And that includes string literals AND comments AND long method calls.

Thanks.

Winston

[Sam Pauken]

I got it! Thank you all for your help with my n00b questions.