Random number generator always returning 0 when given a range

I'm making a guessing game where the user sets the maximum number and that number is used for the range for the random number generator, but every time I test my program it outputs 0. I'm not sure why.

import java.util.Scanner;
import java.util.Random;

public class GuessingGame {

public static Scanner scan = new Scanner (System.in);
public static Random random = new Random();

public static int answer;  
public static int maxNumber;  
public static int minNumber = 0;              

public static void main (String [] args ){                     
                            
  System.out.println("Welcome to the Guessing Game.");
  System.out.println("Enter the maximum number.");
  int maxNumber = scan.nextInt(); 
  System.out.println(answer); //Remove after testing 
} 
 public static int newGame(Random random) {  
  int randNumber;
  int range = maxNumber - minNumber; 
  randNumber = random.nextInt(range);                                 
  answer = randNumber;     
     return answer;     
}                    

You did not call the public static int newGame(Random random) function. In java the default value of an integer is 0.

You did not call the function, so it did not change the value of answer.

Also if you don't want an extra method for this you can use the following:

public static void main (String [] args ){                     
                            
  System.out.println("Welcome to the Guessing Game.");
  System.out.println("Enter the maximum number.");
  int maxNumber = scan.nextInt(); 
  answer = new Random().nextInt(maxNumber - minNumber);
  System.out.println(answer); //Remove after testing 
} 

Or if you want to use the method:

public static void main (String [] args ){                     
                            
  System.out.println("Welcome to the Guessing Game.");
  System.out.println("Enter the maximum number.");
  maxNumber = scan.nextInt(); 
  answer = newGame(random);
  System.out.println(answer); //Remove after testing 
} 

public static int newGame(Random random) {  
  int range = maxNumber - minNumber; 
  return random.nextInt(range);      
} 

You have NOT called the function newGame in main!
You may have to do this in main:

System.out.println(newGame(random));

OR:

answer = newGame(random);
System.out.println(answer);

You may want to look at this function:

public static int randNum(int min, int max)	{
		Random rand = new Random();
		int val = Math.abs(rand.nextInt());
		val = (val % (max - min + 1)) + min;
		
		return val;
	}

This function is to randomize a non-negative number between min and max. You can let it min = 0 or just eliminate min from the formula if you just need any non-negative number.

Add this line after scan.nextInt():

answer = newGame(random);

Also, there's a bug in your newGame method. Change:

answer = randNumber; 

to

answer = randNumber + minNumber;