Can someone explain why my jar isn't filling with a random number of items?

public class GuessingGame {
    public static void main(String[] args) {
      System.out.println("ADMINISTRATOR SETUP\n********************");

      System.out.println("GUESSING GAME: Guess how many items are in the jar.\n\nSelect the type of items, and how many can reasonably fit in a jar.\nSound good?  Okay let's begin!\n");
      if(args.length != 2) {
        Jar jar = new Jar();
        jar.fillJar();
      }  

    }
    }

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


public class Jar {
  private String itemName;
  private String maxItems;


public Jar() {
  Scanner scanner = new Scanner(System.in);
  System.out.println("What type of item?");
  this.itemName = scanner.nextLine();
  System.out.println("What is the maximum amount of " + itemName + " ?");
  this.maxItems = scanner.nextLine();
  System.out.print("A new jar has been created and filled with " + itemName + ".\n");
  System.out.println("PLAYER\n********************\nHow many " + itemName + " are in the jar?\nPick a number between 1 and " + maxItems);

}
   public void fillJar(randomNumber) {
    Random randomNumber = new Random();
    randomNumber = randomNumber.nextInt(Integer.parseInt(maxItems));
  }

}