FAQ: Static Variables and Methods - Writing Your Own Static Methods

This community-built FAQ covers the “Writing Your Own Static Methods” exercise from the lesson “Static Variables and Methods”.

Paths and Courses
This exercise can be found in the following Codecademy content:

Learn Java

FAQs on the exercise Writing Your Own Static Methods

There are currently no frequently asked questions associated with this exercise – that’s where you come in! You can contribute to this section by offering your own questions, answers, or clarifications on this exercise. Ask or answer a question by clicking reply (reply) below.

If you’ve had an “aha” moment about the concepts, formatting, syntax, or anything else with this exercise, consider sharing those insights! Teaching others and answering their questions is one of the best ways to learn and stay sharp.

Join the Discussion. Help a fellow learner on their journey.

Ask or answer a question about this exercise by clicking reply (reply) below!
You can also find further discussion and get answers to your questions over in #get-help.

Agree with a comment or answer? Like (like) to up-vote the contribution!

Need broader help or resources? Head to #get-help and #community:tips-and-resources. If you are wanting feedback or inspiration for a project, check out #project.

Looking for motivation to keep learning? Join our wider discussions in #community

Learn more about how to use this guide.

Found a bug? Report it online, or post in #community:Codecademy-Bug-Reporting

Have a question about your account or billing? Reach out to our customer support team!

None of the above? Find out where to ask other questions here!

public class ATM{
  // Static variables
  public static int totalMoney = 0;
  public static int numATMs = 0;

  // Instance variables
  public int money;

  public ATM(int inputMoney){
    this.money = inputMoney;
    numATMs += 1;
    totalMoney += inputMoney;
  }

  public void withdrawMoney(int amountToWithdraw){
    if(amountToWithdraw <= this.money){
      this.money -= amountToWithdraw;
      totalMoney -= amountToWithdraw;
    }
  }

  // Write your averageMoney() method here
  public static void averageMoney(){
    System.out.println(totalMoney / numATMs);
  }
  public static void main(String[] args){

    System.out.println("Total number of ATMs: " + ATM.numATMs); 
    ATM firstATM = new ATM(1000);
    ATM secondATM = new ATM(500);
    System.out.println("Total number of ATMs: " + ATM.numATMs); 

    System.out.println("Total amount of money in all ATMs: " + ATM.totalMoney);  
    firstATM.withdrawMoney(500);
    secondATM.withdrawMoney(200);
    System.out.println("Total amount of money in all ATMs: " + ATM.totalMoney);    

    // Call averageMoney() here
  ATM.averageMoney();
  System.out.println(this.money);
  }

}

So one thing I don’t understand about the last part of the instructions is that “System.out.println(this.money);” is an error. If you go up it shows that money is not a static class. It just says “public int money;” how does this produce an error?

I think it produces an error because this there’s no this inside the static method main.
(You could do firstATM.money instead.)

Why does the exercise say to use ATM.averageMoney(); when just using averageMoney(); works exactly the same?