Java referencing an ArrayList from method outside of main method

Question

So I have the following array list:

ArrayList <Employee> employees = new ArrayList<>();

In my main method I create instances of them

public static void main(String[] args){
     Employee test = new Manager("john doe", 1000); //manager is subclass

}

I have a method that checks that the employee object doesn't already exist, the equals method is defined in the subclasses

public void addEmployee(Employee newEmployee){
    for (int i  = 0; i < employees.size(); i++){
           if(newEmployee.equals(employees.get(i))){
               .........
           }
       }
 }

Theres more to it above, but you get the point. I need to reference the ArrayList, but if I instantiate the array list outside of the main method I can't add any variables to it, getting the error "non-static method cannot be referenced from static context" which makes sense, but I don't know how to use that method then since I can't declare it in the main method.

How are these three segments of code even related? It's not clear what you're trying to do or what's preventing you. — David
– David, Commented Apr 3, 2015 at 23:31
declare the test variable as static? I do that and I get an error saying illegal start of expression — Burninrock24
– Burninrock24, Commented Apr 3, 2015 at 23:31
@David it's a watered down version of all my code. I have a main superclass of employee, a subclass of manager, and subclass of worker, then this main class that tests the methods and constructors and such. — Burninrock24
– Burninrock24, Commented Apr 3, 2015 at 23:33
seems like a Set would be a more suitable container than an ArrayList — muued
– muued, Commented Apr 3, 2015 at 23:34

candied_orange · Accepted Answer · 2015-04-03 23:38:55Z

2

Unless you want to create a class for managing employee's you'll want to make your method and collection static

static ArrayList <Employee> employees = new ArrayList<>();

public static void addEmployee(Employee newEmployee){
    for (int i  = 0; i < employees.size(); i++){
           if(newEmployee.equals(employees.get(i))){
               .........
           }
       }
 }

@muued has a point. There are other data structures in java then ArrayList. When in doubt I look at this:

enter image description here

edited Apr 3, 2015 at 23:38

answered Apr 3, 2015 at 23:31

candied_orange

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4 Comments

Burninrock24 Over a year ago

Thanks, I wasn't aware that I could declare ArrayList as static like that and still allow it to have it's elements be modified and still function properly.

candied_orange Over a year ago

@BoristheSpider deserves the credit for that. He spotted it first.

Burninrock24 Over a year ago

I'm new to this place is there a way to give him the best answer?

candied_orange Over a year ago

He didn't post an answer but his comment can be upvoted.

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