Question

When I tried to build this program there’s always a error like “non-static method referenced from a static context”
I think that because I can use “addto” function in “main”. So how can I solve this problem? I need a public arraylist because I have to do the calculations in “addto”

Thx!

public class Calculation {  
    ArrayList<int[]> cal = new ArrayList<>();

    public static void main(String[] args) {
    System.out.println(addto(3,5));
    }

    String addto(int figone, int figtwo){
     ........do the calculations by using arraylist cal
    }
 }

Answer 1

Really simple?

System.out.println(new Calculation().addto(3,5));

or

Calculation calculation = new Calculation();
System.out.println(calculation.addto(3,5));
// and use 'calculation' some more ...

(You could also add a static modifier to the addto method declaration, but you would then need to make cal static too so the addto can use it. Bad idea.)

---

OK. So what the compilation method is actually saying is that addto is declared as an instance method … but you are trying to call it without saying which instance to use. In fact, you are trying to call it as if it was a static method.

The “fix” (see above) is to create an instance and call the method on that.