how to see if a arraylist is filled or not

Question

Hello I am creating a application that uses arraylists ( practice purposes not real app ) I have created a method that gives me the answer of a math but only if the arraylist contains no object. for some reason I always see the else in my if/else construction.

Here is how I check if the array list contains objects

public void sluitRegistratie() {

    aantalBezoekers = bezoeker.size();

    if(!(aantalBezoekers >= 0)) {

        String str = "Gemiddelde tijd bezoekers: " + (gesommeerdeTijd / aantalBezoekers);

        JOptionPane.showMessageDialog(null, str);
    }
    else {
        JOptionPane.showMessageDialog(null, "Bezoekers zijn nog niet weg");
    }

}

Answer 1

ArrayList has an isEmpty() method that will return true if the arraylist is empty, false otherwise. So it looks like you want if(bezoeker.isEmpty())...

Answer 2

The size of an ArrayList can never be negative, so your check for !size()>=0 will never be true. Just check if size()==0.