Java ArrayList - Check if list is empty

Question

How can I check if a list is empty? If so, the system has to give a message saying List is empty. If not, the system has to give a message saying List is not empty. Users can enter numbers, -1 to stop the program. This is the code I now have, but this doesn't work, it always says 'List isn't empty'.

import java.util.*; import javax.swing.JOptionPane;  public class ArrayListEmpty  {     public static void main(String[] args)      {         List<Integer> numbers = new ArrayList<Integer>();         int number;         do {             number = Integer.parseInt(JOptionPane.showInputDialog("Enter a number (-1 to stop)"));             numbers.add(number);         } while (number != -1);         giveList(numbers);     }      public static void giveList(List<Integer> numbers)     {         if (numbers != null)             JOptionPane.showMessageDialog(null, "List isn't empty");         else             JOptionPane.showMessageDialog(null, "List is empty!");     } } 

Answer 1

As simply as:

if (numbers.isEmpty()) {...} 

Note that a quick look at the documentation would have given you that information.

Answer 2

You should use method listName.isEmpty()