What does the method size() do in java?

The size() method of the class java.util.ArrayList returns the number of elements in this list i.e. the size of the list.

Example

import java.util.ArrayList;

public class ArrayListDemo {
   public static void main(String[] args) {
      ArrayList<Integer> arrlist = new ArrayList<Integer>(5);
      arrlist.add(15);
      arrlist.add(20);
      arrlist.add(25);
      arrlist.add(22);
      for (Integer number : arrlist) {
         System.out.println("Number = " + number);
      }
      int retval = arrlist.size();
      System.out.println("Size of list = " + retval);
   }
}

Output

Number = 15
Number = 20
Number = 25
Number = 22
Size of list = 4