java ArrayList demo

ArrayList in Java is a data structure that’s similar to array but with more convienient methods that you can use to add, remove, update elements from the ArrayList list easily. Unlike array that you have to defined the size of your data at the time of array declaration, ArrayList allows you to dynamically increase or decrease the size of the list by adding or removing the items from the list. The ArrayList demo below shows the usage of add, remove and set methods from the ArrayList.

import java.util.ArrayList;
public class ArrayListDemo
{
   public  static void main(String[] args)
   {
      // Declaring an ArrayList for storing strings
      ArrayList<String> str = new ArrayList<String>();
      str.add("aaaaaa"); display(str);
      str.add("bbbbbb"); display(str);
      str.add("cccccc"); display(str);
      str.add(2, "dddddd"); display(str);
      str.remove(1); display(str);
      str.set(0, "eeeeee"); display(str);
   }
   public static void display(ArrayList<String> str)  
   {
      System.out.println("\nThe size of the list is " + str.size());
      for(int x = 0; x < str.size(); ++x)
         System.out.println("position " + x + " str: " + str.get(x));
   }
}

Output:

The size of the list is 1
position 0 str: aaaaaa

The size of the list is 2
position 0 str: aaaaaa
position 1 str: bbbbbb

The size of the list is 3
position 0 str: aaaaaa
position 1 str: bbbbbb
position 2 str: cccccc

The size of the list is 4
position 0 str: aaaaaa
position 1 str: bbbbbb
position 2 str: dddddd
position 3 str: cccccc

The size of the list is 3
position 0 str: aaaaaa
position 1 str: dddddd
position 2 str: cccccc

The size of the list is 3
position 0 str: eeeeee
position 1 str: dddddd
position 2 str: cccccc