Array List

import java.util.ArrayList; // importing the ArrayList Class

class ShapesClass {
  public static void main( String args[] ) {
    ArrayList<String> shapes = new ArrayList<String>(); //create an ArrayList with string data type
    //Add a bunch of shapes to start off.
    shapes.add("square");    
    shapes.add("triangle");  
    shapes.add("hexagon");  
    shapes.add("rhombus");    
    shapes.add("octagon");    
    shapes.add("rectangle");  
    shapes.add("pentagon");   

    //Print all the shapes
    System.out.println("Shapes in ArrayList:");
    System.out.println(shapes); // prints all elements of ArrayList shapes
    System.out.println();

    //Get element at index 4
    System.out.println("Element at index 4:");
    System.out.println(shapes.get(4)); // print element at index 4
    System.out.println();

    //Remove elements at 3 and 5 but have to remove 3 and 4 since removing 3 takes 5 down by 1.
    System.out.println("Remove elements at index 3 and 5:");
    shapes.remove(3);          // removing element at index 3
    shapes.remove(4);          // removing element at index 5 since removing 3 moves the index down 1.
    System.out.println(shapes); // prints all elements of ArrayList shapes
    System.out.println();

    //Set index 4 as "circle"
    System.out.println("Set index 4 as circle:");
    shapes.set(4,"circle");     // replaces element at index 4 with circle
    System.out.println(shapes); // prints all elements of ArrayList shapes
    System.out.println();

    //Get the total number of elements in ArrayList
    System.out.println("Number of elements in ArrayList:");
    System.out.println(shapes.size()); // prints the number of elements in the ArrayList 
    System.out.println();

    //Add a second hexagon and get the index of the first one
    System.out.println("Add hexagon:");
    shapes.add("hexagon");             // Adds hexagon
    System.out.println(shapes); // prints all elements of ArrayList shapes
    System.out.println("Get 1st hexagon index:");
    System.out.println(shapes.indexOf("hexagon"));
    System.out.println();

    //Clear the ArrayList
    System.out.println("Clear ArrayList:");
    shapes.clear();             // removes all elements in the ArrayList
    System.out.println(shapes); // prints all elements of ArrayList shapes
    System.out.println();
    
  }
}

ShapesClass.main(null);

Shapes in ArrayList:
[square, triangle, hexagon, rhombus, octagon, rectangle, pentagon]

Element at index 4:
octagon

Remove elements at index 3 and 5:
[square, triangle, hexagon, octagon, pentagon]

Set index 4 as circle:
[square, triangle, hexagon, octagon, circle]

Number of elements in ArrayList:
5

Add hexagon:
[square, triangle, hexagon, octagon, circle, hexagon]
Get 1st hexagon index:
2

Clear ArrayList:
[]