import java.util.List;
import java.util.ArrayList;

/**
 *  A demo of basic list functionality (and a comparison with arrays).
 */
public class ListExample {
    
    /**
     * Build a list of the squares of 0 to numSquares.
     */
    public static List<Integer> buildSquaresList(int numSquares) {
        List<Integer> squares = new ArrayList<Integer>();
        for (int i = 0; i < numSquares; i++) {
            squares.add(i * i); // or squares.set(i, i * i)
        }
        return squares;
    }
    
    /**
     * Build an array of the squares of 0 to numSquares.
     */
    public static int[] buildSquaresArray(int numSquares) {
        int[] squares = new int[numSquares];
        for (int i = 0; i < numSquares; i++) {
            squares[i] = i * i;
        }
        return squares;
    }
    
    /**
     * A simple demo of arrays and lists.
     */
    public static void main(String[] args) {
        
        // build the array/list
        int[] squaresArray = buildSquaresArray(10);
        List<Integer> squaresList = buildSquaresList(10);
      
        // get the first element
        int firstArrayEl = squaresArray[0];
        int firstListEl = squaresList.get(0);
      
        // get the last element
        int lastArrayEl = squaresArray[squaresArray.length - 1];
        int lastListEl = squaresList.get(squaresList.size() - 1);
      
        // replace the element at position 3 (the 4th element)
        squaresArray[3] = 25;
        squaresList.set(3, 25); // note: set method returns replaced element
        
        // print the array elements
        for (int i = 0; i < squaresArray.length; i++) {
            int element = squaresArray[i];
            System.out.println(element);
        }
        
        // print the list elements
        for (int i = 0; i < squaresList.size(); i++) {
            int element = squaresList.get(i);
            System.out.println(element);
        }
        
        // for-each loop syntax
        for (int element : squaresList) {
            System.out.println(element); 
        }
        
    }
    
}