OOP) Data Structures

import java.util.ArrayList;
import java.util.HashMap;

public class DataStructures {

    public static void main(String[] args) {

        // for loop
        System.out.println("For Loop:");
        for (int waterLevel = 0 ; waterLevel < 7; waterLevel++){
            System.out.println("The pool's water level is at " + waterLevel + " meters.");
        }

        System.out.println();

        //ArrayList
        System.out.println("ArrayList:");
        ArrayList<Integer> weeklyTemperatures = new ArrayList<Integer>();
            //Insert values to ArrayList
        weeklyTemperatures.add(78);
        weeklyTemperatures.add(67);
        weeklyTemperatures.add(89);
        weeklyTemperatures.add(94);

        System.out.println("Slot 2 = " + weeklyTemperatures.get(1));

            //insert new values to ArrayList
        System.out.println("Insert new value slot 2...");
        weeklyTemperatures.add(1,111);
        System.out.println("Slot 2 = " + weeklyTemperatures.get(1));


            //iterate through ArrayList
        System.out.println();
        System.out.println("Iterating through the ArrayList");
        for (int j = 0; j < weeklyTemperatures.size(); j++){
            System.out.println(weeklyTemperatures.get(j));
        }


        //For Each Loop
        System.out.println();
        System.out.println("For Each Loop: ");
        for (Integer temperature : weeklyTemperatures){
            System.out.println(temperature);
        }


        //HashMap
        System.out.println();
        System.out.println("HashMap: ");
        HashMap<String,Integer> restaurantMenu = new HashMap<String,Integer>();

        restaurantMenu.put("Turkey Burger", 13);
        restaurantMenu.put("Naan Pizza", 11);
        restaurantMenu.put("Cranberry Kale Salad", 10);

        System.out.println(restaurantMenu.size());

        for(String item : restaurantMenu.keySet()){
            System.out.println("A " + item + " costs " + restaurantMenu.get(item) + " dollars");
        }


        //Summary Example
        System.out.println();
        System.out.println("Summary Example:");

        ArrayList<String> sports = new ArrayList<String>();
        sports.add("Football");
        sports.add("Boxing");

        for (String sport : sports){
            System.out.println(sport);
        }

            //Major cities and the year they were founded
        System.out.println();
        HashMap<String,Integer> majorCities = new HashMap<String,Integer>();

        majorCities.put("New York" , 1624);
        majorCities.put("London" , 43);
        majorCities.put("Mexico City" , 1521);
        majorCities.put("Sao Paulo" , 1554);

        for (String city: majorCities.keySet()){
            System.out.println(city + " was founded in " + majorCities.get(city));
        }

    }
}