import java.util.Map;
import java.util.HashMap;

/**
 *  A demo of using Maps in Java.
 */
public class MapExample {
 
    public static void main(String[] args) {
        
        // generics: specify types of keys and values
        Map<String, Integer> citySizes = new HashMap<String, Integer>();
        
        citySizes.put("Portland", 65000);
        citySizes.put("Lewiston", 35000);
        citySizes.put("Brunswick", 20000);
        
        int lewistonPop = citySizes.get("Lewiston");
        
        // loop over keys using for-each style loop
        for (String city : citySizes.keySet()) {
            // get the associated value
            int pop = citySizes.get(city);
            System.out.println("city " + city + " has population of " + pop);
        }
       
    }
    
}