import java.util.HashMap;
import java.util.Map;
public class Main {
public static void main(String[] args) {
Map<String, String> map = new HashMap<String, String>();
map.put("first_name", "Alvin");
map.put("last_name", "Alexander");
// java 8
map.forEach((k,v)->System.out.println("key: " + k + ", value: " + v));
// prior to java 8
for (Map.Entry<String, String> entry : map.entrySet()) {
System.out.println("key: " + entry.getKey() + ", value: " + entry.getValue());
}
}
}