java 8 - Why does Java8 Stream generate nothing? -

import java.util.comparator; import java.util.priorityqueue;   public class testpq {     public static void main(string[] args){         comparator<string> comparator = new stringlengthcomparator();         priorityqueue<string> queue = new priorityqueue<string>(10, comparator);         queue.offer("short");         queue.offer("abcahahahha");         queue.offer("lululu");         queue.stream().map( s-> {             system.out.println("queue: "+ s);             return s;         });     } } 

i have code , expect see "short", "lululu" , "abcahahahha" been printed out. don't see them. what's wrong code? compile fine. , using java 8 compiler , runtime.

the map() method intermediate , not enforce consumption of stream it's bad idea put side effects there.

in case, should use dedicated foreach() method:

queue.stream()   .foreach(s -> system.out.println("queue: " + s));