Collections - Beginning Java 8 Language Features - page 553

Listing 12-19. Using a Deque as a FIFO Queue
// DequeAsQueue.java
package com.jdojo.collections;
import java.util.Deque;
import java.util.LinkedList;
import java.util.NoSuchElementException;
public class DequeAsQueue {
public static void main(String[] args) {
// Create a Deque and add elements at its tail using
// addLast() or offerLast() method
Deque<String> deque = new LinkedList<>();
deque.addLast("John");
deque.offerLast("Richard");
deque.offerLast("Donna");
deque.offerLast("Ken");
System.out.println("Deque: " + deque);
// Let's remove elements from the Deque until it is empty
while (deque.peekFirst() != null) {
System.out.println("Head Element: " + deque.peekFirst());
deque.removeFirst();
System.out.println("Removed one element from Deque");
System.out.println("Deque: " + deque);
}
// Now, the Deque is empty. Try to call its peekFirst(),
// getFirst(), pollFirst() and removeFirst() methods
System.out.println("deque.isEmpty(): " + deque.isEmpty());
System.out.println("deque.peekFirst(): " + deque.peekFirst());
System.out.println("deque.pollFirst(): " + deque.pollFirst());
try {
String str = deque.getFirst();
System.out.println("deque.getFirst(): " + str);
}
catch (NoSuchElementException e) {
System.out.println("deque.getFirst(): Deque is empty.");
}
try {
String str = deque.removeFirst();
System.out.println("deque.removeFirst(): " + str);
}
catch (NoSuchElementException e) {
System.out.println("deque.removeFirst(): Deque is empty.");
}
}
}