Queue 인터페이스 추상 메서드 총 정리

Hierarchy of Java Collections

메서드	설명
import java.util.Queue;
boolean add(Object o)	지정된 객체를 Queue에 추가 저장공간 부족 시 IllegalStateException 발생
Object remove()	Queue에서 객체를 꺼내 반환 비어있을 경우 NoSuchElementException 발생
Object element()	삭제없이 요소를 읽어온다 비어있을 경우 NosuchElementException 발생
boolean offer(Object o)	Queue에 객체를 저장
Object poll()	Queue에서 객체를 꺼내서 반환 비어있을 경우 null을 반환
Object peek()	삭제없이 요소를 읽어온다 비어있을 경우 null을 반환

 

import java.util.Iterator;
import java.util.PriorityQueue;
import java.util.Queue;
 
/**
 * This class is used to show the PriorityQueue functionality.
 * @author w3schools
 */
public class PriorityQueueTest {
	public static void main(String args[]){
		Queue priorityQueue  = new PriorityQueue();
 
		priorityQueue.add("Gourav");
		priorityQueue.add("Neeraj");
		priorityQueue.add("Deepak");
		priorityQueue.add("Mohan");
		priorityQueue.add("Parmender");

		System.out.println("HasPriorityQueue elements:");
		System.out.println(priorityQueue);

		Iterator iterator1=priorityQueue.iterator();
		System.out.println("PriorityQueue elements " + "using iterator:");
        
		while(iterator1.hasNext()){  
		   System.out.println(iterator1.next());  
		}

		System.out.println("Head element: " + priorityQueue.element());
		System.out.println("Head element: " + priorityQueue.peek());

		priorityQueue.poll();
		priorityQueue.remove();

		System.out.println("HasPriorityQueue elements " + "after manipulation:");
		System.out.println(priorityQueue);

		Iterator iterator2=priorityQueue.iterator();
		System.out.println("PriorityQueue elements after " + "manipulation using iterator:");
        
		while(iterator2.hasNext()){  
		   System.out.println(iterator2.next());  
		}
	}
}

/*
HasPriorityQueue elements:
[Deepak, Mohan, Gourav, Neeraj, Parmender]
PriorityQueue elements using iterator:
Deepak
Mohan
Gourav
Neeraj
Parmender
Head element: Deepak
Head element: Deepak
HasPriorityQueue elements after manipulation:
[Mohan, Neeraj, Parmender]
PriorityQueue elements after manipulation using iterator:
Mohan
Neeraj
Parmender
*/