PriorityQueue類poll()方法 (PriorityQueue Class poll() method)

• poll() method is available in java.util package.

  poll()方法在java.util包中可用。

• poll() method is used to return the first element with removing an element from this PriorityQueue.

  poll()方法用于返回第一個元素，并從此PriorityQueue中刪除一個元素。

• poll() method is a non-static method, it is accessible with the class object only and if we try to access the method with the class name then we will get an error.

  poll()方法是一種非靜態方法，只能通過類對象訪問，如果嘗試使用類名稱訪問該方法，則會收到錯誤消息。

• poll() method does not throw an exception at the time of returning an element.

  poll()方法在返回元素時不會引發異常。

Syntax:

句法：

    public Element poll();

Parameter(s):

參數：

• It does not accept any parameter.

  它不接受任何參數。

Return value:

返回值：

The return type of the method is Element, it returns the head element from this PriorityQueue when exists otherwise it returns null.

方法的返回類型為Element ，如果存在，它將從此PriorityQueue返回head元素，否則返回null。

Example:

例：

// Java program to demonstrate the example 
// of Element poll() method of 
// PriorityQueue
import java.util.*;
public class PollOfPriorityQueue {
public static void main(String args[]) {
// Instantiate PriorityQueue
PriorityQueue < String > pq = new PriorityQueue < String > ();
// By using add() method is add
// the given element into priority
// queue
pq.add("C");
pq.add("C++");
pq.add("JAVA");
pq.add("PHP");
pq.add("ANDROID");
// Display PriorityQueue
System.out.println("PriorityQueue: " + pq);
// By using poll() method is to
// return and remove the first element
// from this PriorityQueue
Object ele = pq.poll();
// Display poll element
System.out.println("pq.poll(): " + ele);
// Display PriorityQueue
System.out.println("PriorityQueue: " + pq);
}
}

Output

輸出量

PriorityQueue: [ANDROID, C, JAVA, PHP, C++]
pq.poll(): ANDROID
PriorityQueue: [C, C++, JAVA, PHP]

翻譯自: https://www.includehelp.com/java/priorityqueue-poll-method-with-example.aspx