PriorityQueue类的peek()方法 (PriorityQueue Class peek() method)

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

  peek()方法在java.util包中可用。

• peek() method is used to return the first element without removing an element from this PriorityQueue.

  peek()方法用于返回第一个元素，而不从此PriorityQueue中删除一个元素。

• peek() 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.

  peek()方法是一种非静态方法，只能通过类对象访问，如果尝试使用类名称访问该方法，则会收到错误消息。

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

  peek()方法在返回元素时不会引发异常。

Syntax:

句法：

public Element peek();

Parameter(s):

参数：

• It does not accept any parameter.

  它不接受任何参数。

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.

方法的返回类型为Element ，如果存在，它将从此PriorityQueue返回head元素，否则返回null。

Example:

例：

// Java program to demonstrate the example // of Element peek() method of // PriorityQueueimport java.util.*;public class PeekOfPriorityQueue {
       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 peek() method is to        // return the first or head element        // from this PriorityQueue        Object ele = pq.peek();        // Display peek element        System.out.println("pq.peek(): " + ele);    }}

Output

输出量

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

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