java 方法 示例

ArrayDeque类pollFirst()方法 (ArrayDeque Class pollFirst() method)

• pollFirst() Method is available in java.lang package.

  pollFirst()方法在java.lang包中可用。

• pollFirst() Method is used to return the first element of the queue denoted by this deque but with removing the first element from this deque.

  pollFirst()方法用于返回此双端队列表示的队列的第一个元素，但会从此双端队列中删除第一个元素。

• pollFirst() 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.

  pollFirst()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。

• pollFirst() Method does not throw an exception at the time retrieving element of this deque.

  pollFirst()方法在获取此双端队列的元素时不会引发异常。

Syntax:

句法：

public T pollFirst();

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 T, it returns the first element denoted by this deque otherwise it returns null, when this deque is "blank".

方法的返回类型为T ，它返回此双端队列表示的第一个元素，否则当此双端队列为“空白”时返回null。

Example:

例：

// Java program to demonstrate the example // of T pollFirst() method of ArrayDeque import java.util.*;public class PollFirstOfArrayDeque {
       public static void main(String[] args) {
           // Creating an ArrayDeque with initial capacity of        // storing elements        Deque < String > d_queue = new ArrayDeque < String > (10);        // By using add() method to add elements        // in ArrayDeque        d_queue.add("C");        d_queue.add("C++");        d_queue.add("Java");        d_queue.add("Php");        d_queue.add("DotNet");        // Display Deque Elements        System.out.println("d_queue before pollFirst(): ");        System.out.println("ArrayDeque Elements = " + d_queue);        System.out.println();        // By using pollFirst() method to remove and return the        // element at the first position in ArrayDeque        String ele = d_queue.pollFirst();        // Display Returned Elements        System.out.println("d_queue.pollFirst() : " + ele);        System.out.println();        // Display Deque Elements        System.out.println("d_queue after pollFirst(): ");        System.out.println("ArrayDeque Elements = " + d_queue);    }}

Output

输出量

d_queue before pollFirst(): ArrayDeque Elements = [C, C++, Java, Php, DotNet]d_queue.pollFirst() : Cd_queue after pollFirst(): ArrayDeque Elements = [C++, Java, Php, DotNet]

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java 方法 示例