java 方法示例_Java ArrayDeque offerFirst（）方法与示例

java 方法示例

ArrayDeque类offerFirst()方法 (ArrayDeque Class offerFirst() method)

offerFirst() Method is available in java.lang package.
offerFirst()方法在java.lang包中可用。
offerFirst() Method is used to add the given element at the front of this deque.
offerFirst()方法用于将给定元素添加到此双端队列的前面。
offerFirst() 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.
offerFirst()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。
offerFirst() Method may throw an exception at the time of adding element in the deque.
offerFirst()方法在双端队列中添加元素时可能会引发异常。

NullPointerException: This exception may throw when the given element is null exists.
NullPointerException ：当给定元素为null时，可能引发此异常。

Syntax:

句法：

    public boolean offerFirst(T element);

Parameter(s):

参数：

T element – represents the element to be inserted at the first position of this deque.
T element –表示要在此双端队列的第一个位置插入的元素。

Return value:

返回值：

The return type of the method is boolean, it returns true if the given element is added at the front of this deque successfully, else it returns false.

该方法的返回类型是布尔值，如果给定的元素在此双端队列的前面添加成功返回true，否则返回false。

Example:

例：

// Java program to demonstrate the example 
// of boolean offerFirst(T element) method of ArrayDeque 
import java.util.*;
public class OfferFirstOfArrayDeque {
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 offerFirst(): ");
System.out.println("ArrayDeque Elements = " + d_queue);
System.out.println();
// By using offerFirst() method to add the
// elements at the first position in ArrayDeque
d_queue.offerFirst("Python");
// Display Deque Elements
System.out.println("d_queue after offerFirst(): ");
System.out.println("d_queue.offerFirst() : "+ d_queue);
}
}

Output

输出量

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