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Java ArrayDeque addFirst()用法及代码示例


Java中的java.util.ArrayDeque.addFirst(Object element)方法用于在此双端队列的前面插入特定元素。

用法:

Array_Deque.addFirst(Object element)

参数:参数element 的类型为ArrayDeque,表示要添加的元素。


返回值:该函数不返回任何值。

异常:如果传递的参数为NULL,则该方法将引发NullPointerException。

下面的程序演示了Java.util.ArrayDeque.addFirst()方法:
示例1:

// Java code to illustrate addFirst() 
import java.util.*; 
  
public class ArrayDequeDemo { 
    public static void main(String args[]) 
    { 
        // Creating an empty ArrayDeque 
        Deque<Integer> de_que = new ArrayDeque<Integer>(); 
  
        // Use add() method to add elements into the Deque 
        de_que.add(10); 
        de_que.add(15); 
        de_que.add(30); 
        de_que.add(20); 
        de_que.add(5); 
  
        // Displaying the ArrayDeque 
        System.out.println("ArrayDeque: " + de_que); 
  
        // Adding elements at front 
        de_que.addFirst(40); 
        de_que.addFirst(50); 
        de_que.addFirst(60); 
        de_que.addFirst(70); 
  
        // Displaying the ArrayDeque 
        System.out.println("ArrayDeque_front_addition: " + de_que); 
  
        // Adding elements using add() 
        de_que.add(1); 
        de_que.add(2); 
        de_que.add(3); 
  
        // Displaying the final ArrayDeque 
        System.out.println("Final ArrayDeque: " + de_que); 
    } 
}
输出:
ArrayDeque: [10, 15, 30, 20, 5]
ArrayDeque_front_addition: [70, 60, 50, 40, 10, 15, 30, 20, 5]
Final ArrayDeque: [70, 60, 50, 40, 10, 15, 30, 20, 5, 1, 2, 3]

示例2:

// Java code to illustrate addFirst() 
import java.util.*; 
  
public class ArrayDequeDemo { 
    public static void main(String args[]) 
    { 
        // Creating an empty ArrayDeque 
        Deque<String> de_que = new ArrayDeque<String>(); 
  
        // Use add() method to add elements into the Deque 
        de_que.add("Welcome"); 
        de_que.add("To"); 
        de_que.add("Geeks"); 
        de_que.add("4"); 
        de_que.add("Geeks"); 
  
        // Displaying the ArrayDeque 
        System.out.println("ArrayDeque: " + de_que); 
  
        // Adding elements at front 
        de_que.addFirst("GFG"); 
        de_que.addFirst("World"); 
        de_que.addFirst("Hello"); 
  
        // Displaying the ArrayDeque 
        System.out.println("ArrayDeque_front_addition: " + de_que); 
  
        // Adding elements using add() 
        de_que.add("Coding"); 
        de_que.add("At"); 
        de_que.add("BEST"); 
  
        // Displaying the final ArrayDeque 
        System.out.println("Final ArrayDeque: " + de_que); 
    } 
}
输出:
ArrayDeque: [Welcome, To, Geeks, 4, Geeks]
ArrayDeque_front_addition: [Hello, World, GFG, Welcome, To, Geeks, 4, Geeks]
Final ArrayDeque: [Hello, World, GFG, Welcome, To, Geeks, 4, Geeks, Coding, At, BEST]


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注:本文由纯净天空筛选整理自Chinmoy Lenka大神的英文原创作品 ArrayDeque addFirst() Method in Java。非经特殊声明,原始代码版权归原作者所有,本译文未经允许或授权,请勿转载或复制。