Java ConcurrentLinkedDeque offerLast()方法

java.util.concurrent.ConcurrentLinkedDeque.offerLast()方法是Java中的一个内置方法，它将作为参数传递的指定元素插入到deque的末端。

语法

Conn_Linked_Deque.offerLast(Object elem)

参数： 该方法接受一个参数 elem ，它是要插入到deque末尾的元素的种类。

返回值： 如果元素被成功地添加到deque中，该函数返回True，否则返回False。

异常： 如果传递的参数是NULL，该函数会抛出一个NullPointerException。

以下程序说明了 ConcurrentLinkedDeque.offerLast() 方法。

程序1 :

/* Java Program to Demonstrate offerLast()
   method of ConcurrentLinkedDeque */
  
import java.util.concurrent.*;
class GFG {
    public static void main(String[] args)
    {
  
        // Creating an empty Deque
        ConcurrentLinkedDeque<String> cld = 
                       new ConcurrentLinkedDeque<String>();
  
        // Add elements into the Deque
        cld.add("Welcome");
        cld.add("To");
        cld.add("Geeks");
        cld.add("4");
        cld.add("Geeks");
  
        // Displaying the Deque
        System.out.println("Elements in Deque: "
                           + cld);
  
        // Displaying the Last element
        System.out.println("The Last element is: " + 
                                      cld.getLast());
  
        /* Insert an element at the tail
            of the deque */
        if (cld.offerLast("GFG")) {
            // Displaying the Last element
            System.out.println("The Inserted element is: " + 
                                              cld.getLast());
        }
  
        // Displaying the Deque
        System.out.println("Elements in Deque: "
                           + cld);
  
        // Displaying the Last element
        System.out.println("The Last element is: " + 
                                      cld.getLast());
    }
}

输出。

Elements in Deque: [Welcome, To, Geeks, 4, Geeks]
The Last element is: Geeks
The Inserted element is: GFG
Elements in Deque: [Welcome, To, Geeks, 4, Geeks, GFG]
The Last element is: GFG

代码2 :

/* Java Program to Demonstrate offerLast()
   method of ConcurrentLinkedDeque */
  
import java.util.concurrent.*;
class GFG {
    public static void main(String[] args)
    {
  
        // Creating an empty Deque
        ConcurrentLinkedDeque<Integer> cld = 
                  new ConcurrentLinkedDeque<Integer>();
  
        // Add elements into the Deque
        cld.add(12);
        cld.add(43);
        cld.add(29);
        cld.add(16);
        cld.add(70);
  
        // Displaying the Deque
        System.out.println("Elements in Deque: "
                           + cld);
  
        // Displaying the Last element
        System.out.println("The Last element is: " + 
                                      cld.getLast());
  
        try {
            cld.offerLast(null);
        }
        catch (Exception e) {
            System.out.println(e);
        }
  
        /* Insert an element at the tail
            of the deque */
        if (cld.offerLast(24)) {
            // Displaying the Last element
            System.out.println("The Inserted element is: "
                                          + cld.getLast());
        }
  
        // Displaying the Deque
        System.out.println("Elements in Deque: "
                           + cld);
  
        // Displaying the Last element
        System.out.println("The Last element is: " +
                                       cld.getLast());
    }
}

输出。

Elements in Deque: [12, 43, 29, 16, 70]
The Last element is: 70
java.lang.NullPointerException
The Inserted element is: 24
Elements in Deque: [12, 43, 29, 16, 70, 24]
The Last element is: 24

参考资料: https://docs.oracle.com/javase/8/docs/api/java/util/concurrent/ConcurrentLinkedDeque.html#offerLast()