Java中的LinkedBlockingDeque offerFirst（）方法-yiteyi-C++库

这个 报价第一（E） 方法 LinkedBlockingDeque 在Deque容器的前面插入传入参数的元素。如果容器的容量已超过，那么它不会像add（）和addFirst（）函数那样返回异常。

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语法：

public boolean offerFirst(E e)

参数： 此方法接受一个强制参数 E 这是要插入到LinkedBlockingDeque前面的元素。

返回： 此方法返回 符合事实的 如果元素已插入，则返回 错误的

下面的程序演示了LinkedBlockingDeque的offerFirst（）方法：

项目1：

JAVA

                         // Java Program Demonstrate offerFirst()                       
                         // method of LinkedBlockingDeque                       
           
                         import                                     java.util.concurrent.LinkedBlockingDeque;                       
                         import                                     java.util.*;                       
           
                         public                                     class                                     GFG {                       
                                                 public                                     static                                     void                                     main(String[] args)                       
                                                 throws                                     IllegalStateException                       
                                                 {                       
           
                                                 // create object of LinkedBlockingDeque                       
                                                 LinkedBlockingDeque<Integer> LBD                       
                                                 =                                     new                                     LinkedBlockingDeque<Integer>(                                     4                                     );                       
           
                                                 // Add numbers to end of LinkedBlockingDeque                       
                                                 LBD.offerFirst(                                     7855642                                     );                       
                                                 LBD.offerFirst(                                     35658786                                     );                       
                                                 LBD.offerFirst(                                     5278367                                     );                       
                                                 LBD.offerFirst(                                     74381793                                     );                       
           
                                                 // Cannot be inserted                       
                                                 LBD.offerFirst(                                     10                                     );                       
           
                                                 // cannot be inserted hence returns false                       
                                                 if                                     (!LBD.offerFirst(                                     10                                     ))                       
                                                 System.out.println(                                     "The element 10 cannot be inserted"                                     +                       
                                                 " as capacity is full"                                     );                       
           
                                                 // before removing print queue                       
                                                 System.out.println(                                     "Linked Blocking Deque: "                                     + LBD);                       
                                                 }                       
                         }                       

输出：

The element 10 cannot be inserted as capacity is fullLinked Blocking Deque: [74381793, 5278367, 35658786, 7855642]

项目2：

JAVA

                         // Java Program Demonstrate offerFirst()                       
                         // method of LinkedBlockingDeque                       
           
                         import                                     java.util.concurrent.LinkedBlockingDeque;                       
                         import                                     java.util.*;                       
           
                         public                                     class                                     GFG {                       
                                                 public                                     static                                     void                                     main(String[] args)                       
                                                 throws                                     IllegalStateException                       
                                                 {                       
           
                                                 // create object of LinkedBlockingDeque                       
                                                 LinkedBlockingDeque<String> LBD                       
                                                 =                                     new                                     LinkedBlockingDeque<String>(                                     4                                     );                       
           
                                                 // Add numbers to end of LinkedBlockingDeque                       
                                                 LBD.offerFirst(                                     "abc"                                     );                       
                                                 LBD.offerFirst(                                     "gopu"                                     );                       
                                                 LBD.offerFirst(                                     "geeks"                                     );                       
                                                 LBD.offerFirst(                                     "richik"                                     );                       
           
                                                 // Cannot be inserted                       
                                                 LBD.offerFirst(                                     "hii"                                     );                       
           
                                                 // cannot be inserted hence returns false                       
                                                 if                                     (!LBD.offerFirst(                                     "hii"                                     ))                       
                                                 System.out.println(                                     "The element 'hii' cannot be"                       
                                                 +                                     " inserted as capacity is full"                                     );                       
           
                                                 // before removing print queue                       
                                                 System.out.println(                                     "Linked Blocking Deque: "                                     + LBD);                       
                                                 }                       
                         }                       

输出：

The element 'hii' cannot be inserted as capacity is fullLinked Blocking Deque: [richik, geeks, gopu, abc]

参考： https://docs.oracle.com/javase/7/docs/api/java/util/concurrent/LinkedBlockingDeque.html#offerFirst（E）

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