Java LinkedBlockingDeque offer()方法

LinkedBlockingDeque 的 offer(E e) 方法将参数中传递的元素插入到Deque的末端。如果容器的容量已经超过了，那么它不会像add()和addFirst()函数那样返回一个异常。

语法

public boolean offer(E e)

参数： 该方法接受一个强制参数 e ，它是要插入到LinkedBlockingDeque末端的元素。

返回： 如果元素已经被插入，该方法返回true，否则返回false。

下面的程序说明了LinkedBlockingDeque的offer()方法。

程序1 :

// Java Program Demonstrate offer()
// 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.offer(7855642);
        LBD.offer(35658786);
        LBD.offer(5278367);
        LBD.offer(74381793);
  
        // Cannot be inserted
        LBD.offer(10);
  
        // cannot be inserted hence returns false
        if (!LBD.offer(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 full
Linked Blocking Deque: [7855642, 35658786, 5278367, 74381793]

示例2

// Java Program Demonstrate offer()
// 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.offer("abc");
        LBD.offer("gopu");
        LBD.offer("geeks");
        LBD.offer("richik");
  
        // Cannot be inserted
        LBD.offer("hii");
  
        // cannot be inserted hence returns false
        if (!LBD.offer("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 full
Linked Blocking Deque: [abc, gopu, geeks, richik]

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