Java LinkedBlockingDeque takeFirst()方法

LinkedBlockingDeque 的 takeFirst() 方法返回并移除Deque容器中的第一个元素，如果有必要，可以等待，直到有元素可用。如果在等待过程中被打断，该方法会抛出一个InterruptedException。

语法

public E takeFirst()

返回： 该方法返回Deque容器的第一个元素，如果有必要，可以等待，直到有元素可用。

异常 ：如果在等待过程中被打断，该函数会抛出一个InterruptedException。

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

程序1 :

// Java Program to demonstrate takeFirst()
// method of LinkedBlockingDeque
  
import java.util.concurrent.LinkedBlockingDeque;
import java.util.*;
  
public class GFG {
    public static void main(String[] args)
        throws InterruptedException
    {
  
        // create object of LinkedBlockingDeque
        LinkedBlockingDeque<Integer> LBD
            = new LinkedBlockingDeque<Integer>();
  
        // Add numbers to end of LinkedBlockingDeque
        LBD.add(7855642);
        LBD.add(35658786);
        LBD.add(5278367);
        LBD.add(74381793);
  
        // print Dequeue
        System.out.println("Linked Blocking Deque: " + LBD);
  
        // removes the front element and prints it
        System.out.println("Head of Linked Blocking Deque: "
                           + LBD.takeFirst());
  
        // prints the Deque
        System.out.println("Linked Blocking Deque: " + LBD);
    }
}

输出:

Linked Blocking Deque: [7855642, 35658786, 5278367, 74381793]
Head of Linked Blocking Deque: 7855642
Linked Blocking Deque: [35658786, 5278367, 74381793]

程序2： 演示InterruptedException

// Java Program to demonstrate takeFirst()
// method of LinkedBlockingDeque
  
import java.util.concurrent.LinkedBlockingDeque;
import java.util.*;
  
public class GFG {
    public static void main(String[] args)
        throws InterruptedException
    {
  
        // create object of LinkedBlockingDeque
        LinkedBlockingDeque<Integer> LBD
            = new LinkedBlockingDeque<Integer>();
  
        // Add numbers to end of LinkedBlockingDeque
        LBD.add(7855642);
        LBD.add(35658786);
        LBD.add(5278367);
        LBD.add(74381793);
  
        // print Dequeue
        System.out.println("Linked Blocking Deque: " + LBD);
  
        LBD.clear();
  
        // throws error as the list is empty and it
        // is interrupted while waiting
        System.out.println("Head of Linked Blocking Deque: "
                           + LBD.takeFirst());
    }
}

运行时错误

Max real time limit exceeded due to either by heavy load on server or by using sleep function

参考资料: https://docs.oracle.com/javase/8/docs/api/java/util/concurrent/LinkedBlockingDeque.html#takeFirst-