Java中的 DelayQueue take() 方法及示例

DelayQueue 的take()方法用于检索 DelayQueue 的头部，并将其删除。因此，DelayQueue 的大小减小了。如果此队列中存在具有过期延迟的元素，此函数将等待。
句法：

public E take ()

参数：此方法不接受任何参数。
返回值：函数返回DelayQueue的头部。
异常：如果在等待时被中断，此方法将抛出InterruptedException 。
下面的程序说明了 DelayQueue.take() 方法：
程序：

Java

// Java Program Demonstrate DelayQueue take() method
 
import java.util.concurrent.*;
import java.util.*;
 
// The DelayObject for DelayQueue
// It must implement Delayed and
// its getDelay() and compareTo() method
class DelayObject implements Delayed {
 
    private String name;
    private long time;
 
    // Constructor of DelayObject
    public DelayObject(String name, long delayTime)
    {
        this.name = name;
        this.time = System.currentTimeMillis()
                    + delayTime;
    }
 
    // Implementing getDelay() method of Delayed
    @Override
    public long getDelay(TimeUnit unit)
    {
        long diff = time - System.currentTimeMillis();
        return unit.convert(diff, TimeUnit.MILLISECONDS);
    }
 
    // Implementing compareTo() method of Delayed
    @Override
    public int compareTo(Delayed obj)
    {
        if (this.time < ((DelayObject)obj).time) {
            return -1;
        }
        if (this.time > ((DelayObject)obj).time) {
            return 1;
        }
        return 0;
    }
 
    // Implementing toString() method of Delayed
    @Override
    public String toString()
    {
        return "\n{"
            + " " + name + ", time=" + time + "}";
    }
}
 
// Driver Class
public class GFG {
    public static void main(String[] args) throws InterruptedException
    {
 
        // create object of DelayQueue
        // using DelayQueue() constructor
        BlockingQueue DQ
            = new DelayQueue();
 
        // Add numbers to end of DelayQueue
        // using add() method
        DQ.add(new DelayObject("A", 1));
        DQ.add(new DelayObject("B", 2));
        DQ.add(new DelayObject("C", 3));
        DQ.add(new DelayObject("D", 4));
 
        // print the size of DelayQueue
        System.out.println("Size of the DelayQueue: "
                           + DQ.size());
        // print queue
        System.out.println("DelayQueue: "
                           + DQ);
 
        // take() function will retrieve and remove the head of DelayQueue
        System.out.println("Head of the DelayQueue:"
                           + DQ.take());
        // print the size of DelayQueue
        System.out.println("Size of the DelayQueue: "
                           + DQ.size());
        // print queue
        System.out.println("DelayQueue: "
                           + DQ);
    }
}

输出：

Size of the DelayQueue: 4
DelayQueue: [
{ A, time=1546842594283}, 
{ B, time=1546842594284}, 
{ C, time=1546842594285}, 
{ D, time=1546842594286}]
Head of the DelayQueue:
{ A, time=1546842594283}
Size of the DelayQueue: 3
DelayQueue: [
{ B, time=1546842594284}, 
{ D, time=1546842594286}, 
{ C, time=1546842594285}]