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Java DelayQueue offer()用法及代码示例


DelayQueue的offer()方法用于在延迟队列中插入指定的元素。它的作用类似于DelayQueue的add()方法。

用法:

public boolean offer (E e)

参数:
DelayQueue仅接受属于Delayed类型的那些元素。因此,此元素E的类型应为Delayed。


返回值:
此方法不返回任何内容。

异常:
NullPointerException :如果指定的元素为null。

下面的程序来说明Java中的DelayQueue offer():

例:

// Java Program Demonstrate DelayQueue offer() 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; 
  
    // Contructor 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<DelayObject> DQ 
            = new DelayQueue<DelayObject>(); 
  
        // Add numbers to end of DelayQueue 
        // using add() method 
        DQ.add(new DelayObject("A", 1)); 
        DQ.add(new DelayObject("B", 2)); 
  
        // Print delayqueue 
        System.out.println("Original DelayQueue: "
                           + DQ + "\n"); 
  
        // Now insert elements using offer method 
        DQ.offer(new DelayObject("C", 10)); 
        DQ.offer(new DelayObject("D", 11)); 
        DQ.offer(new DelayObject("E", 15)); 
        DQ.offer(new DelayObject("F", 17)); 
  
        // print queue 
        System.out.println("After insertion DelayQueue: "
                           + DQ); 
    } 
}
输出:
Original DelayQueue: [
{ A, time=1545817395066}, 
{ B, time=1545817395067}]

After insertion DelayQueue: [
{ A, time=1545817395066}, 
{ B, time=1545817395067}, 
{ C, time=1545817395076}, 
{ D, time=1545817395077}, 
{ E, time=1545817395081}, 
{ F, time=1545817395083}]


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注:本文由纯净天空筛选整理自ProgrammerAnvesh大神的英文原创作品 DelayQueue offer() method in Java with Examples。非经特殊声明,原始代码版权归原作者所有,本译文未经允许或授权,请勿转载或复制。