Java 中的 DelayQueue put()方法，示例

原文:https://www . geeksforgeeks . org/delay queue-put-method-in-Java-with-examples/

Java 中 DelayQueue 类的 put(E ele)方法用于将给定的元素插入延迟队列容器中。E 是这个延迟队列容器维护的元素类型。

语法:

public void put(E ele)

参数:该方法只接受一个参数元素。它是将被插入延迟队列的元素。 返回值:该方法的返回类型为 void，不返回值。 异常:

  • NullPointRexception:如果给定值为空，则抛出。

下面的程序说明了 Java 中 DelayQueue 的 put()方法: 程序 1 :

Java 语言(一种计算机语言，尤用于创建网站)

// Java program to illustrate the put()
// method in Java

import java.util.concurrent.DelayQueue;
import java.util.concurrent.Delayed;
import java.util.concurrent.TimeUnit;

public class GFG {
    public static void main(String args[])
    {
        // Create DelayQueue instance
        DelayQueue<Delayed> queue = new DelayQueue<Delayed>();

        // Initially Delay Queue is empty
        System.out.println("Before calling put() : "
                           + queue.isEmpty());

        // Create an object of type Delayed
        Delayed ele = new Delayed() {
            public long getDelay(TimeUnit unit)
            {
                return 24; // some value is returned
            }

            public int compareTo(Delayed o)
            {
                if (o.getDelay(TimeUnit.DAYS) >
                              this.getDelay(TimeUnit.DAYS))
                    return 1;
                else if (o.getDelay(TimeUnit.DAYS) == 
                                this.getDelay(TimeUnit.DAYS))
                    return 0;
                return -1;
            }
        };

        // Insert the created object to DelayQueue
        // using the put() method
        queue.put(ele);

        // Check if DelayQueue is empty.
        System.out.println("After calling put() : "
                           + queue.isEmpty());
    }
}

Output: 

Before calling put() : true
After calling put() : false

程序 2:NullPointerException 的演示。

Java 语言(一种计算机语言，尤用于创建网站)

// Java program to illustrate the Exception thrown
// by put() method of DelayQueue

import java.util.concurrent.DelayQueue;
import java.util.concurrent.Delayed;
import java.util.concurrent.TimeUnit;

public class GFG {
    public static void main(String args[])
    {
        DelayQueue<Delayed> queue = new DelayQueue<Delayed>();

        try {
            queue.put(null);
        }
        catch (Exception e) {
            System.out.println(e);
        }
    }
}

Output: 

java.lang.NullPointerException

参考:https://docs . Oracle . com/javase/7/docs/API/Java/util/concurrent/delayqueue . html # put(E)

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