Java中的 DelayQueue put() 方法及示例

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

语法：

public void put(E ele)

参数：此方法只接受一个参数ele 。它将被插入延迟队列中的元素。
返回值：方法的返回类型为void，不返回任何值。
例外：

• NullPointerException ：如果给定值为 null，则抛出该异常。

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

Java

// 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 queue = new DelayQueue();
 
        // 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());
    }
}

输出：

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

程序 2 ：NullPointerException 的演示。

Java

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

输出：

java.lang.NullPointerException

参考：https: Java/util/concurrent/DelayQueue.html#put(E)