Java PriorityBlockingQueue clear()方法

PriorityBlockingQueue的 clear() 方法会移除这个队列中的所有元素。因此，当需要清除PriorityBlockingQueue的时候，可以应用这个方法。

语法

public void clear()

参数：

此方法不需要任何参数。

返回：

此方法不返回任何东西。

异常:

此方法不抛出任何异常。

下面的程序说明了使用clear()方法从PriorityBlockingQueue中删除所有的元素。

例1 :

// Java Program to Demonstrate clear() method
// of PriorityBlockingQueue.
  
import java.util.concurrent.PriorityBlockingQueue;
  
public class GFG {
  
    public static void main(String[] args)
    {
        // define capacity of PriorityBlockingQueue
        int capacity = 15;
  
        // create object of PriorityBlockingQueue
        PriorityBlockingQueue<Integer> PrioBlockingQueue
            = new PriorityBlockingQueue<Integer>(capacity);
  
        // add numbers
        PrioBlockingQueue.add(78758575);
        PrioBlockingQueue.add(63447688);
        PrioBlockingQueue.add(56434788);
  
        // print queue after add operation
        System.out.println("After Adding  Numbers:");
        System.out.println("PriorityBlockingQueue:"
                           + PrioBlockingQueue);
  
        // remove all the elements using clear() method
        PrioBlockingQueue.clear();
  
        // print queue after clear operation
        System.out.println("\nAfter clear operation:");
        System.out.println("PriorityBlockingQueue:"
                           + PrioBlockingQueue);
    }
}

输出:

After Adding  Numbers:
PriorityBlockingQueue:[56434788, 78758575, 63447688]

After clear operation:
PriorityBlockingQueue:[]

例2： 在一个包含名字列表的PriorityBlockingQueue上说明清晰的方法。

// Java Program to Demonstrate clear() method
// of PriorityBlockingQueue.
  
import java.util.concurrent.PriorityBlockingQueue;
  
public class GFG {
  
    public static void main(String[] args)
    {
        // define capacity of PriorityBlockingQueue
        int capacity = 15;
  
        // create object of PriorityBlockingQueue
        PriorityBlockingQueue<String> PrioBlockingQueue
            = new PriorityBlockingQueue<String>(capacity);
  
        // add some names
        PrioBlockingQueue.add("Tandrima");
        PrioBlockingQueue.add("Argha");
        PrioBlockingQueue.add("Arka");
  
        // print queue after add operation
        System.out.println("List of Names:");
        System.out.println("PriorityBlockingQueue: "
                           + PrioBlockingQueue);
  
        // remove all the elements using clear() method
        PrioBlockingQueue.clear();
  
        // print queue after clear operation
        System.out.println("\nAfter clearing List of names:");
        System.out.println("PriorityBlockingQueue:"
                           + PrioBlockingQueue);
    }
}

输出:

List of Names:
PriorityBlockingQueue: [Argha, Tandrima, Arka]

After clearing List of names:
PriorityBlockingQueue:[]

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