Java中的PriorityBlockingQueue contains()方法

contains(Object o) 方法检查PriorityBlockingQueue是否包含对象o。如果队列包含至少一个元素e，它等于作为参数传递的对象o，即e.equals(o)，此方法返回true。如果队列不包含对象o，则方法返回false。

语法：

public boolean contains(Object o)

参数： 此方法采用一个强制性参数o，该参数为要在PriorityBlockingQueue中检查的对象。

返回值： 如果此队列包含作为参数传递的对象，则此方法返回true。否则它返回false。

异常： 此方法不会抛出任何异常。

下面的程序说明了PriorityBlockingQueue的contains()方法：

示例1：

//Java程序演示PriorityBlockingQueue的contains(Object o)方法
  
import java.util.concurrent.PriorityBlockingQueue;
  
public class GFG {
  
    public static void main(String[] args)
    {
        //定义PriorityBlockingQueue的容量
        int capacityOfQueue = 5;
  
        //创建PriorityBlockingQueue对象
        PriorityBlockingQueuePrioQueue
            = new PriorityBlockingQueue(capacityOfQueue);
  
        //向PriorityBlockingQueue添加元素
        PrioQueue.add(4641515);
        PrioQueue.add(46514561);
        PrioQueue.add(56156);
        PrioQueue.add(948964165);
  
        //打印PrioQueue
        System.out.println("PrioQueue："+PrioQueue);
  
        //检查PriorityBlockingQueue是否包含56156
        boolean answer1 = PrioQueue.contains(56156);
  
        //打印结果
        System.out.println("PriorityBlockingQueue contains "
                           + "number 56156 : "
                           + answer1);
  
        //检查PriorityBlockingQueue 是否包含46545
        boolean answer2 = PrioQueue.contains(46545);
  
        //打印结果
        System.out.println("PriorityBlockingQueue contains"
                           + " number 46545 : "
                           + answer2);
    }
}

PrioQueue：[56156,46514561,4641515,948964165]
PriorityBlockingQueue contains number 56156 : true
PriorityBlockingQueue contains number 46545 : false

示例2： 演示包含名称列表的PriorityBlockingQueue的contains()方法。

// Java Program Demonstrate contains(Object o)
// method of PriorityBlockingQueue

import java.util.concurrent.PriorityBlockingQueue;

public class GFG {

    public static void main(String[] args)
    {
        // define capacity of PriorityBlockingQueue
        int capacityOfQueue = 10;

        // create object of PriorityBlockingQueue
        PriorityBlockingQueue<String> names
            = new PriorityBlockingQueue<String>(capacityOfQueue);

        // Add names
        names.add("Geeks");
        names.add("forGeeks");
        names.add("A");
        names.add("Computer");
        names.add("Portal");

        // print queue details
        System.out.println("List of Names: " + names);

        // check whether PriorityBlockingQueue contains Geeks
        boolean answer1 = names.contains("Geeks");

        // print result
        System.out.println("Does names contains "
                                   + "Geeks: "
                                   + answer1);

        // check whether PriorityBlockingQueue contains SandeepJain
        boolean answer2 = names.contains("SandeepJain");

        // print result
        System.out.println("Does names contains "
                                   + "SandeepJain: "
                                   + answer2);
    }
}

List of Names: [A, Computer, Geeks, forGeeks, Portal]
Does names contains Geeks: true
Does names contains SandeepJain: false

参考：
https://docs.oracle.com/javase/8/docs/api/java/util/concurrent/PriorityBlockingQueue.html#contains-java.lang.Object-