Java PriorityBlockingQueue contains()方法

contains(Object o) 方法检查PriorityBlockingQueue是否包含一个对象o。该方法返回真，当且仅当该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)。如果队列不包含对象o，那么方法返回false。

语法

public boolean contains(Object o)

参数： 该方法需要一个强制参数o，它是要在PriorityBlockingQueue中检查的对象。

返回： 如果该队列包含作为参数传递的对象，该方法返回 true 。否则，它返回 false。

异常： 此方法不抛出任何异常。

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

例1 :

// 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 = 5;
  
        // create object of PriorityBlockingQueue
        PriorityBlockingQueue<Integer> PrioQueue
            = new PriorityBlockingQueue<Integer>(capacityOfQueue);
  
        // Add element to PriorityBlockingQueue
        PrioQueue.add(4641515);
        PrioQueue.add(46514561);
        PrioQueue.add(56156);
        PrioQueue.add(948964165);
  
        // print PrioQueue
        System.out.println("PrioQueue: " + PrioQueue);
  
        // check whether PriorityBlockingQueue contains 56156
        boolean answer1 = PrioQueue.contains(56156);
  
        // print result
        System.out.println("PriorityBlockingQueue contains "
                           + "number 56156 : "
                           + answer1);
  
        // check whether PriorityBlockingQueue contains 46545
        boolean answer2 = PrioQueue.contains(46545);
  
        // print result
        System.out.println("PriorityBlockingQueue contains"
                           + " number 46545 : "
                           + answer2);
    }
}

输出:

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

例2： 演示PriorityBlockingQueue的contains()方法，该方法包含名字列表。

// 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);
    }
}

输出:

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

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