Java ConcurrentLinkedQueue contains()方法

ConcurrentLinkedQueue 的 contains() 方法如果ConcurrentLinkedQueue包含作为参数传递的对象o，则返回true。只有当这个ConcurrentLinkedQueue包含至少一个与作为参数传递的对象o相等的元素e时，即o.equals(e)，该方法才返回true。

语法

public boolean contains(Object o)

参数： 该方法需要一个代表对象的参数 O ，用于检查ConcurrentLinkedQueue是否包含指定对象。

返回： 如果ConcurrentLinkedQueue包含该对象，该方法返回true。

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

例1 :

// Java Program Demonstrate contains()
// method of ConcurrentLinkedQueue
  
import java.util.concurrent.*;
  
public class GFG {
    public static void main(String[] args)
    {
  
        // create an ConcurrentLinkedQueue
        ConcurrentLinkedQueue<String>
            queue = new ConcurrentLinkedQueue<String>();
  
        // Add String to queue
        queue.add("Aman");
        queue.add("Amar");
        queue.add("Sanjeet");
        queue.add("Rabi");
  
        // Displaying the existing ConcurrentLinkedQueue
        System.out.println("ConcurrentLinkedQueue: " + queue);
  
        // check whether queue contains String "Aman"
        boolean response1 = queue.contains("Aman");
  
        // print after applying contains method
        System.out.println("queue contains String \"Aman\" : "
                           + response1);
  
        // check whether queue contains "Ram"
        boolean response2 = queue.contains("Ram");
  
        // print after applying contains method
        System.out.println("queue contains String \"Ram\" : "
                           + response2);
    }
}

输出。

ConcurrentLinkedQueue: [Aman, Amar, Sanjeet, Rabi]
queue contains String "Aman" : true
queue contains String "Ram" : false

例2 :

// Java Program Demonstrate contains()
// method of ConcurrentLinkedQueue
  
import java.util.concurrent.*;
  
public class GFG {
    public static void main(String[] args)
    {
  
        // create an ConcurrentLinkedQueue
        ConcurrentLinkedQueue<Integer>
            queue = new ConcurrentLinkedQueue<Integer>();
  
        // Add Numbers to queue
        queue.add(4353);
        queue.add(7824);
        queue.add(78249);
        queue.add(8724);
  
        // Displaying the existing ConcurrentLinkedQueue
        System.out.println("ConcurrentLinkedQueue: " + queue);
  
        // check whether queue contains 78249
        boolean response1 = queue.contains(78249);
  
        // print after applying contains method
        System.out.println("queue contains Number 78249 : "
                           + response1);
  
        // check whether queue contains 9876
        boolean response2 = queue.contains(9876);
  
        // print after applying contains method
        System.out.println("queue contains Number 9876: "
                           + response2);
    }
}

输出。

ConcurrentLinkedQueue: [4353, 7824, 78249, 8724]
queue contains Number 78249 : true
queue contains Number 9876: false

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