Java中的ConcurrentLinkedQueue contains()方法

ConcurrentLinkedQueue的 contains() 方法在参数中传入o对象时，会返回true，如果这个ConcurrentLinkedQueue中包含了至少一个等于传入o对象的元素e，也就是o.equals(e)。

语法：

public boolean contains(Object o)

参数： 这个方法需要传入一个单独的参数 O ，代表需要检查的对象，检验这个指定对象是否在ConcurrentLinkedQueue里。

返回值： 如果这个ConcurrentLinkedQueue里包含了这个对象，就返回true。

以下是ConcurrentLinkedQueue的contains()方法的演示程序：

例子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);
    }
}

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

例子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);
    }
}

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-