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The contains(E e) method of CopyOnWriteArrayList checks if a given element is present in the list or not. If the element atleast occurs one time, then the function returns true, else it returns false. Syntax:

public boolean contains(Object o)

Parameters: The function accepts a single mandatory parametero which specifies the element whose appearance is to be checked in the list. Return Value: The function returns true if the element is present atleast one time in the list, else it returns false. Below programs illustrate the above function: Program 1:

Java

// Java Program to illustrate the CopyOnWriteArrayList
// contains() method in Java
import java.util.concurrent.CopyOnWriteArrayList;
import java.util.*;

public class GFG {
    public static void main(String[] args)
    {

        // create object of CopyOnWriteArrayList
        CopyOnWriteArrayList<Integer> ArrLis
            = new CopyOnWriteArrayList<Integer>();

        // Add elements
        ArrLis.add(32);
        ArrLis.add(67);
        ArrLis.add(98);
        ArrLis.add(100);

        // print CopyOnWriteArrayList
        System.out.println("CopyOnWriteArrayList: " + ArrLis);

        // check using function
        if (ArrLis.contains(100))
            System.out.println("100 is present in the list");
        else
            System.out.println("100 is not present in the list");

        // check using function
        if (ArrLis.contains(20))
            System.out.println("20 is present in the list");
        else
            System.out.println("20 is not present in the list");
    }
}

Output:

CopyOnWriteArrayList: [32, 67, 98, 100]
100 is present in the list
20 is not present in the list

Program 2:

Java

// Java Program to illustrate the CopyOnWriteArrayList
// contains() method in Java
import java.util.concurrent.CopyOnWriteArrayList;
import java.util.*;

public class GFG {
    public static void main(String[] args)
    {

        // create object of CopyOnWriteArrayList
        CopyOnWriteArrayList<String> ArrLis
            = new CopyOnWriteArrayList<String>();

        // Add elements
        ArrLis.add("gopal");
        ArrLis.add("gfg");
        ArrLis.add("jgec");
        ArrLis.add("sudo");

        // print CopyOnWriteArrayList
        System.out.println("CopyOnWriteArrayList: " + ArrLis);

        // check using function
        if (ArrLis.contains("gfg"))
            System.out.println("'gfg' is present in the list");
        else
            System.out.println("'gfg' is not present in the list");

        // check using function
        if (ArrLis.contains("best"))
            System.out.println("'best' is present in the list");
        else
            System.out.println("'best' is not present in the list");
    }
}

Output:

CopyOnWriteArrayList: [gopal, gfg, jgec, sudo]
'gfg' is present in the list
'best' is not present in the list

Reference: https://docs.oracle.com/javase/8/docs/api/java/util/concurrent/CopyOnWriteArrayList.html#contains-E-

CopyOnWriteArrayList contains() method in Java

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