CopyOnWriteArrayList removeIf() method in Java with Examples

The removeIf() method of CopyOnWriteArrayList removes the element from this CopyOnWriteArrayList that satisfies the specified condition.

Syntax:

public boolean removeIf (Predicate<E> filter)

Parameters: This method accepts a mandatory parameter filter which is the predicate value based on which elements are removed from this List.

Return Value: This method returns a boolean value such as true, if the CopyOnWriteArrayList is changed. Else this method returns false.

Exceptions: This method throws NullPointerException if the specified Predicate filter is null.

Below program illustrates the removeIf() function of CopyOnWriteArrayList class :

// Java Program to illustrate the CopyOnWriteArrayList
// removeIf() 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(2);
        ArrLis.add(3);
        ArrLis.add(4);
        ArrLis.add(7);
        ArrLis.add(6);
        ArrLis.add(9);

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

        // if a number in the List is
        // divisible by 3, then remove it
        ArrLis.removeIf(number -> number % 3 == 0);

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

Output:

CopyOnWriteArrayList: [2, 3, 4, 7, 6, 9]
Updated CopyOnWriteArrayList: [2, 4, 7]

// Java Program to illustrate the CopyOnWriteArrayList
// removeIf() 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("GeeksforGeeks");
        ArrLis.add("GFG");
        ArrLis.add("Geeks");
        ArrLis.add("Gfg");

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

        try {

            // This will throw NullPointerException
            ArrLis.removeIf(null);
        }
        catch (Exception e) {
            System.out.println(e);
        }
    }
}

Output:

CopyOnWriteArrayList: [GeeksforGeeks, GFG, Geeks, Gfg]
java.lang.NullPointerException

Reference: https://docs.oracle.com/javase/9/docs/api/java/util/concurrent/CopyOnWriteArrayList.html#removeIf-java.util.function.Predicate-