Java Collection remove() Method

The remove() method of Java Collection Interface is used to remove a single instance of the specified element from this collection.

Syntax

Parameters

The parameter 'o' represents the element to be removed from this collection if it is present.

Throws

ClassCastException- if the type of the specified element is not compatible with this collection

NullPointerException- if the specified element is null and this collection does not allow null elements

Returns

The remove() method returns a boolean value 'true' if the specified element is successfully removed as a result of this call.

Example 1

import java.util.Collection;
import java.util.HashSet;
public class JavaCollectionRemoveExample1 {
    public static void main(String[] args) {
        Collection<Integer> collection = new HashSet<>();
        collection.add(5);
        collection.add(15);
        collection.add(52);
        collection.add(532);
        collection.add(52);
        for (Integer i:collection) {
            System.out.println(i);
        }
       //will remove the specified element from the collection
        collection.remove(52);
        System.out.println("After removing 52 \nCollection : "+collection);
    }
}

Test it Now

Output:

52
532
5
15
After removing 52 
Collection : [532, 5, 15]

Example 2

import java.util.Collection;
import java.util.HashSet;
public class JavaCollectionRemoveExample2 {
    public static void main(String[] args) {
        Collection<String> collection = new HashSet<>();
        collection.add("Reema");
        collection.add("Geetanajli");
        collection.add("Mahesh");
        collection.add("Ajeet");

        for (String i:collection) {
            System.out.println(i);
        }
        //will remove the specified element from the collection
        boolean val=collection.remove("ABC");
        System.out.println("Remove method will return : "+val);
    }
}

Test it Now

Output:

Reema
Geetanajli
Mahesh
Ajeet
remove method will return : false

Example 3

import java.util.ArrayDeque;
import java.util.Collection;
public class JavaCollectionRemoveExample3 {
    public static void main(String[] args) {
        Collection<String> collection = new ArrayDeque<String>() {
        };
        collection.add("Reema");
        collection.add("Geetanajli");
        //pass an exception for null elements
        collection.add(null);

        for (String i:collection) {
            System.out.println(i);
        }
        //will remove the specified element from the collection
        boolean val=collection.remove("ABC");
        System.out.println("Remove method will return : "+val);
    }
}

Test it Now

Output:

Exception in thread "main" java.lang.NullPointerException
	at java.util.ArrayDeque.addLast(ArrayDeque.java:249)
	at java.util.ArrayDeque.add(ArrayDeque.java:423)
	at com.javaTpoint.JavaCollectionRemoveExample3.main(JavaCollectionRemoveExample3.java:13)

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