Java Collection contains() Method

The contains() method of Java Collection Interface returns a Boolean value 'true', if it contains the specified element in the collection.

Syntax

Parameters

The parameter 'o' represents the element whose occurrence in this collection is to be tested.

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 contains() method returns Boolean value 'true' if this collection contains all the specified element else it returns false.

Example 1

import java.util.ArrayDeque;
import java.util.Collection;
public class JavaCollectionContainsExample1 {
    static int i=1;
    public static void main(String[] args) {
        Collection<String> collection=new ArrayDeque<>();
        collection.add("Rama");
        collection.add("Sham");
        collection.add("Mira");
        collection.add("Rajesh");
        if(collection.contains("Rama")) {
            System.out.println("Rama is present");
        }
        else{
            System.out.println("Ram is absent");
        }
    }
}

Test it Now

Output:

Rama is present

Example 2

import java.util.Collection;
import java.util.Scanner;
import java.util.concurrent.ConcurrentLinkedQueue;
public class JavaCollectionContainsExample2 {
    public static void main(String[] args) {
        Scanner scanner=new Scanner(System.in);
        Collection<Integer> queue = new ConcurrentLinkedQueue<Integer>();
        queue.add(2);
        System.out.println("Q. Enter smallest even prime no");
        System.out.print("Ans ");int a = scanner.nextInt();
        if(queue.contains(a)) {
            System.out.println("Your answer is correct.");
        }
        else{
        System.out.println("Incorrect answer!");
        }
    }
}

Output:

Q. Enter smallest even prime no
Ans 2
Your answer is correct.

Example 3

import java.util.Collection;
import java.util.concurrent.ConcurrentLinkedQueue;
class Employee{
    public String name;
    static  String date;
    public Employee(String name, String date) {
        this.name = name;
        this.date = date;
    }
    public String toString(){
        return this.name+" is present on "+this.date;
    }
}
public class JavaCollectionContainsExample3 {
    public static void main(String[] args) {
    Collection<Employee> queue = new ConcurrentLinkedQueue<Employee>();
        Employee employee1=new Employee("Rahul","12.08.18");
        Employee employee2=new Employee("Geeta","12.08.18");
        Employee employee3=new Employee("Sham","12.08.18");
        Employee employee4=new Employee("Ravi","12.08.18");
        queue.add(employee1);
        queue.add(employee2);
        queue.add(employee3);
        queue.add(employee4);
        //will check if the queue contains this value or not
        if (queue.contains(employee3)){
            System.out.println(employee2);
        }
        else{
            System.out.println("This name is not in the list");
        }
    }
}

Test it Now

Output: