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List contains() method in Java with Examples

Last Updated : 03 Dec, 2024

The contains() method of List interface in Java is used for checking if the specified element exists in the given list or not.

Example:

Java


 // Java Program to Demonstrate
// List contains() Method
import java.util.*;

class GFG 
{
    public static void main (String[] args) 
    {
      	List<Integer> l = new ArrayList<>();
      
      	l.add(1);
      	l.add(2);
      
      	// Cheking List contains 2
      	System.out.println("List contains 2 : " + l.contains(2));
      	
      	// Cheking List contains 3
      	System.out.println("List contains 3 : " + l.contains(3));
    }
}

Output

List contains 2 : true
List contains 3 : false

Syntax of Method

public boolean contains(Object obj)

Parameters: This method accepts a single parameter obj whose presence in this list is to be tested.
Return Value: It returns true if the specified element is found in the list else it returns false.

Practical Application : In search operations, we can check if a given element exists in a list or not.

Example of List contains() Method

Below programs illustrate the contains() method in List:

Program 1: Demonstrate the working of the method contains() in List of integer.

Java


 // Java code to demonstrate the working of
// contains() method in List interface

import java.util.*;

class GFG {
    public static void main(String[] args)
    {
        // creating an Empty Integer List
        List<Integer> arr = new ArrayList<Integer>(4);

        // using add() to initialize values
        // [1, 2, 3, 4]
        arr.add(1);
        arr.add(2);
        arr.add(3);
        arr.add(4);

        // use contains() to check if the element
        // 2 exits or not
        boolean ans = arr.contains(2);

        if (ans)
            System.out.println("The list contains 2");
        else
            System.out.println("The list does not contains 2");

        // use contains() to check if the element
        // 5 exits or not
        ans = arr.contains(5);

        if (ans)
            System.out.println("The list contains 5");
        else
            System.out.println("The list does not contains 5");
    }
}

Output

The list contains 2
The list does not contains 5

Program 2: Demonstrate the working of the method contains() in List of string.

Java


 // Java code to demonstrate the working of
// contains() method in List of string

import java.util.*;

class GFG {
    public static void main(String[] args)
    {
        // creating an Empty String List
        List<String> arr = new ArrayList<String>(4);

        // using add() to initialize values
        // ["geeks", "for", "geeks"]
        arr.add("geeks");
        arr.add("for");
        arr.add("geeks");

        // use contains() to check if the element
        // "geeks" exits or not
        boolean ans = arr.contains("geeks");

        if (ans)
            System.out.println("The list contains geeks");
        else
            System.out.println("The list does not contains geeks");

        // use contains() to check if the element
        // "coding" exits or not
        ans = arr.contains("coding");

        if (ans)
            System.out.println("The list contains coding");
        else
            System.out.println("The list does not contains coding");
    }
}

Output

The list contains geeks
The list does not contains coding

Reference: Click here to check the official document

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