List contains() method in Java with Examples

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

Syntax:

public boolean contains(Object obj)

object-element to be searched for

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.

Below programs illustrate the contains() method in List:

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

// 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 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

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

Reference: https://docs.oracle.com/javase/7/docs/api/java/util/List.html#contains(java.lang.Object)