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Arraylist.contains() in Java

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In Java, ArrayList contains() method in Java is used for checking if the specified element exists in the given list or not. 

 Syntax of Java ArrayList contains() :

public boolean contains(Object)
object-element to be searched for

Parameters: object- element whose presence in this list is to be tested 

Returns: It returns true if the specified element is found in the list else it returns false.

Java ArrayList contains() examples

Example 1: Demonstrate the working of the method contains() in an integer.

Java

// Java code to demonstrate the working of
// contains() method in ArrayList
 
// for ArrayList functions
import java.util.ArrayList;
 
class GFG {
    public static void main(String[] args)
    {
 
        // creating an Empty Integer ArrayList
        ArrayList<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

Example 2: Demonstrate the working of the method contains() in the string 

Java

// Java code to demonstrate the working of
// contains() method in ArrayList of string
 
// for ArrayList functions
import java.util.ArrayList;
 
class GFG {
    public static void main(String[] args)
    {
 
        // creating an Empty String ArrayList
        ArrayList<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. 

Note: Time Complexity is O(n)

Reference: Oracle Docs



Last Updated : 07 May, 2023
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