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List contains() method in Java with Examples
  • Last Updated : 11 Dec, 2018

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)

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