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