How to Check whether Element Exists in Java ArrayList?
Last Updated :
18 Jul, 2022
Java ArrayList is a resizable array, which can be found in java.util package. We can add or delete elements from an ArrayList whenever we want, unlike a built-in array.
We can check whether an element exists in ArrayList in java in two ways:
- Using contains() method
- Using indexOf() method
Method 1: Using contains() method
The contains() method of the java.util.ArrayList class can be used to check whether an element exists in Java ArrayList.
Syntax:
public boolean contains(Object)
Parameter:
- 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
import java.io.*;
import java.util.ArrayList;
class GFG {
public static void main(String[] args)
{
ArrayList<Integer> list = new ArrayList<>();
list.add( 1 );
list.add( 2 );
list.add( 3 );
list.add( 4 );
if (list.contains( 5 ))
System.out.println( "5 exists in the ArrayList" );
else
System.out.println( "5 does not exist in the ArrayList" );
if (list.contains( 2 ))
System.out.println( "2 exists in the ArrayList" );
else
System.out.println( "2 does not exist in the ArrayList" );
}
}
|
Output
5 does not exist in the ArrayList
2 exists in the ArrayList
Method 2: Using indexOf() method
- Contains() method uses indexOf() method to determine if a specified element is present in the list or not.
- So we can also directly use the indexOf() method to check the existence of any supplied element value.
Java
import java.io.*;
import java.util.ArrayList;
class GFG {
public static void main (String[] args) {
ArrayList<Integer> list = new ArrayList<>();
list.add( 2 );
list.add( 5 );
list.add( 1 );
list.add( 6 );
if (list.indexOf( 5 )>= 0 )
System.out.println( "5 exists in the ArrayList" );
else
System.out.println( "5 does not exist in the ArrayList" );
if (list.indexOf( 8 )>= 0 )
System.out.println( "8 exists in the ArrayList" );
else
System.out.println( "8 does not exist in the ArrayList" );
}
}
|
Output
5 exists in the ArrayList
8 does not exist in the ArrayList
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