How to remove an element from ArrayList in Java?

There are two way to remove an element from ArrayList.

1. By using remove() methods :
ArrayList provides two overloaded remove() method.
a. remove(int index) : Accept index of object to be removed.
b. remove(Obejct obj) : Accept object to be removed.

What happens when we have an integer arrayList and we want to remove an item? For example consider below program.

// Java program to demonstrate working of remove 
// on an integer arraylist 
import java.util.List; 
import java.util.ArrayList; 
  
public class GFG 
{ 
    public static void main(String[] args) 
    { 
        List<Integer> al = new ArrayList<>(); 
        al.add(10); 
        al.add(20); 
        al.add(30); 
        al.add(1); 
        al.add(2); 
  
        // This makes a call to remove(int) and  
        // removes element 20. 
        al.remove(1); 
          
        // Now element 30 is moved one position back 
        // So element 30 is removed this time 
        al.remove(1); 
  
        System.out.println("Modified ArrayList : " + al); 
    } 
} 

Output :

Modified ArrayList : [10, 1, 2]

We can see that the passed parameter is considered as index. How to remove elements by value.

// Java program to demonstrate working of remove 
// on an integer arraylist 
import java.util.List; 
import java.util.ArrayList; 
  
public class GFG 
{ 
    public static void main(String[] args) 
    { 
        List<Integer> al = new ArrayList<>(); 
        al.add(10); 
        al.add(20); 
        al.add(30); 
        al.add(1); 
        al.add(2); 
  
        // This makes a call to remove(Object) and  
        // removes element 1 
        al.remove(new Integer(1)); 
          
        // This makes a call to remove(Object) and  
        // removes element 2 
        al.remove(new Integer(2)); 
  
        System.out.println("Modified ArrayList : " + al); 
    } 
} 

/div>

Output :

Modified ArrayList : [10, 20, 30]

2. Using Iterator.remove() method :
It is not recommended to use ArrayList.remove() when iterating over elements. This may lead to ConcurrentModificationException (Refer this for a sample program with this exception). When iterating over elements, it is recommended to use Iterator.remove() method .

// Java program to demonstrate working of 
// Iterator.remove() on an integer arraylist 
import java.util.List; 
import java.util.ArrayList; 
import java.util.Iterator; 
  
public class GFG 
{ 
    public static void main(String[] args) 
    { 
        List<Integer> al = new ArrayList<>(); 
        al.add(10); 
        al.add(20); 
        al.add(30); 
        al.add(1); 
        al.add(2); 
  
        // Remove elements smaller than 10 using 
        // Iterator.remove() 
        Iterator itr = al.iterator(); 
        while (itr.hasNext()) 
        { 
            int x = (Integer)itr.next(); 
            if (x < 10) 
                itr.remove(); 
        } 
  
        System.out.println("Modified ArrayList : "
                                           + al); 
    } 
} 

Output :

Modified ArrayList : [10, 20, 30]

How to remove an element from ArrayList in Java?

tags:

You Might Also Like

leave a comment

0 Comments

Subscribe to Our Newsletter

Top Followed books