Examples below show how to remove element from a ArrayList

There are various ways of removing an item from a ArrayList type in Java as explained below.

1) Remove element from ArrayList using Java 8

Java 8 provides removeIf(Predicate) method in Collection interface that takes Predicate as an argument and it removes all the entries in the ArrayList which match the given Predicate. In below example users.removeIf(u -> u.equals("Harry")); removes the String "Harry" from the ArrayList.

import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;

// Removes element from a ArrayList    
public class MyClass {
    public static void main(String[] args) {
        List<String> users = new ArrayList<String>();
        users.add("Harry");
        users.add("IronMan");
        users.add("Batman");
        
        users.removeIf(u -> u.equals("Harry"));
        
        System.out.println("users " + users);
    }
}	

Output :

users [IronMan, Batman]		

2) Remove element from ArrayList while iterating using Iterator remove()

While looping over an ArrayList, it is recommended to use Iterator remove() for removing an element from ArrayList as you will not get ConcurrentModificationException. If the underlying ArrayList is modified while removing the element, then the results are not predictable.

import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;

// Removes element from a List    
public class MyClass {
    public static void main(String[] args) {
        List<String> users = new ArrayList<String>();
        users.add("Harry");
        users.add("IronMan");
        users.add("Batman");
        
        Iterator<String> itr = users.iterator();
        
        while (itr.hasNext()) {
            String user = itr.next();
            if (user.equalsIgnoreCase("Harry")) {
               itr.remove(); // Remove entry from ArrayList
            }
        }
		
        System.out.println("users " + users);
    }
}	

Output :

users [IronMan, Batman]		

import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;

// Removes element from a List    
public class MyClass {
    public static void main(String[] args) {
        List<String> users = new ArrayList<String>();
        users.add("Harry");
        users.add("IronMan");
        users.add("Batman");
        
        for (String user : users) {
            if (user.equalsIgnoreCase("Harry")) {
                users.remove(user);
            }
        }
		
        System.out.println("users " + users);
    }
}	

Output :

Exception in thread "main" java.util.ConcurrentModificationException
	at java.util.ArrayList$Itr.checkForComodification(Unknown Source)
	at java.util.ArrayList$Itr.next(Unknown Source)
	at MyClass.main(MyClass.java:12)		

3) Using List remove(int index)

You can remove element from ArrayList by using List remove(int index) method. It will use the index at which the element is stored in the ArrayList to remove the element. Below example shows how to remove entry from List using List remove(int index) method.

import java.util.ArrayList;
import java.util.List;

// Removes entry from ArrayList	using remove()
public class MyClass {
    public static void main(String[] args) {
        List<String> celebrities = new ArrayList<String>();
        celebrities.add("Harry");
        celebrities.add("IronMan");
        celebrities.add("Batman");
        celebrities.remove(1); // Remove entry from ArrayList
		
        System.out.println("celebrities " + celebrities);
    }
}	

Output :

celebrities [Harry, Batman]	

4) Using List remove(Object object)

You can remove element from ArrayList by using List remove(Object object) method. It checks the existence of element by using: Object equals() and removes the first element that matches the element in ArrayList.
Below example shows how to remove entry from List using List remove(Object object) method.

import java.util.ArrayList;
import java.util.List;

// Removes element from ArrayList using List remove(Object object)		
public class MyClass {
    public static void main(String[] args) {
        List<String> celebrities = new ArrayList<String>();
        celebrities.add("Harry");
        celebrities.add("IronMan");
        celebrities.add("Batman");
        celebrities.remove("Harry"); // Remove entry from ArrayList
        celebrities.forEach(System.out::println);
    }
}	

Output :

IronMan
Batman		

5) Remove all elements from ArrayList using List removeAll()

You can remove all elements from ArrayList by using List removeAll() method. It removes all of the elements from the ArrayList. List removeAll() has time complexity of O(N^2)Below example shows how to remove all the elements from a List using List removeAll() method.

import java.util.ArrayList;
import java.util.List;

// Remove all elements from ArrayList    
public class MyClass {
    public static void main(String[] args) {
        List<String> users = new ArrayList<String>();
        users.add("Harry");
        users.add("IronMan");
        users.add("Batman");
        
        users.removeAll(users);
		
        System.out.println("users " + users);
    }
}	

Output :

users []		

6) Remove all elements from ArrayList using List clear()

You can remove element from ArrayList by using List clear() method. It removes all of the elements from the list . The list will be empty after this call returns. List clear() has time complexity of O(N). Below example shows how to remove all the elements from a ArrayList using List clear() method.

import java.util.ArrayList;
import java.util.List;

// Remove all elements from ArrayList    
public class MyClass {
    public static void main(String[] args) {
        List<String> users = new ArrayList<String>();
        users.add("Harry");
        users.add("IronMan");
        users.add("Batman");
        
        users.clear();
		
        System.out.println("users " + users);
    }
}
	

Output :

users []