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.

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// 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);
    }
}

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Output : 


Modified ArrayList : [10, 1, 2]


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











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// 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); 


    } 


} 



















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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 .











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// 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); 


    } 


} 



















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Output : 


Modified ArrayList : [10, 20, 30]


This article is contributed by Nitsdheerendra. If you like GeeksforGeeks and would like to contribute, you can also write an article using contribute.geeksforgeeks.org or mail your article to contribute@geeksforgeeks.org. See your article appearing on the GeeksforGeeks main page and help other Geeks.



          
          
          
          

            

    

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