Removing Element from the Specified Index in Java ArrayList

The remove(int index) method present in java.util.ArrayList class removes the element at the specified position in this list and shifts any subsequent elements to the left (i.e. subtracts one from their indices).

Syntax : 

public removed_element remove(int index)

Parameters: The index of the element to be removed.

Return Type: This method returns the element that was removed from the list.

Exception: This method throws IndexOutOfBoundsException if the index is out of range.

Java

// Java program to remove an element
// from an specified index from
// an ArrayList.

import java.util.ArrayList;

public class GFG {
    public static void main(String[] arg)
    {

        // creating an empty ArrayList with an initial
        // capacity of 5
        ArrayList<String> flower = new ArrayList<String>(5);

        // using add() method to add elements in the
        // ArrayList flower
        flower.add("red-rose");
        flower.add("tulip");
        flower.add("sun-flower");
        flower.add("marie-gold");
        flower.add("orchid");

        // printing the size of the ArrayList flower
        System.out.println("Size of list: "
                           + flower.size());

        // printing the ArrayList flower
        System.out.println("Flower ArrayList = " + flower);

        // Removing element at 3rd position from ArrayList
        // flower
        System.out.println(
            "Removing element at index = 2 ");
        flower.remove(2);

        System.out.println("After removing element");

        // printing the size of the ArrayList flower
        System.out.println("Size of list: "
                           + flower.size());

        // printing the ArrayList flower
        System.out.println("Flower ArrayList = " + flower);
    }
}

Output

Size of list: 5
Flower ArrayList = [red-rose, tulip, sun-flower, marie-gold, orchid]
Removing element at index = 2 
After removing element
Size of list: 4
Flower ArrayList = [red-rose, tulip, marie-gold, orchid]

Time Complexity: O(n)
Auxiliary Space: O(1)

As constant extra space is used.

When we will try to remove an element at the index which is greater than or equal to the size of the array list, the editor will give us the IndexOutOfBound Exception on running.

Java

// Java program to show the exception
// of remove() method

import java.util.ArrayList;

public class ArrayListDemo {
   public static void main(String[] args) {

      // create an empty array list with an initial capacity
      ArrayList<Integer> arrlist = new ArrayList<Integer>(5);

      // use add() method to add elements in the deque
      arrlist.add(20);
      arrlist.add(15);
      arrlist.add(30);
      arrlist.add(45);

      System.out.println("Size of list: " + arrlist.size());

      // let us print all the elements available in list
      for (Integer number : arrlist) {
         System.out.println("Number = " + number);
      }

      // Removes element at 5th position
      // which is not present in the list
      // and will therefore give IndexOutOfBound exception
      arrlist.remove(4);

      System.out.println("Now, Size of list: " + arrlist.size());

      // let us print all the elements available in list
      for (Integer number : arrlist) {
         System.out.println("Number = " + number);
      }
   }
}

Exception in thread "main" java.lang.IndexOutOfBoundsException: Index 4 out of bounds for length 4

Time Complexity: O(n)
Auxiliary Space: O(1)

As constant extra space is used.