How to insert an object in an ArrayList at a specific position

java arraylist
Harshveer Singh picture Harshveer Singh · Aug 16, 2011 · Viewed 226.4k times · Source

Suppose I have an ArrayList of objects of size n. Now I want to insert an another object at specific position, let's say at index position k (is greater than 0 and less than n) and I want other objects at and after index position k to shift one index position ahead. So is there any way to do this directly in Java. Actually i want to keep the list sorted while adding new object.

Answer

CloudyMarble picture CloudyMarble · Aug 16, 2011

To insert value into ArrayList at particular index, use: 

public void add(int index, E element)

This method will shift the subsequent elements of the list. but you can not guarantee the List will remain sorted as the new Object you insert may sit on the wrong position according to the sorting order.

To replace the element at the specified position, use:

public E set(int index, E element)

This method replaces the element at the specified position in the list with the specified element, and returns the element previously at the specified position.

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