In the world of programming, there are often times when we encounter problems that require creative solutions. One such problem that many Java developers have faced is the limitation of the add method in the ArrayList class. This method is used to add elements to an ArrayList, but what happens when we want to add an element at a specific index? This is where the concept of "overriding" comes into play.
So, what exactly is overriding? In simple terms, it is the process of providing a new implementation for a method that is already defined in a parent class. In this case, we will be overriding the add method in the ArrayList class to provide a solution to the problem of adding elements at a specific index.
To begin, let's take a look at the structure of the add method in the ArrayList class:
public void add(int index, E element)
As we can see, this method takes in two parameters - the index at which the element is to be added, and the element itself. However, there is no way to specify the index when using this method. This is where our overridden method will come in.
First, we need to create a new class that extends the ArrayList class. Let's call it IndexedArrayList. Next, we will define a new add method in this class with the same signature as the one in the ArrayList class. However, our implementation will be slightly different:
public void add(int index, E element) {
super.add(index, element);
for (int i = index + 1; i < super.size(); i++) {
super.add(i, super.get(i - 1));
super.remove(i - 1);
}
}
Let's break this down. The first line calls the add method of the parent class, passing in the index and element as parameters. This will add the element at the specified index, but it will also shift all the elements after that index to the next index. This is where the for loop comes in. It starts from the index after the one we specified and moves each element one index forward. This effectively places the element at the desired index and shifts all the other elements accordingly.
But wait, what about the element that was originally at the specified index? Well, we don't want to lose that element, so we use the remove method to remove it from the index it was shifted to, which is why we use the index - 1.
Let's see this in action with an example:
IndexedArrayList list = new IndexedArrayList();
list.add(0, "Hello");
list.add(1, "World");
list.add(1, "Java");
The result of this would be an ArrayList with the elements "Hello", "Java", "World". As you can see, the element "Java" was successfully added at index 1, without overwriting the element "World".
In conclusion, by overriding the add method in the ArrayList class, we have provided a solution to the problem of adding elements at a specific index. This is just one example of how overriding can be used to overcome limitations and enhance functionality in programming. So the next time you encounter a problem, remember that there is always a solution waiting to be discovered through the power of overriding.
