June 9, 2024

Efficient Ways to Add Elements to an Array in Java

3 min read
how to add element in array in java


Arrays are fundamental data structures in Java, providing a convenient way to store and manipulate collections of similar elements. One common task in programming is adding elements to an array dynamically. In this article, we will explore various techniques to efficiently add elements to an array in Java. By understanding these methods, you can optimize your code and ensure better performance in scenarios where dynamic array modification is required.

Using ArrayList and toArray() Method 

Java’s ArrayList class is a dynamic array implementation that provides flexibility in adding and removing elements. To add elements to an existing array, you can convert it into an ArrayList, add elements to the ArrayList, and then convert it back to an array using the toArray() method.

Here’s an example


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String[] array = { “Apple”, “Banana”, “Orange” };

ArrayList<String> arrayList = new ArrayList<>(Arrays.asList(array));


array = arrayList.toArray(new String[0]);

In this approach, the existing array is converted to an ArrayList using the Arrays.asList() method. We add elements to the ArrayList using the add() method and convert it back to an array using the toArray() method. This technique allows for dynamic addition of elements to an array.

Using Arrays.copyOf() Method 

Java’s Arrays.copyOf() method allows you to create a new array with a specified length and copies elements from the original array into it. It is an efficient way to add elements to an array with a specific size.

Here’s an example


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String[] array = { “Apple”, “Banana”, “Orange” };

array = Arrays.copyOf(array, array.length + 1);

array[array.length – 1] = “Mango”;

In this approach, we use Arrays.copyOf() to create a new array with a length greater than the original array by one. Then, we assign the new element to the last index of the array. This method is useful when you need to add elements without using ArrayList.

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Using System.arraycopy() Method 

Java’s System.arraycopy() method allows you to efficiently copy elements from one array to another. By leveraging this method, you can add elements to an existing array at a specific index.

Here’s an example


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String[] array = { “Apple”, “Banana”, “Orange” };

String[] newArray = new String[array.length + 1];

int index = 1;

System.arraycopy(array, 0, newArray, 0, index);

newArray[index] = “Mango”;

System.arraycopy(array, index, newArray, index + 1, array.length – index);

array = newArray;

In this approach, we create a new array with a length greater than the original array by one. We copy the elements before the desired index using System.arraycopy(), insert the new element, and then copy the remaining elements after the index. Finally, we assign the new array to the original array.


How to use the add function in Java?

Overview. To add a specific element to a Set collection in Java, utilize the add() method of the Set class. If the supplied element is already existing in the set, the method returns false without adding the element. Otherwise, it adds the element.

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What is an array in Java?

An array is a container object that holds a fixed number of values of a single type. The length of an array is established when the array is created. After creation, its length is fixed. You have seen an example of arrays already, in the main method of the “Hello World!”


Adding elements to an array dynamically is a common requirement in Java programming. By utilizing techniques like converting to ArrayList and back to an array, using Arrays.copyOf(), or employing System.arraycopy(), you can efficiently add elements to an array in Java. Understanding these methods and their appropriate use cases will help you write more efficient and optimized code. Select the method that suits your specific scenario to ensure smooth array modification while maintaining code performance.

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