Arrays.copyOfRange() in Java with Examples

Arrays copyOfRange() method is used to create a new array by copying a specified range of elements from an existing array. It provides a way to copy a subset of elements between two indices by creating a new array of the same type.

Below is a simple example that uses Arrays.copyOfRange() method to copy a specified range of elements from an existing array.

Copied Array: [20, 30]

Syntax of Arrays.copyOfRange() method

public static int[] copyOfRange(int[] original_array, int from_index, int to_index)

Parameters:

• original_array : Array to be copied from.
• from_index : Starting index (inclusive) of range to be copied.
• to_end : The final index (exclusive) of the range to be copied.

Return Type:

• Returns a new array containing elements from the original array (length will be to_index to from_index).

Exceptions:

• ArrayIndexOutOfBoundsException : This is thrown if the initial index is out of range of original array.
• IllegalArgumentException : This is thrown if from_index > to_index.
• NullPointerException : This is thrown if the original array is null.

Examples of Arrays.copyOfRange() in Java

Now, let's understand the working of Arrays.copyOfRange() method with two examples.

Using Arrays.copyOfRange() with Integer Array

This method efficiently copies a specified range of elements from an array. This automatically handles out-of-range indices by filling missing elements with default values i.e. 0 for integers.

3 4 5 6 
5 6 7 0 0 0 

Using Arrays.copyOfRange() with Custom Objects

This method enables easy way to copy a subset of custom objects by reducing the need of manual iteration. This also supports type safety by specifying the target class type for object arrays.

40 geek4 50 geek5 
20 geek2 30 geek3 

copyOf vs copyOfRange

• copyOf(): This method copies elements starting from the 0th index of the original array, and we need to specify the new length of the array (number of elements to copy).
• copyOfRange(): This method copies a specific range of elements from the original array, defined by a start index (inclusive) and an end index (exclusive).