Arrays.copyOfRange() in Java with Examples

Last Updated : 11 Nov, 2024

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.

Java

import java.util.Arrays;

public class Main {
  
    public static void main(String[] args) {
      
        // Original array
        int[] arr1 = {10, 20, 30, 40,};

        // Copy elements from index 1 to 3 (exclusive)
        int[] arr2 = Arrays.copyOfRange(arr1, 1, 3);

        System.out.println("Copied Array: " + Arrays.toString(arr2));
    }
}

Output

Copied Array: [20, 30]

Table of Content

Syntax of Arrays.copyOfRange() method
Examples of Arrays.copyOfRange() in Java

Using Arrays.copyOfRange() with Integer Array
Using Arrays.copyOfRange() with Custom Objects

copyOf vs copyOfRange

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.

Java

// Java program to illustrate copyOfRange() method
import java.util.Arrays;

class GFG {

    public static void main(String args[]) {

        int arr1[] = { 1, 2, 3, 4, 5, 6, 7 };

        // Copying elements within range
        int[] arr2 = Arrays.copyOfRange(arr1, 2, 6);
        for (int i : arr2)
            System.out.print(i + "  ");

        System.out.println();

        // Copying with out-of-range index (fills with zeroes)
        int[] arr3 = Arrays.copyOfRange(arr1, 4, arr1.length + 3);
        for (int i : arr3)
            System.out.print(i + "  ");

        // Uncomment to see exceptions:
      
        // IllegalArgumentException
        // int[] arr4 = Arrays.copyOfRange(arr1, 5, 3);  
      
        // ArrayIndexOutOfBoundsException
        // int[] arr5 = Arrays.copyOfRange(arr1, 10, arr1.length + 5); 
    }
}

Output

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.

Java

// Java program to illustrate copyOfRange() method
import java.util.Arrays;

class GFG {
    
    static class Employee {
        int i;
        String n;

        // constructor
    public Employee(int i, String n)
        {
            this.i = i;
            this.n = n;
        }

        // Override toString()
    public String toString()
        {
            return i + "   " + n;
        }
    }

    public static void main(String args[]) {
        
      Employee[] e = {   new Employee(10, "geek1"),
                         new Employee(20, "geek2"),
                         new Employee(30, "geek3"),
                         new Employee(40, "geek4"),
                         new Employee(50, "geek5") };

        // Copying range from index 3 to 5 in E array
        Employee[] c = Arrays.copyOfRange(e, 3, 5);
        for (Employee e1 : c)
            System.out.print(e1.toString() + "  ");

        System.out.println();

        // Copying Employee array to Object array
        Object[] o = Arrays.copyOfRange(e, 1, 3, Object[].class);

        // Uncommenting the following line would throw an error
        // Number[] n = Arrays.copyOfRange(e, 1, 3, Number[].class);

        for (Object e1 : o) {
            System.out.print(e1.toString() + "  ");
        }
    }
}

Output

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).

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Sumit Ghosh

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Java

Arrays.copyOfRange() in Java with Examples

Syntax of Arrays.copyOfRange() method

Examples of Arrays.copyOfRange() in Java

Using Arrays.copyOfRange() with Integer Array

Using Arrays.copyOfRange() with Custom Objects

copyOf vs copyOfRange

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Using `Arrays.copyOfRange()` with Integer Array

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