What is Arrays.copyOf() method in Java?
Java class java.util.Arrays provides a method called Arrays.copyOf() that returns a copy of an array passed as a parameter to this function, followed by specifying its size. Here’s the method header for quick understanding.
Arrays.copyOf(int[] templateArray, int length);
Note that the second parameter “length” is the size of the copy array you want to create. So here we can have 3 cases.- The lengths of both template & copy arrays are the same.
- The length of the copy array is greater than the length of the template array.
- The length of the copy array is lesser than the length of the template array.

Coding Example
import java.util.Arrays;
public class ArraysCopyOfMethod {
public static void main(String[] args) {
// Initialize your templateArray which you want a copy of
int[] templateArray = new int[] {1, 2, 3, 4, 5, 6};
System.out.println("Template Array: " + Arrays.toString(templateArray));
// Create a "copy" of template array using
// Arrays.copyOf(int[] array, int arrayLength) method
// CASE 1: Sizes of both template & copy arrays are same
int[] copyArray1 = Arrays.copyOf(templateArray, templateArray.length);
System.out.println("Copy Array 1: " + Arrays.toString(copyArray1));
// CASE 2: Size of copy array > Size of template array
// extra space in copy array is filled with zeros
int[] copyArray2 = Arrays.copyOf(templateArray, 10);
System.out.println("Copy Array 2: " + Arrays.toString(copyArray2));
// CASE 3: Size of copy array < Size of template array
// copy array is only filled with only elements in overlapping size
int[] copyArray3 = Arrays.copyOf(templateArray, 3);
System.out.println("Copy Array 3: " + Arrays.toString(copyArray3));
}
}
Output
Template Array: [1, 2, 3, 4, 5, 6]
Copy Array 1: [1, 2, 3, 4, 5, 6]
Copy Array 2: [1, 2, 3, 4, 5, 6, 0, 0, 0, 0]
Copy Array 3: [1, 2, 3]
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