Copy Java Array and make a duplicate of it

Question

I have an array x which is constantly being updated. Lets say a = [1,4,9,16,25]. I want to make an exact duplicate copy of x and call it y

Answer 1

Java Array Copy Methods

Object.clone(): Object class provides clone() and as we know, an array in java is also an Object, we can use this method to achieve full array copy. Note: This method will not suit you if you want partial copy of the array.

Arrays.copyOfRange(): If only few elements of an array are to be copied, where starting index is not 0, you may use this method to copy partial array.

System.arraycopy(): System class arraycopy() is the best way to do partial copy of an array. It provides you an easy way to specify the total number of elements to copy and the source and destination array index positions. For example

 System.arraycopy(source, 3, destination, 2, 8) 

will copy 8 elements from source to destination, beginning from 3rd index of source to 2nd index of destination

Arrays.copyOf(): If you want to copy first few elements of an array or full copy of array, you can use this method. It is used due to its simplcity

Answer 2

You can use System.arraycopy().

int[] src  = new int[]{1,2,3,4,5};
int[] dest = new int[5];
System.arraycopy( src, 0, dest, 0, src.length );

Answer 3

int[] a = {1,2,3,4,5};
int[] b = Arrays.copyOf(a, a.length);
int[] c = a.clone();

//What if array a comes as local parameter? You need to use null check:

public void someMethod(int[] a) {
    if (a!=null) {
        int[] b = Arrays.copyOf(a, a.length);
        int[] c = a.clone();
    }
}