Swap the first and last element of an array by creating a new array

Question

Why the value of Numbers[0] changes to 3 after executing the code line below?

New_Numbers [0] = Numbers [Numbers.length - 1];

The complete code:

public static void main(String[] args)
{

   System.out.print("Indique o número de elementos do array: ");
   int a = scanner.nextInt();
   int [] Numbers = new int [a];
   System.out.println("Indique os três elementos do array:");
   for ( int i = 0; i < a; i++ )
   {
       System.out.print("Número na posição " + i + " do array: ");
       Numbers [i] = scanner.nextInt();
   }
   int [] New_Numbers = Numbers;
   New_Numbers [0] = Numbers [Numbers.length - 1];
   New_Numbers [New_Numbers.length - 1] = Numbers [0];
   String Numbers_S = Arrays.toString(Numbers);
   String New_Numbers_S = Arrays.toString(New_Numbers);
   System.out.println("Array original: " + Numbers_S);
   System.out.println("Novo array após a troca entre o primeiro e o último elementos: " + New_Numbers_S);
}

Answer 1

In Java, when you assign an array to another array, as in this line:

int [] New_Numbers = Numbers;

You’re not creating a copy of the array, you’re just passing the same reference to another variable, so the two variables now point to the same array. So when you change the value of New_Numbers[0], is automatically changing the value of Numbers[0], because the two arrays are pointing to the same address in memory.

To make a copy of the array do so:

int[] New_Numbers = Arrays.copyOf(Numbers, Numbers.length);

Source:
problem with assigning an array to other array in java - Stack Overflow