Explanation about what's wrong.

Question

//Output should swap 2 positions, I can't explain myself why this code doesn't function.

class ArrayTools
{
public static void main(String[] args)
{
int[] array = {1,2,3,4,5};
//Test
int[] swap = swap(array,2,4);
for (int i=0; i<swap.length; i++)
System.out.print(swap[i]);
}

public static int[] swap(int[] a, int i1, int i2)
{
int[] swap = new int[];
for (int i=0; i<a.length; i++)
{
if(swap[i] == a[i1])
swap[i] = a[i2];
else if(swap[i] == a[i2])
swap[i] = a[i1];
else
swap[i] = a[i];
}

return swap;
}
//OUTPUT: 12345
}

/*
Here is a code that is functioning well but I think it's not effcient to write it first and replace it right after it, so the CPU have to declare it 2 times instead of once.:

swap[i] = a[i];
if(swap[i] == a[i1])
swap[i] = a[i2];
else if(swap[i] == a[i2])
swap[i] = a[i1];

//OUTPUT: 12543
*/

Answer 1

This doesn't explain my Question actually..