Method swap

Gfg/Java/wave_array.java:14–18

(int arr[], int i)

    }
    //swap alternate elements of array.
    public void swap(int arr[], int i){
        int temp = arr[i-1];
        arr[i-1] = arr[i];
        arr[i] = temp;
    }

    public static void main(String args[])
    {