public void moveZeroes(int[] nums) {
    int len = 0;

    for(int i = 0; i < nums.length; i++){
        if (nums[i] != 0){
            swap(nums, len, i);
            len++;
        }
    }
}

private void swap(int[] nums, int left, int right) {
    int temp = nums[left];
    nums[left] = nums[right];
    nums[right]= temp;
}