Thanks
Fixed:
@Override
public ActionResult<ItemStack> use(World world, PlayerEntity player, Hand hand) {
Block block = Blocks.SAND;
double xcoord = player.getX();
double ycoord = player.getY();
double zcoord = player.getZ();
BlockPos blockPos = new BlockPos(xcoord, ycoord, zcoord);
world.setBlockAndUpdate(blockPos, block.defaultBlockState());
return super.use(world, player, hand);
}