public class DemoBlock extends BlockWithEntity {
    [...]
    @Override
    protected ItemActionResult onUseWithItem(ItemStack stack, BlockState state, World world, BlockPos pos, PlayerEntity player, Hand hand, BlockHitResult hit) {
        ...
        if (!player.getStackInHand(hand).isEmpty()) {
            ...
        } else {
            // 如果玩家手中没有东西，就依次给玩家方块实体中的物品

            // 找到第一个有物品的槽位，并给玩家
            if (!blockEntity.getStack(1).isEmpty()) {
                // 给玩家物品栏中的物品堆
                player.getInventory().offerOrDrop(blockEntity.getStack(1));
                // 从物品栏移除物品堆
                blockEntity.removeStack(1);
            } else if (!blockEntity.getStack(0).isEmpty()) {
                player.getInventory().offerOrDrop(blockEntity.getStack(0));
                blockEntity.removeStack(0);
            } else {
                return ItemActionResult.PASS_TO_DEFAULT_BLOCK_INTERACTION;
            }
        }
        
        return ItemActionResult.SUCCESS;
    }
}