public class DemoBlockEntity extends BlockEntity {

    // 储存数字的当前值
    private int number = 7;
   
    public DemoBlockEntity(BlockPos pos, BlockState state) {
        super(TutorialBlockEntityTypes.DEMO_BLOCK, pos, state);
    }
   
    // 序列化方块实体
    @Override
    public void writeNbt(NbtCompound nbt, RegistryWrapper.WrapperLookup wrapper) {
        // 将数字的当前值保存到 nbt
        nbt.putInt("number", number);

        super.writeNbt(nbt, wrapper);
    }
}