Reading and writing of structures to a file.

[brandon3055]

Im about to start working on a project that involves taking an in game structure and writing it to a file (including tile nbt data). Then reading that file and turning it back into an in game structure in much the same way the world edit plugin works. Given enough tile i can figure it all out myself but i am very new to file io with java so i am just wondering if anyone can point me to some good tutorials dealing with stuff like this.

[Draco18s]

http://minecraft.gamepedia.com/Schematic_file_format

[brandon3055]

http://minecraft.gamepedia.com/Schematic_file_format

Thanks that will be a massive help!

 

Im also interested in information about actually writing that data to a file however im sure thats just simple java stuff that i can figure out myself.

 

That won't cut it for 1.7 and onwards, as IDs are dynamically allocated per world.

I can probably just modify it to use the name instead of the id. Would be a larger file but im not too concerned about that.

 

Edit: or i could add a key that assigns the id of every type of block in the structure to the name of the block.

 

[Draco18s]

Yeah, FileIO is just regular java.  Real easy stuff.  Especially with the existence of the CompressedStreamTools (IIRC the class name).

 

I'm completely failing to locate the code snipped that helped me get started, unfortunately.

[brandon3055]

Yeah, FileIO is just regular java.  Real easy stuff.  Especially with the existence of the CompressedStreamTools (IIRC the class name).

 

I'm completely failing to locate the code snipped that helped me get started, unfortunately.

Thanks. I have just started researching file io. There are still some unknowns but from what iv got so far it looks simple enough.

 

My biggest concern when learning to do something like this is that i will learn how to do it one way. And there will be another easier and more efficient way that i missed.

 

Edit: You proved my point exactly! I was trying to figure out how to turn a structure into some sort of data format that i could read and write with FileInputStream and FileOutputStream. But with CompressedStreamTools it looks like i can just use an NBTCompound!

[Guest]

Ooh, io is something I really like in java. Anyway, you could use BrufferedWriters and BufferedReaders, as far as I know that is a vary efficient way. But to make it easier I would recommend using Json. Within minecraft, there is an api called Gson that can convert java objects to a Json file.

 

Here is some info/tutorials for the things mentioned above:

- Gson tutorial: http://www.mkyong.com/java/gson-streaming-to-read-and-write-json/

- BufferedWriters: http://www.mkyong.com/java/how-to-write-to-file-in-java-bufferedwriter-example/

- BufferedReaders: http://www.mkyong.com/java/how-to-read-file-from-java-bufferedreader-example/

 

Hope this helps, if there is any confusion about the tutorials listed just ask.

[brandon3055]

Thankyou for all your help! If it wasn't for all your help i would have spent hours messing with input and out put streams and who knows what else... But as it turns out this is going to be the easiest part of the hole project!

 

@Awesome_Spider I will keep those links and look at them later because im sure that will come in handy at some point. But i am in love with the idea of writing the structure to nbt because nbt is soo easy to use. So i think i will be going with CompressedStreamTools.

 

Unless i take a look at what you posted and like it even more... Actually now that i think about it being able to write an object to a file would probably be easier... Will have to take a good look at both before i decide for sure.

[Draco18s]

Edit: You proved my point exactly! I was trying to figure out how to turn a structure into some sort of data format that i could read and write with FileInputStream and FileOutputStream. But with CompressedStreamTools it looks like i can just use an NBTCompound!

 

A schematic file is just an .nbt with a different extension but with a known set of root-level keys.

[brandon3055]

Edit: You proved my point exactly! I was trying to figure out how to turn a structure into some sort of data format that i could read and write with FileInputStream and FileOutputStream. But with CompressedStreamTools it looks like i can just use an NBTCompound!

 

A schematic file is just an .nbt with a different extension but with a known set of root-level keys.

 

What i meant by that is i would have spent hours trying to make something that dose exactly what CompressedStreamTools dose.

 

So after looking at both methods i think i will be going with CompressedStreamTools because it looks easier to deal with then Gson.

[brandon3055]

One more question. I noticed in the Schematic file format the blocks are saved in an int array. But it occurred to me that the max value of a byte is 127 or 256 if you take advantage of the full range. However with mods block id's go much higher then that. Im just wondering if anyone knows how things like world edit get around that?

 

The only thing i can think of is to use an int array instead but im sure there is a better way because an int for each block would be very inefficient. Or is an int only as big as its value when saved to a file? Tested and now know that an int is infact bigger on disk then a byte even if it has the same value. Not that i think about it that was probably a stupid question.

[brandon3055]

Ok so im going to have to learn a bit about byte manipulation and do the same thing.

[brandon3055]

Well i dont care at all about schematics but i do care a little about the size of the file. 2 byte arrays would be half the size of an int array. But then again the schematics wont be that big anyway so in the long run it may not matter too much.

 

And on second thought i dont need to learn byte manipulation to use two bytes i can probably just use a math function. Now i wish i paid more attention in maths class lol.

 

Edit: I guess i did pay attention in math class!!

int value;

byte b1 = (byte)(value % 127);
byte b2 = (byte)(value / 127);

int result = (b2 * 127) + b1;

[brandon3055]

Yea.... Ok int array it is!

[TJones47]

On 2/20/2015 at 12:23 PM, Awesome_Spider said:

Ooh, io is something I really like in java. Anyway, you could use BrufferedWriters and BufferedReaders, as far as I know that is a vary efficient way. But to make it easier I would recommend using Json. Within minecraft, there is an api called Gson that can convert java objects to a Json file.

 

Here is some info/tutorials for the things mentioned above:

- Gson tutorial: http://www.mkyong.com/java/gson-streaming-to-read-and-write-json/

- BufferedWriters: http://www.mkyong.com/java/how-to-write-to-file-in-java-bufferedwriter-example/

- BufferedReaders: http://www.mkyong.com/java/how-to-read-file-from-java-bufferedreader-example/

 

Hope this helps, if there is any confusion about the tutorials listed just ask.

Thanks @Aewsome_Spider for the tutorials to BufferedReaders and Writers. I found a better tutorial for reading files in Java - goes over a lot more ways to read files and even tests which way is fastest. 

 

Java file reading tutorial: https://funnelgarden.com/java_read_file/