Hello!
I need to save the building and the coordinates of the required blocks.

For example, this is how the building looks like. And the block coordinate that I need to save looks like this.

 

I use this code to get building blocks. The first and second blocks are redstone blocks that are located at the edges of the building.

        int maxY = firstBlockXYZ[1];
        int firstBlockX = firstBlockXYZ[0];
        int firstBlockZ = firstBlockXYZ[2];
        int secondBlockX = secondBlockXYZ[0];
        int secondBlockZ = secondBlockXYZ[2];

        List<String> blocks = new ArrayList<>();

        for(int x=firstBlockX; x>=secondBlockX; x--) {
            for(int z=firstBlockZ; z>=secondBlockZ; z--) {
                BlockPos blockPos = new BlockPos(x, maxY, z);
                Block block = world.getBlockState(blockPos).getBlock();
                blocks.add(String.valueOf(block));
            }
        }

 

Further, to get the coordinates of the necessary blocks, I manually take the coordinates of the necessary blocks and subtract these coordinates from the first redstone block.

 

Finally, I save the list of blocks and the required coordinates to a json file.

{
  "name": "building",
  "blocks": [
    "Block{minecraft:redstone_block}",
    "Block{minecraft:stone}",
    ...
  ],
  "coordinates": [
    "-11 -7 -6",
    "XXX",
    "XXX"
  ]
}

 

This works great for one degree. If need to rotate the building, it won't work.

I somehow need to change the block indices in the json file and, accordingly, change the coordinates of the necessary blocks.

Maybe I should change the format for saving blocks and necessary blocks from a json file to a schematic file? But, I have never used the schematic and do not understand it.

Structure blocks are your friend here. I suggest using them to generate what you are looking for.