Block in mca ( MC Anvil map ) editing in Java

Question

for my personal project I need to edit every the bytes of every section in a chunk that is stored in a .mca file. I can already generate the bytes that I need for the blocks. The only problem I have is that I can't understand how to edit these type of files very easily in java.

Answer 1

Here is an example using this Java NBT library, it provides instructions on including to your project in the README. Hope this helps!

byte[][][] generatedBytes = new byte[16][256][16];
MCAFile mcaFile = new MCAFile(0, 0);
Chunk chunk = Chunk.newChunk();

// Generate bytes to be put into chunk, here we just generate some stripes
for (int y=0; y < 256; y++) {
    for (int z = 0; z < 16; z++) {
        for (int x = 0; x < 16; x++) {
            generatedBytes[x][y][z] = (byte) (x % 3);
        }
    }
}

// Write our generated bytes to a chunk
for (int y=0; y < 256; y++) {
    for (int z = 0; z < 16; z++) {
        for (int x = 0; x < 16; x++) {
            CompoundTag blockTag = new CompoundTag();
            String blockType = "minecraft:air";

            switch (generatedBytes[x][y][z]) {
                case 1:
                    blockType = "minecraft:stone";
                    break;
                case 2:
                    blockType = "minecraft:grass_block";
                    break;
                default:
                    break;
            }

            blockTag.putString("Name", blockType);

            chunk.setBlockStateAt(x, y, z, blockTag, false);
        }
    }
}

mcaFile.setChunk(0, 0, chunk);
MCAUtil.write(mcaFile, "r.0.0.mca");