CreeperStructure class

public class CreeperStructure {

    public static void init(World world, int x, int y, int z) {
        world.setBlock(x, y, z, Blocks.emerald_block);
        world.setBlock(x, y + 1, z, Blocks.emerald_block);
        world.setBlock(x, y + 2, z, Blocks.emerald_block);

        world.setBlock(x, y + 3, z, Block.getBlockById(52));

        Entity entity;
        entity = new EntityCreeper(world);

        TileEntityMobSpawner tileentitymobspawner = (TileEntityMobSpawner)world.getTileEntity(x, y + 3, z);
        tileentitymobspawner.func_145881_a().func_98265_a(entity);
        NBTTagCompound nbt = new NBTTagCompound();
        tileentitymobspawner.writeToNBT(nbt);
        nbt.setShort("minSpawnDelay",(short)50);
        nbt.setShort("maxSpawnDelay",(short)200);
        tileentitymobspawner.readFromNBT(nbt);
    }
}