public void update()

in Minecraft/src/main/java/com/microsoft/Malmo/MissionHandlers/MovingTargetDecoratorImplementation.java [117:214]
88 lines of code
22 McCabe index (conditional complexity)

    public void update(World world)
    {
        if (this.mustWaitTurn && !this.isOurTurn)   // Using the turn scheduler?
            return;
        if (!this.mustWaitTurn)
        {
            // Not using turn scheduler - using update speed
            this.timeSinceLastUpdate++;
            if (this.timeSinceLastUpdate < this.speedInTicks)
                return;
        }
        this.timeSinceLastUpdate = 0;
        this.isOurTurn = false; // We're taking it right now.
        if (!pinchedByPlayer(world))
        {
            BlockPos posHead = this.path.peekFirst();
            BlockPos posTail = this.path.peekLast();
            // For now, only move in 2D - can make this more flexible later.
            ArrayList<BlockPos> possibleMovesForward = new ArrayList<BlockPos>();
            ArrayList<BlockPos> possibleMovesBackward = new ArrayList<BlockPos>();
            for (int x = -1; x <= 1; x++)
            {
                for (int z = -1; z <= 1; z++)
                {
                    if (z != 0 && x != 0)
                        continue;   // No diagonal moves.
                    if (z == 0 && x == 0)
                        continue;   // Don't allow no-op.
                    // Check this is a valid move...
                    BlockPos candidateHeadPos = new BlockPos(posHead.getX() + x, posHead.getY(), posHead.getZ() + z);
                    BlockPos candidateTailPos = new BlockPos(posTail.getX() + x, posTail.getY(), posTail.getZ() + z);
                    if (isValid(world, candidateHeadPos))
                        possibleMovesForward.add(candidateHeadPos);
                    if (isValid(world, candidateTailPos))
                        possibleMovesBackward.add(candidateTailPos);
                }
            }
            // Choose whether to move the "head" or the "tail"
            ArrayList<BlockPos> candidates = null;
            boolean forwards = true;
            if (possibleMovesBackward.isEmpty())
            {
                candidates = possibleMovesForward;
                forwards = true;
            }
            else if (possibleMovesForward.isEmpty())
            {
                candidates = possibleMovesBackward;
                forwards = false;
            }
            else
            {
                forwards = this.rng.nextDouble() < 0.5;
                candidates = forwards ? possibleMovesForward : possibleMovesBackward;
            }
            if (!candidates.isEmpty())
            {
                BlockDrawingHelper drawContext = new BlockDrawingHelper();
                drawContext.beginDrawing(world);
    
                BlockPos newPos = candidates.get(this.rng.nextInt(candidates.size()));
                if (forwards)
                {
                    // Add the new head:
                    this.originalPath.addFirst(world.getBlockState(newPos));
                    drawContext.setBlockState(world, newPos, this.blockType);
                    this.path.addFirst(newPos);
                    // Move the tail?
                    if (this.path.size() > this.pathSize)
                    {
                        drawContext.setBlockState(world, posTail, new XMLBlockState(this.originalPath.removeLast()));
                        this.path.removeLast();
                    }
                }
                else
                {
                    // Backwards - add the new tail:
                    this.originalPath.addLast(world.getBlockState(newPos));
                    drawContext.setBlockState(world, newPos, this.blockType);
                    this.path.addLast(newPos);
                    // Move the head?
                    if (this.path.size() > this.pathSize)
                    {
                        drawContext.setBlockState(world, posHead, new XMLBlockState(this.originalPath.removeFirst()));
                        this.path.removeFirst();
                    }
                }
                drawContext.endDrawing(world);
            }
        }
        if (this.mustWaitTurn)
        {
            // Let server know we have finished.
            Map<String, String> data = new HashMap<String, String>();
            data.put("agentname", this.guid);
            MalmoMod.network.sendToServer(new MalmoMod.MalmoMessage(MalmoMessageType.CLIENT_TURN_TAKEN, 0, data));
        }
    }