I've got a custom machine (a two-input, one output "machine") that I cobbled together out of a tutorial series, starting with this video:

 

I managed to get everything working (even better than the tutorial demonstrated), and I had the machine's recipes working on a list-based system, which was functional, but ugly. I wanted to make it a bit more elegant, so I copied over the vanilla furnace's recipe system and changed it around a bit so that it would accept ArrayLists instead of ItemStacks as the key for the HashMap that the recipes are stored in. It no longer works, and will crash the game when attempting to cook any valid recipes. I don't know if the Vanilla FurnaceRecipes class has anything special done to make it work properly OUTSIDE of that class, but I have a feeling that there's something like that.

 

I'd link you to GitHub for this, as these classes already have tons of code, but I don't actually have that set up yet.

 

 

Recipe "Handler" Class

package com.exo594.tutorial;

import com.exo594.tutorial.item.ModItems;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;
import net.minecraft.block.Block;
import net.minecraft.init.Blocks;
import net.minecraft.init.Items;
import net.minecraft.item.Item;
import net.minecraft.item.ItemStack;


public final class IngotMasherRecipes {

    public static final IngotMasherRecipes mashingBase = new IngotMasherRecipes();

    private static Map mashingList = new HashMap();
    ArrayList<ItemStack> addingKeyList = new ArrayList<ItemStack>();
    
    private static final Item[] ITEMS = new Item[]{Items.bread, ModItems.tutorialItem};
    
    
    //ArrayList<ItemStack> addingValueList = new ArrayList<ItemStack>();

    public static IngotMasherRecipes mashing() {
        return mashingBase;
    }

    private IngotMasherRecipes() {
        this.addMashingRecipeWithTwoItems(ModItems.tutorialItem, Items.bread, new ItemStack(ModItems.tutoriumLoaf));
        this.addMashingRecipeWithTwoItems(Items.iron_ingot, ModItems.tutorialItem, new ItemStack(ModItems.craftingPendulum));
        this.addMashingRecipeWithOneBlock(Blocks.glowstone, Items.diamond, new ItemStack(ModItems.tutoriumGrenade, 1));
    }

    //used to tell transferItemInStack to play nice with items, apparantly not quite working properly
    public static Boolean itemCanBeMashed(ItemStack itemstack) {
        if (Arrays.asList(ITEMS).contains(itemstack.getItem())) {
            return true;
        } else {
            return false;
        }
    }

    public void addMashingRecipeWithOneBlock(Block blockIn, Item itemIn, ItemStack itemOut) {
        this.addMashingRecipeWithTwoItems(Item.getItemFromBlock(blockIn), itemIn, itemOut);
    }

    public void addMashingRecipeWithTwoBlocks(Block blockOneIn, Block blockTwoIn, ItemStack itemOut) {
        this.addMashingRecipeWithTwoItems(Item.getItemFromBlock(blockOneIn), Item.getItemFromBlock(blockTwoIn), itemOut);
    }

    public void addMashingRecipeWithTwoItems(Item itemOneIn, Item itemTwoIn, ItemStack itemOut) {
        this.addRecipeFinal(new ItemStack(itemOneIn, 1, 0), new ItemStack(itemTwoIn, 1, 0), itemOut);
    }

    public void addRecipeFinal(ItemStack itemOneIn, ItemStack itemTwoIn, ItemStack itemOut) {
        addingKeyList.add(itemOneIn);
        addingKeyList.add(itemTwoIn);
        //addingValueList.add(itemOut);
        
        
        IngotMasherRecipes.mashingList.put(addingKeyList, itemOut);
        
        addingKeyList.clear();
        //addingValueList.clear();

    }

    public static ItemStack getMashingResult(ArrayList<ItemStack> list)           //restructure to take ArrayLists, not ItemStacks
    {
        Iterator iterator = mashingList.entrySet().iterator();
        Map.Entry entry;

        do
        {
            if (!iterator.hasNext())
            {
                return null;
            }

            entry = (Map.Entry)iterator.next();
        }
        while (!func_151397_a(list, (ArrayList<ItemStack>)entry.getKey()));

        return (ItemStack)entry.getValue();
    }

    private static boolean func_151397_a(ArrayList<ItemStack> list, ArrayList<ItemStack> keyBeingChecked)
    {
        return (keyBeingChecked.get(0) == list.get(0) && keyBeingChecked.get(0) == list.get(0)) || (keyBeingChecked.get(1) == list.get(0) && keyBeingChecked.get(0) == list.get(1));
    }

    public Map getMashingList()
    {
        return this.mashingList;
    }

    /* //list-based methods for determining recipe outputs, read off of now-deleted lists.
    public static ItemStack getMashingResult(Item item, Item item2) {
        return getOutput(item, item2);
    }

    public static ItemStack getOutput(Item item, Item item2) {
        for (int i = 0; i < recipeList.length; ++i) {
            int j = 0;
            if (item == recipeList[i][j] && item2 == recipeList[i][j + 1] || item == recipeList[i][j+1] && item2 == recipeList[i][j]) {
                return new ItemStack(recipeList[i][j + 2], amountList[i]);
            } else { 
            return null;
            }
        }
        return null;

    }*/
}

 

 

TileEntity for this machine

package com.exo594.tutorial.tileentities;

import com.exo594.tutorial.IngotMasherRecipes;
import com.exo594.tutorial.block.IngotMasher;
import java.util.ArrayList;
import net.minecraft.entity.player.EntityPlayer;
import net.minecraft.init.Items;
import net.minecraft.inventory.ISidedInventory;
import net.minecraft.item.Item;
import net.minecraft.item.ItemStack;
import net.minecraft.nbt.NBTTagCompound;
import net.minecraft.nbt.NBTTagList;
import net.minecraft.tileentity.TileEntity;

public class TileEntityIngotMasher extends TileEntity implements ISidedInventory {

    ArrayList<ItemStack> mashingResultsList = new ArrayList<ItemStack>();

    public ItemStack slots[];

    public int dualPower;
    public int dualCookTime;
    public static final int maxPower = 10000;
    public static final int mashingSpeed = 100;

    private static final int[] slots_top = new int[]{0, 1};
    private static final int[] slots_bottom = new int[]{3};
    private static final int[] slots_side = new int[]{2};

    private String customName;
    
    public ItemStack result;

    public TileEntityIngotMasher() {
        slots = new ItemStack[4];
    }

    @Override
    public int getSizeInventory() {
        return slots.length;
    }

    @Override
    public ItemStack getStackInSlot(int i) {
        return slots[i];
    }

    @Override
    public ItemStack getStackInSlotOnClosing(int i) {
        if (slots[i] != null) {
            ItemStack itemstack = slots[i];
            slots[i] = null;
            return itemstack;
        } else {
            return null;
        }
    }

    @Override
    public void setInventorySlotContents(int i, ItemStack itemstack) {
        slots[i] = itemstack;
        if (itemstack != null && itemstack.stackSize > getInventoryStackLimit()) {
            itemstack.stackSize = getInventoryStackLimit();
        }
    }

    @Override
    public int[] getAccessibleSlotsFromSide(int i) {
        return i == 0 ? slots_bottom : (i == 1 ? slots_top : slots_side);
    }

    @Override
    public int getInventoryStackLimit() {
        return 64;
    }

    @Override
    public boolean isUseableByPlayer(EntityPlayer player) {
        if (worldObj.getTileEntity(xCoord, yCoord, zCoord) != this) {
            return false;
        } else {
            return player.getDistanceSq((double) xCoord + 0.5D, (double) yCoord + 0.5D, (double) zCoord + 0.5D) <= 64;
        }
    }

    @Override
    public void openInventory() {
    }

    @Override
    public void closeInventory() {
    }

    @Override
    public boolean isItemValidForSlot(int i, ItemStack itemstack) {
        return i == 3 ? false : (i == 2 ? hasItemPower(itemstack) : true);
    }

    public static boolean hasItemPower(ItemStack itemstack) {
        return getItemPower(itemstack) > 0;
    }

    private static int getItemPower(ItemStack itemstack) {
        if (itemstack == null) {
            return 0;
        } else {
            Item item = itemstack.getItem();
            if (item == Items.apple) {
                return 1000;
            } else {
                return 0;
            }
        }
    }

    @Override
    public ItemStack decrStackSize(int i, int j) {
        if (slots[i] != null) {
            if (slots[i].stackSize <= j) {
                ItemStack itemstack = slots[i];
                slots[i] = null;
                return itemstack;
            }

            ItemStack itemstack1 = slots[i].splitStack(j);

            if (slots[i].stackSize == 0) {
                slots[i] = null;
            }

            return itemstack1;
        } else {
            return null;
        }
    }

    @Override
    public void readFromNBT(NBTTagCompound nbt) {
        super.readFromNBT(nbt);
        NBTTagList list = nbt.getTagList("Items", 10);
        slots = new ItemStack[getSizeInventory()];

        for (int i = 0; i < list.tagCount(); i++) {
            NBTTagCompound nbt1 = (NBTTagCompound) list.getCompoundTagAt(i);
            byte b0 = nbt1.getByte("Slot");

            if (b0 >= 0 && b0 < slots.length) {
                slots[b0] = ItemStack.loadItemStackFromNBT(nbt1);
            }
        }

        dualPower = nbt.getShort("PowerTime");
        dualCookTime = nbt.getShort("CookTime");
    }

    @Override
    public void writeToNBT(NBTTagCompound nbt) {
        super.writeToNBT(nbt);
        nbt.setShort("PowerTime", (short) dualPower);
        nbt.setShort("CookTime", (short) dualCookTime);
        NBTTagList list = new NBTTagList();

        for (int i = 0; i < slots.length; i++) {
            if (slots[i] != null) {
                NBTTagCompound nbt1 = new NBTTagCompound();
                nbt1.setByte("Slot", (byte) i);
                slots[i].writeToNBT(nbt1);
                list.appendTag(nbt1);
            }
        }

        nbt.setTag("Items", list);
    }

    @Override
    public String getInventoryName() {
        return "container.ingotMasher";
    }

    @Override
    public boolean canInsertItem(int var1, ItemStack itemstack, int var3) {
        return this.isItemValidForSlot(var1, itemstack);
    }

    @Override
    public boolean canExtractItem(int i, ItemStack itemstack, int j) {
        return j != 0 || i != 1 || itemstack.getItem() == Items.bucket;
    }

    @Override
    public boolean hasCustomInventoryName() {
        return this.customName != null && this.customName.length() > 0;
    }

    public int getMasherProgressScaled(int i) {
        return (dualCookTime * i) / this.mashingSpeed;
    }

    public int getPowerRemainingScaled(int i) {
        return (dualPower * i) / maxPower;
    }

    private boolean canMash() {

        if (slots[0] == null || slots[1] == null) {
            return false;
        }

        if (slots[0] != null && slots[1] != null) {
            
        
        mashingResultsList.add(new ItemStack(this.slots[0].getItem()));
        mashingResultsList.add(new ItemStack(this.slots[1].getItem()));

        result = IngotMasherRecipes.getMashingResult(mashingResultsList);

        mashingResultsList.clear();
        }else{ 
            result = null;
        }
        

        if (result == null) {
            return false;
        }

        if (slots[3] == null) {
            return true;
        }

        if (!slots[3].isItemEqual(result)) {
            return false;
        }

        if (slots[3].stackSize < getInventoryStackLimit() && slots[3].stackSize < slots[3].getMaxStackSize()) {
            return true;
        } else {
            return slots[3].stackSize < result.getMaxStackSize();
        }
    }

    private void mashItem() {
        if (canMash()) {

            if (slots[0] != null && slots[1] != null) {
                mashingResultsList.add(new ItemStack(this.slots[0].getItem()));
                mashingResultsList.add(new ItemStack(this.slots[1].getItem()));

                ItemStack itemstack = IngotMasherRecipes.getMashingResult(mashingResultsList);

                mashingResultsList.clear();

                if (slots[3] == null) {
                    slots[3] = itemstack.copy();
                } else if (slots[3].isItemEqual(itemstack)) {
                    slots[3].stackSize += itemstack.stackSize;
                }

                for (int i = 0; i < 2; i++) {
                    if (slots[i].stackSize <= 0) {
                        slots[i] = new ItemStack(slots[i].getItem().setFull3D());
                    } else {
                        slots[i].stackSize--;
                    }

                    if (slots[i].stackSize <= 0) {
                        slots[i] = null;
                    }
                }
            }
        }
    }

    public boolean hasPower() {
        return dualPower > 0;
    }

    public boolean isMashing() {
        return this.dualCookTime > 0;
    }

    @Override
    public void updateEntity() {
        boolean flag = this.hasPower();
        boolean flag1 = false;

        if (hasPower() && this.isMashing()) {
            this.dualPower--;
        }

        if (!worldObj.isRemote) {
            if (this.hasItemPower(this.slots[2]) && this.dualPower < (this.maxPower - this.getItemPower(this.slots[2]))) {
                this.dualPower += getItemPower(this.slots[2]);

                if (this.slots[2] != null) {
                    flag1 = true;

                    this.slots[2].stackSize--;

                    if (this.slots[2].stackSize == 0) {
                        this.slots[2] = this.slots[2].getItem().getContainerItem(this.slots[2]);
                    }
                }
            }

            if (hasPower() && canMash()) {
                dualCookTime++;

                if (this.dualCookTime == this.mashingSpeed) {
                    this.dualCookTime = 0;
                    this.mashItem();
                    flag1 = true;
                }
            } else {
                dualCookTime = 0;
            }

            if (flag != this.isMashing()) {
                flag1 = true;
                IngotMasher.updateBlockState(this.dualCookTime > 0, this.worldObj, this.xCoord, this.yCoord, this.zCoord);
            }
        }

        if (flag1) {
            this.markDirty();
        }
    }

}

 

Container Class

package com.exo594.tutorial.containers;

import com.exo594.tutorial.IngotMasherRecipes;
import com.exo594.tutorial.slot.SlotIngotMasher;
import com.exo594.tutorial.tileentities.TileEntityIngotMasher;
import cpw.mods.fml.relauncher.Side;
import cpw.mods.fml.relauncher.SideOnly;
import net.minecraft.entity.player.EntityPlayer;
import net.minecraft.entity.player.InventoryPlayer;
import net.minecraft.inventory.Container;
import net.minecraft.inventory.ICrafting;
import net.minecraft.inventory.Slot;
import net.minecraft.item.ItemStack;

public class ContainerIngotMasher extends Container {

    private TileEntityIngotMasher masher;
    private int dualCookTime;
    private int dualPower;
    private int lastItemBurnTime;
    public static final int INPUT_1 = 0, INPUT_2 = 1, FUEL = 2, OUTPUT = 3;

    public ContainerIngotMasher(InventoryPlayer invPlayer, TileEntityIngotMasher teIngotMasher) {
        dualCookTime = 0;
        dualPower = 0;
        lastItemBurnTime = 0;

        masher = teIngotMasher;

        this.addSlotToContainer(new Slot(teIngotMasher, INPUT_1, 45, 17));
        this.addSlotToContainer(new Slot(teIngotMasher, INPUT_2, 45, 49));
        this.addSlotToContainer(new Slot(teIngotMasher, FUEL, 8, 56));
        this.addSlotToContainer(new SlotIngotMasher(invPlayer.player, teIngotMasher, OUTPUT, 113, 33));

        //Inventory
        for (int i = 0; i < 3; i++) {
            for (int j = 0; j < 9; j++) {
                this.addSlotToContainer(new Slot(invPlayer, j + i * 9 + 9, 8 + j * 18, 84 + i * 18));
            }
        }

        //ActionBar
        for (int i = 0; i < 9; i++) {
            this.addSlotToContainer(new Slot(invPlayer, i, 8 + i * 18, 142));
        }
    }

    @Override
    public void addCraftingToCrafters(ICrafting crafting) {
        super.addCraftingToCrafters(crafting);
        crafting.sendProgressBarUpdate(this, 0, this.masher.dualCookTime);
        crafting.sendProgressBarUpdate(this, 1, this.masher.dualPower);
    }

    @Override
    public ItemStack transferStackInSlot(EntityPlayer par1EntityPlayer, int par2) {
        ItemStack itemstack = null;
        Slot slot = (Slot) this.inventorySlots.get(par2);

        if (slot != null && slot.getHasStack()) {
            ItemStack itemstack1 = slot.getStack();
            itemstack = itemstack1.copy();

// If itemstack is in Output stack
            if (par2 == OUTPUT) {
// try to place in player inventory / action bar; add 36+1 because mergeItemStack uses < index,
// so the last slot in the inventory won't get checked if you don't add 1
                if (!this.mergeItemStack(itemstack1, OUTPUT + 1, OUTPUT + 36 + 1, true)) {
                    return null;
                }

                slot.onSlotChange(itemstack1, itemstack);
            } // itemstack is in player inventory, try to place in appropriate furnace slot
            else if (par2 != FUEL && par2 != INPUT_1 && par2 != INPUT_2) {
// if it can be smelted, place in the input slots
                if (IngotMasherRecipes.itemCanBeMashed(itemstack1)) {            //DOES NOT LIKE SOME PART OF THIS LINE
// try to place in either Input slot; add 1 to final input slot because mergeItemStack uses < index
                    if (!this.mergeItemStack(itemstack1, INPUT_1, INPUT_2 + 1, false)) {
                        return null;
                    }
                } // if it's an energy source, place in Fuel slot
                else if (TileEntityIngotMasher.hasItemPower(itemstack1)) {
                    if (!this.mergeItemStack(itemstack1, FUEL, FUEL + 1, false)) {
                        return null;
                    }
                } // item in player's inventory, but not in action bar
                else if (par2 >= OUTPUT + 1 && par2 < OUTPUT + 28) {
// place in action bar
                    if (!this.mergeItemStack(itemstack1, OUTPUT + 28, OUTPUT + 37, false)) {
                        return null;
                    }
                } // item in action bar - place in player inventory
                else if (par2 >= OUTPUT + 28 && par2 < OUTPUT + 37 && !this.mergeItemStack(itemstack1, OUTPUT + 1, OUTPUT + 28, false)) {
                    return null;
                }
            } // In one of the infuser slots; try to place in player inventory / action bar
            else if (!this.mergeItemStack(itemstack1, OUTPUT + 1, OUTPUT + 37, false)) {
                return null;
            }

            if (itemstack1.stackSize == 0) {
                slot.putStack((ItemStack) null);
            } else {
                slot.onSlotChanged();
            }

            if (itemstack1.stackSize == itemstack.stackSize) {
                return null;
            }

            slot.onPickupFromSlot(par1EntityPlayer, itemstack1);
        }
        return itemstack;
    }

    @Override
    public boolean canInteractWith(EntityPlayer player) {
        return masher.isUseableByPlayer(player);
    }

    @Override
    public void detectAndSendChanges() {
        super.detectAndSendChanges();
        for (int i = 0; i < this.crafters.size(); i++) {
            ICrafting icrafting = (ICrafting) this.crafters.get(i);

            if (this.dualCookTime != this.masher.dualCookTime) {
                icrafting.sendProgressBarUpdate(this, 0, this.masher.dualCookTime);
            }
            if (this.dualPower != this.masher.dualPower) {
                icrafting.sendProgressBarUpdate(this, 1, this.masher.dualPower);
            }
        }
        this.dualCookTime = this.masher.dualCookTime;
        this.dualPower = this.masher.dualPower;
    }

    @SideOnly(Side.CLIENT)
    @Override
    public void updateProgressBar(int slot, int newValue) {
        if (slot == 0) {
            this.masher.dualCookTime = newValue;
        }

        if (slot == 1) {
            this.masher.dualPower = newValue;
        }
    }
}

 

Block Class

package com.exo594.tutorial.block;

import com.exo594.tutorial.Main;
import com.exo594.tutorial.tileentities.TileEntityIngotMasher;
import cpw.mods.fml.common.network.internal.FMLNetworkHandler;
import cpw.mods.fml.relauncher.Side;
import cpw.mods.fml.relauncher.SideOnly;
import java.util.Random;
import net.minecraft.block.Block;
import net.minecraft.block.BlockContainer;
import net.minecraft.block.material.Material;
import net.minecraft.client.renderer.texture.IIconRegister;
import net.minecraft.entity.EntityLivingBase;
import net.minecraft.entity.item.EntityItem;
import net.minecraft.entity.player.EntityPlayer;
import net.minecraft.item.ItemStack;
import net.minecraft.nbt.NBTTagCompound;
import net.minecraft.tileentity.TileEntity;
import net.minecraft.util.IIcon;
import net.minecraft.util.MathHelper;
import net.minecraft.world.World;

public class IngotMasher extends BlockContainer {

    private Random rand;
    private final boolean isActive;
    private static boolean keepInventory = true;

    @SideOnly(Side.CLIENT)
    private IIcon iconFront;

    public IngotMasher(String unlocalizedName, boolean blockState) {
        super(Material.iron);
        rand = new Random();
        isActive = blockState;
        this.setBlockName(unlocalizedName);

    }

    @SideOnly(Side.CLIENT)
    @Override
    public void registerBlockIcons(IIconRegister iconRegister) {
        this.blockIcon = iconRegister.registerIcon(Main.MODID + ":" + ("tutoriumFurnaceOther"));
        this.iconFront = iconRegister.registerIcon(Main.MODID + ":" + (this.isActive ? "IngotMasherFrontOn" : "IngotMasherFrontOff"));
    }

    @SideOnly(Side.CLIENT)
    @Override
    public IIcon getIcon(int side, int metadata) {
        return metadata == 0 && side == 3 ? this.iconFront : (side == metadata ? this.iconFront : this.blockIcon);
    }

    @Override
    public void onBlockAdded(World world, int x, int y, int z) {
        super.onBlockAdded(world, x, y, z);
        this.setDefaultDirection(world, x, y, z);
    }

    private void setDefaultDirection(World world, int x, int y, int z) {
        if (!world.isRemote) {
            Block block1 = world.getBlock(x, y, z - 1);
            Block block2 = world.getBlock(x, y, z + 1);
            Block block3 = world.getBlock(x - 1, y, z);
            Block block4 = world.getBlock(x + 1, y, z);

            byte b0 = 3;

            if (block1.func_149730_j() && !block2.func_149730_j()) {
                b0 = 3;
            }

            if (block2.func_149730_j() && !block1.func_149730_j()) {
                b0 = 2;
            }

            if (block3.func_149730_j() && !block4.func_149730_j()) {
                b0 = 5;
            }

            if (block4.func_149730_j() && !block3.func_149730_j()) {
                b0 = 4;
            }

            world.setBlockMetadataWithNotify(x, y, x, b0, 2);
        }
    }

    @Override
    public void onBlockPlacedBy(World world, int x, int y, int z, EntityLivingBase entityPlayer, ItemStack itemstack) {
        int i = MathHelper.floor_double((double) (entityPlayer.rotationYaw * 4.0F / 360F) + 0.5D) & 3;

        if (i == 0) {
            world.setBlockMetadataWithNotify(x, y, z, 2, 2);
        }

        if (i == 1) {
            world.setBlockMetadataWithNotify(x, y, z, 5, 2);
        }

        if (i == 2) {
            world.setBlockMetadataWithNotify(x, y, z, 3, 2);
        }

        if (i == 3) {
            world.setBlockMetadataWithNotify(x, y, z, 4, 2);
        }

        if (itemstack.hasDisplayName()) {
            //((TileEntityIngotMasher)world.getTileEntity(x, y, z)).setCustomName(itemstack.getDisplayName());
        }
    }

    @Override
    public boolean onBlockActivated(World world, int x, int y, int z, EntityPlayer player, int side, float hitX, float hitY, float hitZ) {
        if (world.isRemote) {
            return true;
        } else if (!player.isSneaking()) {
            TileEntityIngotMasher entity = (TileEntityIngotMasher) world.getTileEntity(x, y, z);
            if (entity != null) {
                FMLNetworkHandler.openGui(player, Main.modInstance, Main.guiIDIngotMasher, world, x, y, z);
            }
            return true;
        } else {
            return false;
        }
    }

    @Override
    public TileEntity createNewTileEntity(World var1, int var2) {
        return new TileEntityIngotMasher();
    }

    public static void updateBlockState(boolean isMashing, World world, int xCoord, int yCoord, int zCoord) {

        int i = world.getBlockMetadata(xCoord, yCoord, zCoord);
        TileEntity entity = world.getTileEntity(xCoord, yCoord, zCoord);
        keepInventory = true;

        if (isMashing) {
            world.setBlock(xCoord, yCoord, zCoord, ModBlocks.blockIngotMasherActive);
        } else {
            world.setBlock(xCoord, yCoord, zCoord, ModBlocks.blockIngotMasherIdle);
        }

        keepInventory = false;
        world.setBlockMetadataWithNotify(xCoord, yCoord, zCoord, i, 2);

        if (entity != null) {
            entity.validate();
            world.setTileEntity(xCoord, yCoord, zCoord, entity);
        }
    }

    @Override
    public void breakBlock(World world, int x, int y, int z, Block oldblock, int oldMetadata) {
        if (!keepInventory) {
            TileEntityIngotMasher tileentity = (TileEntityIngotMasher) world.getTileEntity(x, y, z);

            if (tileentity != null) {
                for (int i = 0; i < tileentity.getSizeInventory(); i++) {
                    ItemStack itemstack = tileentity.getStackInSlot(i);

                    if (itemstack != null) {
                        float f = this.rand.nextFloat() * 0.8F + 0.1F;
                        float f1 = this.rand.nextFloat() * 0.8F + 0.1F;
                        float f2 = this.rand.nextFloat() * 0.8F + 0.1F;

                        while (itemstack.stackSize > 0) {
                            int j = this.rand.nextInt(21) + 10;

                            if (j > itemstack.stackSize) {
                                j = itemstack.stackSize;
                            }

                            itemstack.stackSize -= j;

                            EntityItem item = new EntityItem(world, (double) ((float) x + f), (double) ((float) y + f1), (double) ((float) z + f2), new ItemStack(itemstack.getItem(), j, itemstack.getItemDamage()));

                            if (itemstack.hasTagCompound()) {
                                item.getEntityItem().setTagCompound((NBTTagCompound) itemstack.getTagCompound().copy());
                            }

                            world.spawnEntityInWorld(item);
                        }
                    }
                }

                world.func_147453_f(x, y, z, oldblock);
            }
        }

        super.breakBlock(world, x, y, z, oldblock, oldMetadata);
    }
}

 

HerpaDerp, crashlog.

 

 

---- Minecraft Crash Report ----

// Don't do that.

 

Time: 9/4/15 7:53 PM

Description: Ticking block entity

 

java.lang.ExceptionInInitializerError

at com.exo594.tutorial.tileentities.TileEntityIngotMasher.canMash(TileEntityIngotMasher.java:215)

at com.exo594.tutorial.tileentities.TileEntityIngotMasher.updateEntity(TileEntityIngotMasher.java:306)

at net.minecraft.world.World.updateEntities(World.java:2160)

at net.minecraft.world.WorldServer.updateEntities(WorldServer.java:515)

at net.minecraft.server.MinecraftServer.updateTimeLightAndEntities(MinecraftServer.java:703)

at net.minecraft.server.MinecraftServer.tick(MinecraftServer.java:614)

at net.minecraft.server.integrated.IntegratedServer.tick(IntegratedServer.java:118)

at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:485)

at net.minecraft.server.MinecraftServer$2.run(MinecraftServer.java:752)

Caused by: java.lang.NullPointerException

at com.exo594.tutorial.IngotMasherRecipes.<init>(IngotMasherRecipes.java:33)

at com.exo594.tutorial.IngotMasherRecipes.<clinit>(IngotMasherRecipes.java:18)

... 9 more

 

 

A detailed walkthrough of the error, its code path and all known details is as follows:

---------------------------------------------------------------------------------------

 

-- Head --

Stacktrace:

at com.exo594.tutorial.tileentities.TileEntityIngotMasher.canMash(TileEntityIngotMasher.java:215)

at com.exo594.tutorial.tileentities.TileEntityIngotMasher.updateEntity(TileEntityIngotMasher.java:306)

 

-- Block entity being ticked --

Details:

Name: IngotMasher // com.exo594.tutorial.tileentities.TileEntityIngotMasher

Block type: ID #176 (tile.IngotMasherIdle // com.exo594.tutorial.block.IngotMasher)

Block data value: 4 / 0x4 / 0b0100

Block location: World: (201,64,242), Chunk: (at 9,4,2 in 12,15; contains blocks 192,0,240 to 207,255,255), Region: (0,0; contains chunks 0,0 to 31,31, blocks 0,0,0 to 511,255,511)

Actual block type: ID #176 (tile.IngotMasherIdle // com.exo594.tutorial.block.IngotMasher)

Actual block data value: 4 / 0x4 / 0b0100

Stacktrace:

at net.minecraft.world.World.updateEntities(World.java:2160)

at net.minecraft.world.WorldServer.updateEntities(WorldServer.java:515)

 

-- Affected level --

Details:

Level name: New World

All players: 1 total; [EntityPlayerMP['Player15'/464, l='New World', x=200.50, y=64.00, z=242.50]]

Chunk stats: ServerChunkCache: 683 Drop: 0

Level seed: 9088348090430973558

Level generator: ID 00 - default, ver 1. Features enabled: true

Level generator options:

Level spawn location: World: (196,64,235), Chunk: (at 4,4,11 in 12,14; contains blocks 192,0,224 to 207,255,239), Region: (0,0; contains chunks 0,0 to 31,31, blocks 0,0,0 to 511,255,511)

Level time: 2061 game time, 2061 day time

Level dimension: 0

Level storage version: 0x04ABD - Anvil

Level weather: Rain time: 36157 (now: false), thunder time: 38794 (now: false)

Level game mode: Game mode: creative (ID 1). Hardcore: false. Cheats: true

Stacktrace:

at net.minecraft.server.MinecraftServer.updateTimeLightAndEntities(MinecraftServer.java:703)

at net.minecraft.server.MinecraftServer.tick(MinecraftServer.java:614)

at net.minecraft.server.integrated.IntegratedServer.tick(IntegratedServer.java:118)

at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:485)

at net.minecraft.server.MinecraftServer$2.run(MinecraftServer.java:752)

 

-- System Details --

Details:

Minecraft Version: 1.7.10

Operating System: Windows 8.1 (amd64) version 6.3

Java Version: 1.7.0_79, Oracle Corporation

Java VM Version: Java HotSpot 64-Bit Server VM (mixed mode), Oracle Corporation

Memory: 311678400 bytes (297 MB) / 616562688 bytes (588 MB) up to 1782054912 bytes (1699 MB)

JVM Flags: 0 total;

AABB Pool Size: 0 (0 bytes; 0 MB) allocated, 0 (0 bytes; 0 MB) used

IntCache: cache: 0, tcache: 0, allocated: 12, tallocated: 94

FML: MCP v9.05 FML v7.10.99.99 Minecraft Forge 10.13.4.1448 4 mods loaded, 4 mods active

States: 'U' = Unloaded 'L' = Loaded 'C' = Constructed 'H' = Pre-initialized 'I' = Initialized 'J' = Post-initialized 'A' = Available 'D' = Disabled 'E' = Errored

UCHIJAAAA mcp{9.05} [Minecraft Coder Pack] (minecraft.jar)

UCHIJAAAA FML{7.10.99.99} [Forge Mod Loader] (forgeSrc-1.7.10-10.13.4.1448-1.7.10.jar)

UCHIJAAAA Forge{10.13.4.1448} [Minecraft Forge] (forgeSrc-1.7.10-10.13.4.1448-1.7.10.jar)

UCHIJAAAA tutorial{1.0.0} [Tutorial Mod] (modid-1.0.jar)

GL info: ~~ERROR~~ RuntimeException: No OpenGL context found in the current thread.

Profiler Position: N/A (disabled)

Vec3 Pool Size: 0 (0 bytes; 0 MB) allocated, 0 (0 bytes; 0 MB) used

Player Count: 1 / 8; [EntityPlayerMP['Player15'/464, l='New World', x=200.50, y=64.00, z=242.50]]

Type: Integrated Server (map_client.txt)

Is Modded: Definitely; Client brand changed to 'fml,forge'

 

 

I'm not sure about the crash, but:

 

keyBeingChecked.get(0) == list.get(0)

 

That will never return true.  ItemStacks don't override the == opperator, and even .equals() is kind of iffy.

You are getting a null pointer on line 33:

Caused by: java.lang.NullPointerException
   at com.exo594.tutorial.IngotMasherRecipes.<init>(IngotMasherRecipes.java:33)

What's on line 33?

 

Re: Draco's reply - you can, however, use the various equality-related methods within the ItemStack class, or simply compare the #getItem() and #getItemDamage() of the two stacks.

Line 33 of IngotMasherRecipes is this:

 

addMashingRecipeWithTwoItems(ModItems.tutorialItem, Items.bread, new ItemStack(ModItems.tutoriumLoaf));

 

Which is part of this:

 

private IngotMasherRecipes() {
        addMashingRecipeWithTwoItems(ModItems.tutorialItem, Items.bread, new ItemStack(ModItems.tutoriumLoaf));
        addMashingRecipeWithTwoItems(Items.iron_ingot, ModItems.tutorialItem, new ItemStack(ModItems.craftingPendulum));
        addMashingRecipeWithOneBlock(Blocks.glowstone, Items.diamond, new ItemStack(ModItems.tutoriumGrenade, 1));
    }

Oh, that's because you're trying to register your recipes when the class loads and before Vanilla has defined its items.  Items.bread is null (and so are your mod items).

This might be totally obvious, but how do I get around that issue?

 

If I put these:

 

addMashingRecipeWithTwoItems(ModItems.tutorialItem, Items.bread, new ItemStack(ModItems.tutoriumLoaf));

addMashingRecipeWithTwoItems(Items.iron_ingot, ModItems.tutorialItem, new ItemStack(ModItems.craftingPendulum));

addMashingRecipeWithOneBlock(Blocks.glowstone, Items.diamond, new ItemStack(ModItems.tutoriumGrenade, 1));

 

inside another method, and then call that method in the same place that I call my shaped, shapeless, and smelting recipes from, would that take care of the issue?

Yes, you should make a public method for your masher recipes and add recipes at the same time you do all your others, e.g. at the end of pre-initialization after everything else has been initialized.

After changing out the recipe locations, shifting around the way my ArrayLists were called to ensure the HashMap was constructed properly, and implementing the .getItem() bits, I am pleased to say that everything works properly now. Thank you both for your help.