Fuel Handler
package mrkirby153.MscHouses.core.handlers;

import java.util.ArrayList;
import java.util.logging.Level;

import mrkirby153.MscHouses.core.helpers.LogHelper;
import net.minecraft.item.Item;

public class FuelHandler {

    public static ArrayList<Item> validFuels = new ArrayList<Item>();

    public static void addFuel(Item fuel){
        FuelHandler.validFuels.add(fuel);
        LogHelper.log(Level.ALL, "Successfully registered fuel: " + fuel);
    }

    public static ArrayList<Item> getValidFuelsAsArrayList(){
        return validFuels;
    }

    public static Item[] getValidFulesAsList(){
        Item[] fuels = new Item[validFuels.size()];
        fuels = validFuels.toArray(fuels);
        return fuels;
    }
}
---------------------------------
Fuel Helper

package mrkirby153.MscHouses.core.helpers;

import java.util.ArrayList;
import java.util.logging.Level;

import mrkirby153.MscHouses.core.handlers.FuelHandler;
import net.minecraft.item.Item;

public class FuelHelper {

    public static void registerFuels(){
        //Adds fuels
        //Default fuels
        FuelHandler.addFuel(Item.coal);
        FuelHandler.addFuel(Item.bucketLava);
        FuelHandler.addFuel(Item.netherStar);
        //Gets and prints the arraylist as an ArrayList
        ArrayList<Item> fuels_arrayList = FuelHandler.getValidFuelsAsArrayList();
        LogHelper.log(Level.SEVERE, fuels_arrayList.toString());
        //gets and prints the arraylist as a Array;
        Item[] fuels_List = FuelHandler.getValidFulesAsList();
        for(int i = 1; i < fuels_List.length; i++){
            LogHelper.log(Level.SEVERE, fuels_List[i].toString());
        }
    }

}

----------------------
Error Log

2013-06-13 15:19:16 [INFO] [STDERR] java.lang.NullPointerException
2013-06-13 15:19:16 [INFO] [STDERR]     at mrkirby153.MscHouses.core.handlers.FuelHandler.addFuel(FuelHandler.java:14)
2013-06-13 15:19:16 [INFO] [STDERR]     at mrkirby153.MscHouses.core.helpers.FuelHelper.registerFuels(FuelHelper.java:15)
2013-06-13 15:19:16 [INFO] [STDERR]     at mrkirby153.MscHouses.core.MscHouses.preInit(MscHouses.java:78)
2013-06-13 15:19:16 [INFO] [STDERR]     at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
2013-06-13 15:19:16 [INFO] [STDERR]     at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
2013-06-13 15:19:16 [INFO] [STDERR]     at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
2013-06-13 15:19:16 [INFO] [STDERR]     at java.lang.reflect.Method.invoke(Unknown Source)
2013-06-13 15:19:16 [INFO] [STDERR]     at cpw.mods.fml.common.FMLModContainer.handleModStateEvent(FMLModContainer.java:494)
2013-06-13 15:19:16 [INFO] [STDERR]     at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
2013-06-13 15:19:16 [INFO] [STDERR]     at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
2013-06-13 15:19:16 [INFO] [STDERR]     at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
2013-06-13 15:19:16 [INFO] [STDERR]     at java.lang.reflect.Method.invoke(Unknown Source)
2013-06-13 15:19:16 [INFO] [STDERR]     at com.google.common.eventbus.EventHandler.handleEvent(EventHandler.java:74)
2013-06-13 15:19:16 [INFO] [STDERR]     at com.google.common.eventbus.SynchronizedEventHandler.handleEvent(SynchronizedEventHandler.java:45)
2013-06-13 15:19:16 [INFO] [STDERR]     at com.google.common.eventbus.EventBus.dispatch(EventBus.java:314)
2013-06-13 15:19:16 [INFO] [STDERR]     at com.google.common.eventbus.EventBus.dispatchQueuedEvents(EventBus.java:296)
2013-06-13 15:19:16 [INFO] [STDERR]     at com.google.common.eventbus.EventBus.post(EventBus.java:267)
2013-06-13 15:19:16 [INFO] [STDERR]     at cpw.mods.fml.common.LoadController.propogateStateMessage(LoadController.java:165)
2013-06-13 15:19:16 [INFO] [STDERR]     at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
2013-06-13 15:19:16 [INFO] [STDERR]     at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
2013-06-13 15:19:16 [INFO] [STDERR]     at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
2013-06-13 15:19:16 [INFO] [STDERR]     at java.lang.reflect.Method.invoke(Unknown Source)
2013-06-13 15:19:16 [INFO] [STDERR]     at com.google.common.eventbus.EventHandler.handleEvent(EventHandler.java:74)
2013-06-13 15:19:16 [INFO] [STDERR]     at com.google.common.eventbus.SynchronizedEventHandler.handleEvent(SynchronizedEventHandler.java:45)
2013-06-13 15:19:16 [INFO] [STDERR]     at com.google.common.eventbus.EventBus.dispatch(EventBus.java:314)
2013-06-13 15:19:16 [INFO] [STDERR]     at com.google.common.eventbus.EventBus.dispatchQueuedEvents(EventBus.java:296)
2013-06-13 15:19:16 [INFO] [STDERR]     at com.google.common.eventbus.EventBus.post(EventBus.java:267)
2013-06-13 15:19:16 [INFO] [STDERR]     at cpw.mods.fml.common.LoadController.distributeStateMessage(LoadController.java:98)
2013-06-13 15:19:16 [INFO] [STDERR]     at cpw.mods.fml.common.Loader.loadMods(Loader.java:514)
2013-06-13 15:19:16 [INFO] [STDERR]     at cpw.mods.fml.client.FMLClientHandler.beginMinecraftLoading(FMLClientHandler.java:160)
2013-06-13 15:19:16 [INFO] [STDERR]     at net.minecraft.client.Minecraft.startGame(Minecraft.java:411)
2013-06-13 15:19:16 [INFO] [STDERR]     at net.minecraft.client.MinecraftAppletImpl.startGame(MinecraftAppletImpl.java:44)
2013-06-13 15:19:16 [INFO] [STDERR]     at net.minecraft.client.Minecraft.run(Minecraft.java:733)
2013-06-13 15:19:16 [INFO] [STDERR]     at java.lang.Thread.run(Unknown Source)