Solved Getting Item Durability

I am attempting to make an item return an amount of ingots depending on it's durability. This method seems to work but only if the durability is 100%.

At 100%, I will get 5 ingots from smelting a helmet. If the item is damaged at all I get 2 ingots. I do have a config file which initially sets the amount of ingots to 2 but I'm not sure why that would conflict with the code. The logic seems fine to me but maybe someone else can spot the issue.

conifg example ...

Code:

IronHelmet:
    ingots: 2

Code ...

Code:

  @EventHandler
  public void onFurnaceSmeltEvent(FurnaceSmeltEvent e) {
      ItemStack item = e.getSource();
      int max = item.getType().getMaxDurability();
      int uses = e.getSource().getDurability();
      int percent = 100 - (uses / max * 100);
   
      ItemStack IronHelmet = new ItemStack(Material.IRON_HELMET);
   
      if (item.equals(IronHelmet)){
          int amount = 5;
       
          if (percent >= 75)
              e.setResult(new ItemStack(Material.IRON_INGOT, amount));
          else if (percent >= 50){
              amount = 4;
              e.setResult(new ItemStack(Material.IRON_INGOT, amount));
          }
          else if (percent >= 25){
              amount = 3;
              e.setResult(new ItemStack(Material.IRON_INGOT, amount));
          }
          else if (percent > 0){
              amount = 2;
              e.setResult(new ItemStack(Material.IRON_INGOT, amount));
          }
      }
  }

Eventually I will be using this for multiple items and I'd rather not copy and paste this for each item. I tried to write an algorithm to detect what material should be returned in the result but that just failed.

 

Try (new Double(uses) / new Double(max))

Or (100.0 * uses / max)

 

Wouldn't that give me the the percent durability used rather than what is left?

ex. uses = 25; max = 166;

100 * 25/166 = 15

[Edit] Oh wait... durability is subtracted from the total isn't it.... so uses would be 141. Is that right?

 

Sry if I wasn’t clear enough.
Not sure why you are getting 2, but there are two problems.

1) item.equals(IronHelmet) change to item.getType() == IRON_HELMET;
Otherwise equals() would return always return false if damaged, because item with 7 durability does not equal the same item with 34 durability
same thing with enchantments

2) change int percent = 100 - (uses / max * 100); to int percent = 100 - (100.0 * uses / max);
uses / max would always be zero, because it is rounded to a int
I would suggest you use double percent and ignore the *100

 

Right. That makes a lot of sense. If item.equals(Material.IRON_HELMET) it would be looking for a helmet at full durability. uses / max would be a decimal which, because it's an int type, truncates the decimal to an integer of 0.

(I'm just re stating what you said to make sure I understand it correctly)

That should fix it up. Thanks for the help!

 

Just in case: you meant item.equals(IronHelmet) not item.equals(Material.IRON_HELMET).
But yeah, that is what I meant.

In other words: equals() checks everything (ench, dur etc), not just item type.

I don’t know if it is just me, but I always use 1.0 as 100%. It makes sense, because you want it to be a double anyway. And it is easier to do operations: newAmount = amount * percent, instead of newAmount = amount * percent / 100. Just a tip.

Also, when you get your code working, add [SOLVED] to your title. Tag me if you need a reply.

 

andf54 Okay so my code is cleaned up a bit now thanks to your suggestions but now I'm receiving a null pointer exception. Here is what I've got:

Code:

  @EventHandler
  public void onFurnaceSmeltEvent(FurnaceSmeltEvent e) {
      ItemStack item = e.getSource();
      double max = item.getType().getMaxDurability();
      double uses = e.getSource().getDurability();
      double percent = uses/max;
 
      if (item.getType() == Material.IRON_HELMET){
      int amount = getConfig().getInt("IronHelmet.ingots");
      int newAmount = (int) (amount * percent);
 
      e.setResult(new ItemStack(Material.IRON_INGOT, newAmount));
      }
  }

 

Where it points to?

I'm guessing getConfig().getInt("IronHelmet.ingots"); is null;

Also, make sure the amount return is correct or you will have an exploit. Pickaxe = 3 iron, shovel = 1 iron etc.

I dont think the amount of iron required for forging items will change so it is ok to hard code the amounts.

Or you can do something like if(getConfig().getInt("IronHelmet.ingots") == null{amount = getAmount(item)} else { amount = getConfig().getInt("IronHelmet.ingots")}

 

andf54
Here is the stack trace:

Code:

14:05:55 [WARNING] Failed to handle packet: java.lang.NullPointerException
java.lang.NullPointerException
        at net.minecraft.server.SlotFurnaceResult.c(SourceFile:49)
        at net.minecraft.server.SlotFurnaceResult.b(SourceFile:37)
        at net.minecraft.server.Container.clickItem(Container.java:201)
        at net.minecraft.server.NetServerHandler.a(NetServerHandler.java:1115)
        at net.minecraft.server.Packet102WindowClick.handle(SourceFile:29)
        at net.minecraft.server.NetworkManager.b(NetworkManager.java:276)
        at net.minecraft.server.NetServerHandler.d(NetServerHandler.java:109)
        at net.minecraft.server.ServerConnection.b(SourceFile:35)
        at net.minecraft.server.DedicatedServerConnection.b(SourceFile:30)
        at net.minecraft.server.MinecraftServer.q(MinecraftServer.java:578)
        at net.minecraft.server.DedicatedServer.q(DedicatedServer.java:213)
        at net.minecraft.server.MinecraftServer.p(MinecraftServer.java:474)
        at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:406)
        at net.minecraft.server.ThreadServerApplication.run(SourceFile:539)
>

There isn't a line number for me to check and I see it has to do with the result. I tried to hardcode the amounts in.

Code:

  @EventHandler
  public void onFurnaceSmeltEvent(FurnaceSmeltEvent e) {
      ItemStack item = e.getSource();
      double max = item.getType().getMaxDurability();
      double uses = item.getDurability();
      double percent = uses/max;
     
      if (item.getType() == Material.IRON_HELMET){
          int amount = 5;
          int newAmount = (int) (amount * percent);
         
          e.setResult(new ItemStack(Material.IRON_INGOT, newAmount));
      }
  }

From what I can see, I believe that the variable "percent" is somehow always amounting to 0. I tried this:

int newAmount = (int) (amount * percent) + 1;

This gave me back 1 ingot.

The only option I can think of is that the arithmetic is wrong. Correct me if I'm wrong. An iron helmet has a durability of 166. Assuming the item is at full durability item.getType().getMaxDurability will return 166, item.getDurability() will return 166. "percent" (uses/max) 166/166 = 1, yet I get a null pointer exception.

Okay I got it. item.getDurability() returns 0 if the item is at full durability it works perfectly fine now.

EDIT by Moderator: merged posts, please use the edit button instead of double posting.