Add items to inventory, gives StackTrace.

Hi! I am in need of help! I have no been active on the forums much lately, this is my first post in ages. Apart from that; it seems that I cannot add the items from a players inventory. Not too sure why. Here is my code:

Code:

            Inventory inventory = Bukkit.createInventory(null, 45,
                                  targetPlayer.getName() + "'s Inventory!");
          
            for(ItemStack item : targetPlayer.getInventory().getContents()){
                //if(item == null) continue; // Makes me unable to use AIR as a material. Unfortunatly.
                inventory.addItem(item);
            }

Like the annotation states. Using that; I am unable to use AIR. As I get an error:

Code:

[16:34:22 INFO]: CraftCreeper6 issued server command: /is CraftCreeper6
[16:34:22 ERROR]: null
org.bukkit.command.CommandException: Unhandled exception executing command 'is'
in plugin InvSeePlus v1.0
        at org.bukkit.command.PluginCommand.execute(PluginCommand.java:46) ~[Cra
ftbukkit.jar:git-Bukkit-1.7.9-R0.2-10-ge6cd8c0-b3096jnks]
        at org.bukkit.command.SimpleCommandMap.dispatch(SimpleCommandMap.java:18
0) ~[Craftbukkit.jar:git-Bukkit-1.7.9-R0.2-10-ge6cd8c0-b3096jnks]
        at org.bukkit.craftbukkit.v1_7_R3.CraftServer.dispatchCommand(CraftServe
r.java:742) ~[Craftbukkit.jar:git-Bukkit-1.7.9-R0.2-10-ge6cd8c0-b3096jnks]
        at net.minecraft.server.v1_7_R3.PlayerConnection.handleCommand(PlayerCon
nection.java:956) [Craftbukkit.jar:git-Bukkit-1.7.9-R0.2-10-ge6cd8c0-b3096jnks]
        at net.minecraft.server.v1_7_R3.PlayerConnection.a(PlayerConnection.java
:817) [Craftbukkit.jar:git-Bukkit-1.7.9-R0.2-10-ge6cd8c0-b3096jnks]
        at net.minecraft.server.v1_7_R3.PacketPlayInChat.a(PacketPlayInChat.java
:28) [Craftbukkit.jar:git-Bukkit-1.7.9-R0.2-10-ge6cd8c0-b3096jnks]
        at net.minecraft.server.v1_7_R3.PacketPlayInChat.handle(PacketPlayInChat
.java:47) [Craftbukkit.jar:git-Bukkit-1.7.9-R0.2-10-ge6cd8c0-b3096jnks]
        at net.minecraft.server.v1_7_R3.NetworkManager.a(NetworkManager.java:157
) [Craftbukkit.jar:git-Bukkit-1.7.9-R0.2-10-ge6cd8c0-b3096jnks]
        at net.minecraft.server.v1_7_R3.ServerConnection.c(SourceFile:134) [Craf
tbukkit.jar:git-Bukkit-1.7.9-R0.2-10-ge6cd8c0-b3096jnks]
        at net.minecraft.server.v1_7_R3.MinecraftServer.v(MinecraftServer.java:6
67) [Craftbukkit.jar:git-Bukkit-1.7.9-R0.2-10-ge6cd8c0-b3096jnks]
        at net.minecraft.server.v1_7_R3.DedicatedServer.v(DedicatedServer.java:2
60) [Craftbukkit.jar:git-Bukkit-1.7.9-R0.2-10-ge6cd8c0-b3096jnks]
        at net.minecraft.server.v1_7_R3.MinecraftServer.u(MinecraftServer.java:5
58) [Craftbukkit.jar:git-Bukkit-1.7.9-R0.2-10-ge6cd8c0-b3096jnks]
        at net.minecraft.server.v1_7_R3.MinecraftServer.run(MinecraftServer.java
:469) [Craftbukkit.jar:git-Bukkit-1.7.9-R0.2-10-ge6cd8c0-b3096jnks]
        at net.minecraft.server.v1_7_R3.ThreadServerApplication.run(SourceFile:6
28) [Craftbukkit.jar:git-Bukkit-1.7.9-R0.2-10-ge6cd8c0-b3096jnks]
Caused by: java.lang.IllegalArgumentException: Item cannot be null
        at org.apache.commons.lang.Validate.noNullElements(Validate.java:410) ~[
Craftbukkit.jar:git-Bukkit-1.7.9-R0.2-10-ge6cd8c0-b3096jnks]
        at org.bukkit.craftbukkit.v1_7_R3.inventory.CraftInventory.addItem(Craft
Inventory.java:268) ~[Craftbukkit.jar:git-Bukkit-1.7.9-R0.2-10-ge6cd8c0-b3096jnk
s]
        at com.live.craftdev.Commands.onCommand(Commands.java:57) ~[?:?]
        at org.bukkit.command.PluginCommand.execute(PluginCommand.java:44) ~[Cra
ftbukkit.jar:git-Bukkit-1.7.9-R0.2-10-ge6cd8c0-b3096jnks]
        ... 13 more

Line 57:

Code:

inventory.addItem(item);

Thank you for reading. Hope someone can help!

 

@CraftCreeper6

It says right there in the stack trace "java.lang.IllegalArgumentException: Item cannot be null," I don't know how it could honestly be any more clear.

 

@mythbusterma
I know this... As you see in my code, I added a check, although, I do not want the item to be nothing, I want it to be air... It says it in the code as an annotation...

 

@CraftCreeper6

If you want to do that, I would recommend making the for loop iterate from 0 to inventory length, and then setting the slot, rather than just add item, that way skipping a slot would allow you to effectively put air in the slot.

 

@mythbusterma @CraftCreeper6 While that works, isn't setting it to air essentially just deleting that spot in the inventory? So wouldn't it be a bit simpler to just clear that inventory slot?

 

@wesley27

If you set a spot to air, adding an item to the inventory will still try to utilise that space that you set to air, because as far as it's concerned, it's empty.

 

I don't like how Bukkit doesn't make it clear whether an item is null or AIR. I wish there was a bit more leeway of dealing with AIR slots. An blank spot could be null or AIR. Because of this, I have to perform such checks like

Code:

itemStack != null && itemStack.getType() != Material.AIR

(I got an error thrown when naming an AIR ItemStack, It wasn't null, it was AIR)
That code bit might be what stops the OPs error from happening.

 

@CraftCreeper6 Well as @mythbusterma said, use the set Method. The best thing would simply be, if you check it it's null or AIR, and set the Item to AIR instead of continuing.

With this you have the same empty/blank spots like the origin Inventory and you dont have any troubles.