[1.6.4]Crashing but only on server with getIcon (arrayindexoutofbounds)

[skullywag]

Hey all,

 

Not sure what wrong here but im getting a crash when trying to join the server I start from eclipse with my mod loaded. The crash:

 

java.lang.ArrayIndexOutOfBoundsException: 15
at spawnCrystals.BlockCustomSpawner.getIcon(BlockCustomSpawner.java:47)

 

now that method is literally 1 line, ill add the relevant parts from my block class below:

 

private Icon[] icons;

    public void registerIcons(IconRegister par1IconRegister)
{
	icons = new Icon[13];

	for(int i = 0; i < icons.length; i++)
	{
		icons[i] = par1IconRegister.registerIcon(spawnCrystals.modid + ":" + (this.getUnlocalizedName().substring(5)) + i);
	}
}

public Icon getIcon(int par1, int par2)
{
	return icons[par2];
}

 

anyone have any idea why this crashes on the getIcon method? Ive also made sure there are 13 metadata blocks in this block ID all numbered correctly when registered in my main class.

 

edit - hmm par2 does seem to be 15 for some reason on loading into the world....how strange...but only on a server???

[Draco18s]

Metadata ranges from 0 to 15.

 

Your icon array ranges from 0 to 13.

 

Take a WILD guess.

[skullywag]

Ok I will, im guessing by your statement you think the icons = new Icon[13]; should be  icons = new Icon[15]; youd be wrong. Ive learned that this icon array needs to be the same number as you have of metadata block. Changing it to 15 causes the reverse error: arrayindexoutofbounds 13. Doing this also crashes the client mode. As stated this ONLY crashed on the server its fine on just the client as is.

[skullywag]

ok after some more debugging and backtracing ive discovered that one of my blocks is actually in the world (I have no idea why, i didnt put it there), doing this:

 

public Icon getBlockTexture(IBlockAccess par1IBlockAccess, int par2, int par3, int par4, int par5)
    {
    	System.out.println("META -" + par1IBlockAccess.getBlockMetadata(par2, par3, par4));
    	System.out.println("pos - " + par2 + "," + par3 + "," + par4);
        return this.getIcon(par5, par1IBlockAccess.getBlockMetadata(par2, par3, par4));
    }

 

results in

 

2014-01-21 01:27:46 [iNFO] [sTDOUT] META -15

2014-01-21 01:27:46 [iNFO] [sTDOUT] pos - -194,69,240

 

(I also printed out the blockID in another test and it is my custom blockID) which I take to mean one of my custom blocks has entered the world somehow, now as they are mob spawners im guessing theres a mob spawner at those coords, however my block/TE doesnt even mention blockMobSpawner or its tileentity and it shouldnt be referencing mine so how on earth did it get there, this is gonna end up being such a silly error by me I know it.

[Draco18s]

2014-01-21 01:27:46 [iNFO] [sTDOUT] META -15

2014-01-21 01:27:46 [iNFO] [sTDOUT] pos - -194,69,240

 

Bingo.

 

What you should do in your getIcon method is check for out of bounds and return a default icon (icons[0] is a good choice, so is null) just in case something like this happens.

[DiabolusNeil]

"Goes to Minecraft Forge Forums for help with crashing mod, doesn't read crash report, problem was a common Java error that can be fixed in 5 seconds."

[skullywag]

It states I read the crash report in the OP if youd open your eyes. It also states it worked fine in CLIENT ONLY MODE, I wanted to know why when running on a server I was getting the wrong meta data returned for a block I hadnt even placed. Literally on server login Id crash with that error.

 

Turns out it was actually the world that was the issue and I had some left over ghost block or something (still dont know really). Killing the world and restarting got rid of part of the problem. So it might of seemed like a "common Java error" but it wasnt,  So before you open your mouth and add nothing comments to my threads use your brain.

[Draco18s]

And if you put sanity checks in your getIcon function, you wouldn't have had the problem anyway.

[skullywag]

and from now on I will, please bare in mind that none of the forge tutorials and none of the tutorials submitted by third parties (like wuppy for instance) show doing this in this particular method (unless im blind), I understand its good practice in all programming languages and from now on ill remember to do it wherever I can to avoid such issues, this is all a learning experience for me and when it works perfectly fine in the Client you can surely understand my confusion. I understood the error fully I just couldnt understand HOW it was happening. Youve helped me a few times Draco18s and for that im grateful, however the guy trying to belittle me on a public forum for no reason whatsoever is just petty and uncalled for and I will always defend myself against such "trolls" especially when looking at their post history they get stuck on the same simple things I was getting stuck on.

 

Anyways this lesson is learned, onto the next thing to learn.

[Draco18s]

and from now on I will, please bare in mind that none of the forge tutorials and none of the tutorials submitted by third parties (like wuppy for instance) show doing this in this particular method (unless im blind)

 

I do.

 

https://github.com/Draco18s/Artifacts/blob/master/draco18s/artifacts/item/ItemArtifact.java

 

(See how I check for null, and if null, I return a default non-null icon)

 

I feel like I've got an array-based something somewhere, but I can't recall which mod that was offhand, much less which block or item.