Title says it all. How would I go about saving ArrayList<TileEntity> to NBT in my tile entity class?

Wow, I didnt think it would be that easy. Thanks.

Am I on the right track here?

 

@Override
public void writeToNBT(NBTTagCompound nbt){
    	super.writeToNBT(nbt);  
    	nbt.setByte("renderValue", this.renderValue);
    	nbt.setString("state", this.state);
    	
    	NBTTagCompound siren = new NBTTagCompound();

    	for (int i = 0; i < sirens.size(); i++){
        	siren.setInteger("x" + i, sirens.get(i).xCoord);
        	siren.setInteger("y" + i, sirens.get(i).yCoord);
        	siren.setInteger("z" + i, sirens.get(i).zCoord);
        	siren.setInteger("listSize", i);
    	}
    	

    	NBTTagList list = new NBTTagList();
    	
    	list.appendTag(siren);
    	
    	nbt.setTag("sirens", list);
}

@Override
public void readFromNBT(NBTTagCompound nbt){
	super.readFromNBT(nbt);
	this.renderValue = nbt.getByte("renderValue");
	this.state = nbt.getString("state");

	NBTTagList list = (NBTTagList) nbt.getTag("sirens"); 
	NBTTagCompound siren = list.getCompoundTagAt(0);

	for (int i = 0; i < siren.getInteger("listSize"); i ++){
		TileEntity tile = new TileEntity();
		//tile.xCoord is (siren.getInteger("x" + i);
		this.sirens.add(tile);
	}

}

Yes and No, you redesigned wheel.

 

Example:

NBTTagCompound mainNBT = new NBTTagCompound(); //pareent nbt
NBTTagList history = new NBTTagList(); // the list
NBTTagCompound level; //tag in list on "i" index
for (int lvl = 0; lvl <= this.getLevel(); ++lvl)
{
level = new NBTTagCompound(); // each "i" index has one NBT

level.setString("A", a); // write whatever you want in given NBT index

history.appendTag(level); // apend index to list
}
mainNBT.setTag("History", history); // write list to main NBT

 

The NBTTagList ships its size.

 

Reading:

NBTTagList history = stats.getTagList("History", 10);
NBTTagCompound level;
for (int lvl = 0; lvl < history.tagCount(); ++lvl)
{
level = (NBTTagCompound) history.getCompoundTagAt(lvl);
...

 

EDIT

Personal note:

If your whole array will look like this: x1, y1, z1, x2, y2, z2, x3, y3, z3, ....    then you know that i*1 is x, i*2 is y, i*3 is z (for i >= 1).

You can use "NBTTagIntArray" - will be a bit smaller and faster, but whatever, reading/writing is done once in a while so you might aswell not bother.