I'm playing around and trying to make half slabs and stairs to go with my planks. I made the stairs without any problem but the slabs are more complex. I've made the slabs placeable because for 20 minutes that wasn't possible, but I can't them on top of each other. Here's what I have so far.

public static BlockHalfSlab darkwoodslab1;
public static BlockHalfSlab darkwoodslab2;

	darkwoodslab1 = (BlockHalfSlab) new BlockMagicSlab(725, false).setUnlocalizedName("darkwoodslab1").setHardness(3.0F).setResistance(2.0F).setStepSound(Block.soundWoodFootstep);
	LanguageRegistry.addName(darkwoodslab1, "Dark Wood Slab");
	GameRegistry.registerBlock(darkwoodslab1, "darkwoodslab1");
	MinecraftForge.setBlockHarvestLevel(darkwoodslab1, "axe", 1);

	darkwoodslab2 = (BlockHalfSlab) new BlockMagicSlab(726, true).setUnlocalizedName("darkwoodslab2").setHardness(3.0F).setResistance(2.0F).setStepSound(Block.soundWoodFootstep);
	LanguageRegistry.addName(darkwoodslab2, "Dark Wood Double Slab");
	GameRegistry.registerBlock(darkwoodslab2, "darkwoodslab2");
	MinecraftForge.setBlockHarvestLevel(darkwoodslab2, "axe", 1);

darkwoodslab2 is the double slab.

Slab Class

public class BlockMagicSlab extends BlockHalfSlab
{
@SideOnly(Side.CLIENT)
private Icon theIcon;

public BlockCustomSlab(int par1, boolean par2)
{
	super(par1, par2);
	this.setCreativeTab(CreativeTabs.tabBlock);
}

@Override
public Icon getIcon(int par1, int par2)
{
	int k = par2 & 7;

	if (this.isDoubleSlab && (par2 &  != 0)
	{
		par1 = 1;
	}

	return k == 0 ? (par1 != 1 && par1 != 0 ? this.theIcon : this.blockIcon) : (k == 1 ? MagicElementsMod.darkwoodplanks.getBlockTextureFromSide(par1) : this.blockIcon);
}

@Override
public void registerIcons(IconRegister par1IconRegister)
{
	this.blockIcon = par1IconRegister.registerIcon("ModClass.modid:darkwoodslabtop");
	this.theIcon = par1IconRegister.registerIcon("ModClass.modid:darkwoodslabside");
}

@Override
protected ItemStack createStackedBlock(int par1)
{
	return new ItemStack(MagicElementsMod.darkwoodslab1.blockID, 2, par1 & 7);
}

@Override
public int idDropped(int par1, Random par2Random, int par3)
{
	return MagicElementsMod.darkwoodslab1.blockID;
}

@Override
public void getSubBlocks(int par1, CreativeTabs par2CreativeTabs, List par3List)
{
	if (par1 != MagicElementsMod.darkwoodslab2.blockID)
	{
		for (int j = 0; j <= 1; ++j)
		{
			if (j != 1)
			{
				par3List.add(new ItemStack(par1, 1, j));
			}
		}
	}
}
}

In the getSubBlocks Method I had to change j <= 7; because seven of the same slabs were showing up in the creative tab.

Anyone know how to fix this?

Yes, the main issue is you can't read code. Please, learn.

 

@Override
protected ItemStack createStackedBlock(int par1)
{
	return new ItemStack(MagicElementsMod.darkwoodslab1.blockID, 2, par1 & 7);
}

Look at the ItemStack you are giving here.

 

didn't fix it sooo. I made that class according to the blockstep class which says exactly

 

    protected ItemStack createStackedBlock(int par1)

    {

        return new ItemStack(Block.stoneSingleSlab.blockID, 2, par1 & 7);

    }

 

What about this :

protected ItemStack createStackedBlock(int par1)

    {

        return new ItemStack(Block.stoneSingleSlab.blockID, 2, par1 & 7);

    }

Well it's the itemID & itemDamage.

Well I'm still confused on how to solve the double slab problem if anyone could help me out a bit more.