[1.7.2] Chest - Generation - Filling up the spawned chest with items[HELP NEEDE]

Hi,

I need help with Chests.

I have generation that spawns chest and all working great. Now my problem is that i dont want my chest to get RANDOM items inside of it i want 3 items no more not less and not random 3 items, that i want to have inside.

My current code: ( set for random, i dont know how to change it that 3 items that i want to spawn inside )

 
par1World.setBlock(x +5, y -6, z +5, Blocks.chest, 0, 2);
        	TileEntityChest bigchest1 = (TileEntityChest)par1World.getTileEntity(par3 +5, par4 -6, par5 +5);
        	if(bigchest1 != null)
        	{
        	for(int i = 0; i< par2Random.nextInt(bigchest1.getSizeInventory()); i++)
        	{
        	bigchest1.setInventorySlotContents(par2Random.nextInt(bigchest1.getSizeInventory()), pickRandomItemChest(par2Random));
        	}

private ItemStack pickRandomItemChest(Random rand) {

    int i = rand.nextInt(3);

    if(i == 0)

    {

    return new ItemStack(Items.coal, rand.nextInt(30));

    }

    if(i == 1)

    {

    return new ItemStack(Items.diamond, 1);

    }

    if(i == 2)

    {

    return new ItemStack(Items.emerald, 1);

    }

    return new ItemStack(Items.gold_ingot, 1);

    }