How do I give an item a effect?

[Nieue]

Hello, I've been trying to make an item so that when you hold it in your hand it gives you blindness.

But, when I have the code set up like this (in the class of that item):

@Override
    public void onUpdate (ItemStack stack, World world, Entity entity, int par4, boolean par5)
    {
        super.onUpdate(stack, world, entity, par4, par5);
        if (entity instanceof EntityPlayer)
        {
            EntityPlayer player = (EntityPlayer) entity;
            ItemStack equipped = player.getCurrentEquippedItem();
            if (equipped == stack)
            {
                player.addPotionEffect(new PotionEffect(Potion.blindness.id, 1, 3));
            }
        }

It only gives me this in-game:

And the only effect it gives me is that I am unable to sprint...

 

Can someone help me?

[WorldsEnder]

The second parameter is in ticks I believe. Try something higher like 20 (which should correspond to ~1s).

player.addPotionEffect(new PotionEffect(Potion.blindness.id, 20, 3));//1 replaces with 20

[DrOlive]

I'm not sure, but it might be because in this line:

player.addPotionEffect(new PotionEffect(Potion.blindness.id, 1, 3));

In the second parameter you wrote 1. The second parameter is for the duration, so you wrote it gives the player a blindness effect for one second, which probably isn't even long enough to show the actual blindness effect. Again I'm not completely sure, but hopefully this helps!

[Nieue]

The second parameter is in ticks I believe. Try something higher like 20 (which should correspond to ~1s).

player.addPotionEffect(new PotionEffect(Potion.blindness.id, 20, 3));//1 replaces with 20

Thanks, that did it

[WorldsEnder]

Always glad to help out.