Solved Chance of drop in double?

Hello.

I want to make a drop chance in double, for example 0.01%. Here is what i have for now, and it works with chance in int:

Code:java

@EventHandler
    public void onEntityDeath(EntityDeathEvent event) {
        if (event.getEntity().getKiller() instanceof Player) {
            if (event.getEntity().getType() == EntityType.SKELETON) {
                Skeleton skeleton = (Skeleton)event.getEntity();
                if (skeleton.getSkeletonType().equals(SkeletonType.WITHER)) {
                    event.getDrops().clear();
                    double chance = Main.plugin.getConfig().getDouble("wither-skeleton-head-drop-chance");
                    Random r = new Random();
                    int n = r.nextInt(100) + 1;
                    if (n <= chance) {
                        event.getDrops().add(new ItemStack(Material.SKULL_ITEM, 1, (short)1));
                    }
                }
            }
        }
    }

How to do this?

Sorry for any mistakes, English is not my native language.

 

Take a look at Math.random()

 

@Max8801

Code:java

double chance = Main.plugin.getConfig().getDouble("wither-skeleton-head-drop-chance");
if (Math.random() <= chance) {
    event.getDrops().add(new ItemStack(Material.SKULL_ITEM, 1, (short)1));
}

Thank's for response, did I understand it correctly?

 

It depends: Is the value you enter in the config a percentage or a probability value?

EDIT:
Examples:
If the percentage was 50%, the corresponding probability value would be 0.5
If the probability value was 1, the corresponding percentage would be 100%

 

@Max8801
The value is "0.003" or "0.01" (i want to do the same thing for other mob), i want it to work as a percentage chance, if the drawn percentage number is smaller, or the same as defined, or 0.01% to 100%. I don't know, how to explain this better.

 

Alright, let's see:
If you want to put a percentage value into your config (e.g. skeletonDropChance: 50), then you have to either devide that config value through 100 or multiply the random value returned by the Math class with 100, because Math.random() returns a value between 0 and 1.

Example:

config:

Code:

# Value in percent
Chances:
  skeleton: 50.0

check:

Code:java

 
if(getConfig().getDouble("Chances.skeleton") >= Math.random() * 100) {
  // Do stuff
}
 

 

@Max8801
OK, thanks, this works if defined chance is at least 1%, but what if I want it to be smaller than 1%, for example 0.01%?

 

This ought to work for values below 1%. Why shouldn't it?

 

@Max8801
Hmm... If i set the config value below 1%, the item is dropped every time.

 

@Max8801
Your math is wrong. The value in the config should be greater than or equal to, not less than.

@MrAndeos
Change the '<' to a '>'

 

Thanks @Zombie_Striker . I guess I copied it wrongly from above.

 

@Zombie_Striker @Max8801
Thanks, looks like it's working now.