Solved How i create a probability in bukkit?

Hi guys
When i hit a player i would like that he has a chance to be poisonous (25%) and 75% of nothing happens.
In my code when i hit a plyer he will be poisonous.
So the question is how i create a probability?

Code

Code:

    @EventHandler
    public void  onHit(EntityDamageByEntityEvent event) {
       
        if (event.getDamager() instanceof Player) {
           
            Player damager = (Player) event.getDamager();
               
               player.addPotionEffect(new PotionEffect(PotionEffectType.POISON, 20*5, 1 );
           
        }
       
    }

Thank you!

 

@Gonmarte
Although not technically a bukkit question, as probability is more Java oriented, but the following method should work.

Code:

    public static boolean percentChance(double percent){
        if(percent > 100 || percent < 0){
            throw new IllegalArgumentException("Percentage cannot be greater than 100 or less than 0!");
        }
        double result = new Random().nextDouble() * 100;
        return result <= percent;
    }

Just input the percent (a number between 0 and 100), and receive a Boolean decider.

 

@meguy26
I didnt understand at all...
First we are check if the percent if more then 100 or less then 0 and we are saying then its impossible it happens.
Then i didnt understand the variable double result = newRandom().nextDouble() * 100;
return result <= result;
What is the mean for this variable? why the number 100?
Thank you!

 

@Gonmarte

@meguy26's reply is a method that will return "true" based on the percentage given in the argument.
For example, if you put 75.0 as the argument:
- the method "new Random().nextDouble()" returns a double value between 0.0 and 1.0, hence the need to multiply the value by 100. "result" will have a random value between 0.0 and 100.0.
- then check if the result (random value) is lower or equal than the given percentage of probability.

That sums it up.

 

@Gonmarte
Activating commented code operation:

Code:

   public static boolean percentChance(double percent){
        if(percent > 100 || percent < 0){ //If the percent is greater than 100, than its always true, if its less than 0, than its always false, this check can be removed if you wish
            throw new IllegalArgumentException("Percentage cannot be greater than 100 or less than 0!");
        }
        double result = new Random().nextDouble() * 100; //Random#nextDouble() generates a double number between 0 and 1, then multiply that by 100 to get a nice percentage
                            //because percentages can be converted from decimals.
        return result <= percent; //You're inputed percent chance (75 for example), will return true when the 'result' is less than or equal to it (75).
                //This may not look like a probability calculation, but it is. Because the random number generated can be ANYWHERE between 0 and 100,
                //it will be less than or equal to 75, 75% of the time.
    }

EDIT:
Yeah what @MOMOTHEREAL said

 

@meguy26
@meguy26 @MOMOTHEREAL
Thank you both =)
I tested the "test plugin" just to see if work and i doesnt work ;/
What is the error?

Code:

public static boolean percentChance(double percent) {
       
        if(percent > 100 || percent < 100) {
           
            throw new IllegalArgumentException("A percentagem nao pode ser maior do que 100 nem menor do que 0");
           
           
           
        }
        double result = new Random().nextDouble() * 100;
       
        return result <= percent;
       
    }
   
    @EventHandler
   
    public void onPlayerHit(EntityDamageByEntityEvent event) {
       
        if(event.getDamager() instanceof Player && event.getEntity() instanceof Player) {
           
            Player damager = (Player) event.getDamager();
           
            if(percentChance(75)) {
               
                damager.addPotionEffect(new PotionEffect(PotionEffectType.SPEED, 20*5, 2));
               
            }
           
        }
       
    }

 

@Gonmarte
What exactly doesn't work? Can we see your main class?

 

@Gonmarte
Are you sure you have registered your Listener class? Try adding some debug lines to see what's not working right.

 

@meguy26 Its just that but here we go :

Code:

package me.gonmarte;

import java.util.Random;

import org.bukkit.Bukkit;
import org.bukkit.entity.Player;
import org.bukkit.event.EventHandler;
import org.bukkit.event.Listener;
import org.bukkit.event.entity.EntityDamageByEntityEvent;
import org.bukkit.plugin.java.JavaPlugin;
import org.bukkit.potion.PotionEffect;
import org.bukkit.potion.PotionEffectType;

public class Main extends JavaPlugin implements Listener{
  
    @Override
    public void onEnable() {
      
        Bukkit.getServer().getPluginManager().registerEvents(this, this);
    }
  
    @Override
    public void onDisable() {
      
      
    }
  
  
    public static boolean percentChance(double percent) {
      
        if(percent > 100 || percent < 100) {
          
            throw new IllegalArgumentException("A percentagem nao pode ser maior do que 100 nem menor do que 0");
          
          
          
        }
        double result = new Random().nextDouble() * 100;
      
        return result <= percent;
      
    }
  
    @EventHandler
  
    public void onPlayerHit(EntityDamageByEntityEvent event) {
      
        if(event.getDamager() instanceof Player && event.getEntity() instanceof Player) {
          
            Player damager = (Player) event.getDamager();
          
            if(percentChance(75)) {
              
                damager.addPotionEffect(new PotionEffect(PotionEffectType.SPEED, 20*5, 2));
              
            }
          
        }
      
    }
}

@MOMOTHEREAL Look u.

EDIT by Moderator: merged posts, please use the edit button instead of double posting.

 

@Gonmarte
Try adding some debug just in case you are checking something wrong:

Code:

@EventHandler
 
    public void onPlayerHit(EntityDamageByEntityEvent event) {
      getLogger().info("An entity was damaged by another entity...");
        if(event.getDamager() instanceof Player && event.getEntity() instanceof Player) {
            getLogger().info("A player was damaged by another player...");
            Player damager = (Player) event.getDamager();
            boolean speed = percentChance(75.0);           

            if(speed) {
                getLogger().info("The probability was met (75%)");
                damager.addPotionEffect(new PotionEffect(PotionEffectType.SPEED, 20*5, 2));
             
            }
        }
     
    }

 

@MOMOTHEREAL I tried ur code and ran a HUGEEEEEEEEE error in the console, but i cant copy it. There is anyway to get it coding?

 

@Gonmarte
What do you mean "can't copy it". Just highlight over the text in the output log, right click, and click "copy". Should be as simple as that.

 

@Gonmarte
You can copy the error by going into the 'logs' folder and finding the one with the error

 

@MOMOTHEREAL @Zombie_Striker

*slams my face into the desk*

 

@mythbusterma What?
@meguy26 logs folder? where is it?

 

Let's think about our code before we write it.

 

@mythbusterma AHHHHHHHHHHHHHHHH kkkkkkkkkkkk
My bad '-' LOL that was funny xD
Ill test it now thank you @mythbusterma for being my eyes!

@mythbusterma @meguy26 @Zombie_Striker @MOMOTHEREAL SOLVE IT! Thank you guys

EDIT by Timtower: merged posts

 

@mythbusterma Darnit, I assumed he copy-pasted the code he was spoonfed... you know, people seem to do that here, usually...