Choosing players based on ArrayList size

Hello bukkit, I am trying to figure out how to select random players based on an ArrayList's size. So say for every 10 elements in the arraylist, 1 player is chosen. Also, what if the number was like 7 or 13, how would I round it to the closest multiple of 10?

Thanks!

 

ShadowLAX
If you want the closest: (array.size() + 5) / 10
With 15 you will get 2.
For the random player, get the list of onlinplayers, create a random number and get the player at the random index.

 

Tarestudio thanks, that helps a bit. What I need though with the players being picked is that with the number from the (array.size() + 5) / 10, which is 2, it would choose that number of random players. so say the number chose was 7, it would choose 7 random people.

 

here is an example i use

int random = new Random().nextInt(Main.classes.size());
Player player = Main.classes.get(random);
p.teleport(player.getLocation());

 

ShadowLAX
Like this?

Code:java

Player[] players = Bukkit.getOnlinePlayers();
Set<Player> result = new HashSet<Player>();
while ( result.size() < ((array.size() + 5) / 10) ) {
  int random = new Random().nextInt(players.length);
  result.add(players[random]);
}

 

I would use the Random bevore choosing the players.

Code:java

Player[] players = Bukkit.getOnlinePlayers();
Player[] result = new Player[(int)((players.length+5)/10)];
Set<Integer> picked = new HashSet<>();
Random r = new Random();
 
for(int i = 0; i<result.length; i++){
   int pick = r.nextInt(players.length);
   for(int p : picked)
        if(p == pick)
            continue;
   result[i] = players[pick];
   picked.add(pick);
}[/i]

 

CoderCloud
This will fail on choosing multiple times the same the player, your for-loop increments everytime, no matter a player was added or not.

Code:java

Player[] players = Bukkit.getOnlinePlayers();
Player[] result = new Player[(int)((players.length+5)/10)];
Set<Integer> picked = new HashSet<>();
Random r = new Random();
 
for(int index = 0; index < result.length && index < player.length; index++){
int pick = r.nextInt(players.length);
while ( picked.contains(pick) ) {
pick = r.nextInt(players.length);
}
result[index] = players[pick];
picked.add(pick);
}