IndexOutOfBoundsException: Index: 1, Size: 1?

So I picked up the tutorial How To Make a MiniGame and I went off and did my own thing. I have everything I want working, but when I try to remove a specific arena, I get an error on the console "IndexOutOfBoundsException: Index: 1, Size: 1". I've tried to do as much as I can on my own to fix it, but it still isn't working.

This is the error:

PHP:

Caused by: java.lang.IndexOutOfBoundsException: Index: 1, Size: 1
        at java.util.ArrayList.rangeCheck(ArrayList.java:635) ~[?:1.7.0_45]
        at java.util.ArrayList.remove(ArrayList.java:474) ~[?:1.7.0_45]
        at net.mavenpvp.arenas.ArenaManager.removeArena(ArenaManager.java:137)

Line 137 is:

Code:java

list.remove(i);

Pretty much used to remove the arenas id.

But for some reason it gives an error.

Here's some more code if its needed:

Code:java

public void removeArena(int i) {
        Arena a = getArena(i);
        if(a == null) {
            return;
        }
        arenas.remove(a);
 
        Files.Arenas.set("Arenas." + i, null);
        List<Integer> list = Files.Arenas.getIntegerList("Arenas.Arenas");
        list.remove(i);
        Files.Arenas.set("Arenas.Arenas", list);
        Files.saveArenas();   
    }

To remove the arena:

Code:java

if(args[0].equalsIgnoreCase("remove")) {
                        if(player.hasPermission("mavenarenas.arena.remove")) {
                            if(args.length != 2){
                                player.sendMessage("Insuffcient arguments!");
                                return true;
                            }
                            int num = 0;
                            try{
                                num = Integer.parseInt(args[1]);
                            }catch(NumberFormatException e){
                                player.sendMessage("Invalid arena ID");
                            }
                            ArenaManager.getManager().removeArena(num);
 
                            return true;
                        } else {
                            MessageManager.getInstance().msg(player, ChatColor.RED + "You don't have permission!");
                            return true;
                        }
                    }

 

Epicballzy arrays (and thus Lists, since they are based on arrays) start with index 0, not 1.

Thus all valid indices are between 0 and size - 1, which leaves 0 as the only option.

 

fireblast709 So what do you suggest would be the best way to fix this? Would there be some sort of check I would have to do?

 

Just change line 9 to

Code:java

                                num = Integer.parseInt(args[1]) - 1;

and that should fix the issue because arrays start from 0 not 1 like fireblast said.

 

Epicballzy check if i is smaller than size?

 

Another thing you need to watch out for is that you're at risk of having a NumberFormatException by trying to parse the arg to an integer without making sure the string is actually a valid number. As it stands, your code assumes that the player will always enter the correct input which is a very dangerous thing to assume. Your best option is probably to surround the parsing with try/catch brackets so you can properly handle the exception.

Code:java

try
{
num = Integer.parseInt(args[1]) - 1;
} catch (NumberFormatException e)
{
//Do something here like tell the player their input was wrong
}