java - Can't add to an array list -

i have oddest problem, simple solution.

i have created , initialized list , proceeded create 4 objects of list's type. in constructor of these place in list. or @ least supposed to. out of bound exception , cant figure out why. set list have size of 402 (for possible vk values) in console , debug says has size 0, no matter how large or empty set too....

public class inputhandler implements keylistener {  public static list<key> keylist = new arraylist<key>(keyevent.key_last);  public key = new key(keyevent.vk_up); public key down = new key(keyevent.vk_down); public key left = new key(keyevent.vk_left); public key right = new key(keyevent.vk_right);   public class key     {      public int keycode;      public key(int defaultcode)     {         this.keycode = defaultcode;         keylist.add(keycode,this);     }      public key remapkey(int newkey)     {         keylist.remove(keycode);         keylist.set(newkey, this);         this.keycode = newkey;         return this;     }  }  } 

there more code attempted sscce it.

the info of value console this:

exception in thread "roguelovemainthread" java.lang.indexoutofboundsexception: index: 38, size: 0 

much apologies stupidity

you've created new arraylist capacity of 402, it's still got size of 0 after constructor call. docs of constructor call you're using:

public arraylist(int initialcapacity)

constructs empty list specified initial capacity.

parameters:
initialcapacity - initial capacity of list

and docs of arraylist itself:

each arraylist instance has capacity. capacity size of array used store elements in list. @ least large list size. elements added arraylist, capacity grows automatically.

the capacity not size.

so, options:

• populate list null entries until have got size want
• use array instead of list (after all, need fixed size, right?)
• use map<integer, key> instead