求助（Java画板上不断圆时出现"AWT-EventQueue-0" java.lang.IndexOutOfBoundsException: ）

for( int i = 0 ; i < ga.pl.size(); i ++){
if( 1 == ga.location[ga.pl.get(i).getX()/6][ga.pl.get(i).getY()/6]){
         /*其他代码主要是这一行
          */
         if( 1 == ga.location[ga.pl.get(i).getX()/6][ga.pl.get(i).getY()/6]){
new                                      Circle(ga.pl.get(i).getX(),ga.pl.get(i).getY(),6,Color.GREEN).draw(g);
}
}
}
Exception in thread "AWT-EventQueue-0" java.lang.IndexOutOfBoundsException: Index: 2, Size: 2
at java.util.ArrayList.RangeCheck(ArrayList.java:547)
at java.util.ArrayList.get(ArrayList.java:322)
at ga.ShowPlantBoard.paint(ShowPlantBoard.java:52)
at sun.awt.RepaintArea.paintComponent(RepaintArea.java:248)
at sun.awt.RepaintArea.paint(RepaintArea.java:224)
at sun.awt.windows.WComponentPeer.handleEvent(WComponentPeer.java:310)
at java.awt.Component.dispatchEventImpl(Component.java:4706)
at java.awt.Component.dispatchEvent(Component.java:4460)
at java.awt.EventQueue.dispatchEvent(EventQueue.java:599)
at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:269)
at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:184)
at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:174)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:169)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:161)
at java.awt.EventDispatchThread.run(EventDispatchThread.java:122)
    我在初始化时pl.size()长度是40，在后来程序不断运行，pl.size()长度会不断增加，需要在相应的位置上画圆。当长度大于40时就会出现这个异常。
     求助！！！这个该怎么解决谢谢！！感激不尽。。