java - Copying Array from ArrayList Element -

i'm building java based game in swing, grid of jbuttons

i have object called cell, custom jbutton additional parameters storing objects. game grid represented cell[][]

i have arraylist of type cell[][] allow me store state of gamegrid after each move. if want undo move, need copy last element of arraylist game grid allow displayed on ui.

my gamegrid panelholder , arraylist moveholder.

so far i've tried collections.copy(panelholder, moveholder.get(moveholder.size())); not compile due "arguments not being applicable type cell[][]"

i've tried system.arraycopy(moveholder.get(moveholder.size()-1), 0, panelholder, 0, panelholder.length);, throws , out of bounds exception. thought due moveholder.size()-1, moveholder.size() has same problem.

i've found numerous questions on stackoverflow , others both show these 2 ways of doing it, can't seem work. there more obvious i'm missing? full class method below:

 public class undoclass implements movecommand{      public arraylist<cell[][]> moveholder = new arraylist<cell[][]>();      public cell[][] execute(cell[][] panelholder) {         if (moveholder.size() > 0){             collections.copy(panelholder, moveholder.get(moveholder.size()));                    if (moveholder.size() > 0){                 moveholder.remove(moveholder.size());             }         }         system.out.println("move undone. undos available:" + moveholder.size());         return panelholder;     }     public void addmove(cell[][] panelholder){         moveholder.add(panelholder);     }      public arraylist<cell[][]> getmoves(){           return moveholder;     } } 

cell class

public class cell extends jbutton {      int co_x = 0;     int co_y = 0;       arraylist<players> current = new arraylist <players>();  } 

if (moveholder.size() > 0) {     (int = 0; < panelholder.length; i++) {         panelholder[i] = moveholder.get(moveholder.size()-1)[i].clone();        }     moveholder.remove(moveholder.size()-1); } 

try this. need make copies of each internal array when copying 2d arrays.