java - dealing with multiple player thread and repainting -

i working on java bomber-man game, game works fine have concurrent modification exception thrown repeatedly. in game have 2 players , each have own thread run (thread.run()) @ constant 60fps using timer. tried having repainting run after bother thread run @ end of each player run method.

method 1:

public void loop(){  if(!gameover){   player1_thread.run(); //run player 1 thread   player2_thread.run(); //run player 2 thread   gui.repaint() //repaint panel  } 

method 2:

public class player extends character{ //character implements runnable ... @override public void run(){  play();  ...  game.render(); } 

both of these method throws concurrent modification expected how can avoid error other doing:

player1.run(); //call run method of each player class player2.run(); 

which gives player1 advantage.

edit:

method 4:

import java.util.timer  public class player extends character { //character implements runnable     private timer gametimer  @ovveride public void run(){     gametimer.scheduleatfixedrate(new timertask(){          @override         public void run() {             play();             ...             game.render();         }       }, 0, 1000/60); }  public class game extends abstractgame {       private void init(){         ...         thread player1_thread = new thread(player1);         thread player2_thread = new thread(player2);         gui = new gamegraphics(this); //subclass of jpanel         player1_thread.start();         player2_thread.start();     }  /* method called @ constant 60fps(like player timer) in main game timer in abstract game class */     public void gameloop(){         if(!gameover){             render();         ...         }      } 

this throws exception

wrong : calling run() execute instructions using main thread.

correct: call player1.start() start new thread, run() {...} executed in newly started thread.