swing - Strange behavior of java game loop -

i have simple game loop in java:

public void run(){     while(running){         start = system.nanotime();         gamepanel.update();         gamepanel.repaint();         elapsed = system.nanotime() - start;         wait = (target_time - elapsed) / 1000000;         if(wait < 0){wait = target_time;}         try {thread.sleep(wait);}catch(exception e) {e.printstacktrace();}     } } 

now problem: when add sysout in update() outing "updating" , 1 in paintcomponent() outing "repainting", following result:

updating updating updating updating updating (x1000 , more) repainting 

so when repaint 1 time, game updating 1000 , more times. normal? think abit strange, isnt it? example can 1000 steps player until game painting it... means, update() method doesnt wait repaint finishing? why?

thank you!

edit: here update code:

public void update(){     if(moveup){         changemapy(map, -map.getspeed());     }     if(movedown){         changemapy(map, map.getspeed());     }     if(moveright){         changemapx(map, map.getspeed());     }     if(moveleft){         changemapx(map, -map.getspeed());     } } 

edit 2: , changemap does: (maybe problem?)

public void changemapx(map map, int amount){     for(int = 0; < blocks.length; i++){         for(int j = 0; j < blocks[0].length; j++){             blocks[i][j].addx(amount);         }     }     map.addoffsetx(amount); }  public void changemapy(map map, int amount){     for(int = 0; < blocks.length; i++){         for(int j = 0; j < blocks[0].length; j++){             blocks[i][j].addy(amount);         }     }     map.addoffsety(amount); } 

you calculate wait in seconds. (nano-seconds / 1 million)

the parameter sleep should in miliseconds. change line:

wait = (target_time - elapsed) / 1000;