eclipse - Why is there a java.lang.NullPointerException when referencing Image from a different class? -

i creating clone of breakout pc, earlier tonight found there nullpointerexception being thrown , shown in console. oddly, method run() told catch exceptions occour , show stacktrace , ignore them, time freezes game @ start, int log, keypresses still tracked, nothing happens in-game. obviously, game didn't abort, not repaint.

it seems coming 1 line of code:

 if (by >= bricks[0].y && <= bricks[0].y + bricks[0].img.getheight(null) && bx >= bricks[0].x && bx <= bricks[0].x + bricks[0].img.getwidth(null)) { 

here log , stacktrace (the entire thing):

game starting, menu boot. menu loaded, jframe visible. running thread. play clicked, start game initialization. creating jframe. jframe created , visible. starting game thread initialize user variables. initialized user variables. initialization complete, start game. java.lang.execption in line 86/87, class game. stacktrace: java.lang.nullpointerexception     @ game.move(game.java:195)     @ game.run(game.java:86)     @ java.lang.thread.run(thread.java:722) space hit! key arrowleft hit. key arrowleft hit. key arrowleft hit. key arrowleft hit. key arrowleft hit. key arrowleft hit. key arrowleft hit. key arrowleft released. key escape hit! 

i hope problem can solved.

lets @ "line":

   if (by >= bricks[0].y &&         <= bricks[0].y + bricks[0].img.getheight(null) &&         bx >= bricks[0].x &&         bx <= bricks[0].x + bricks[0].img.getwidth(null)) { 

assuming bx, by, , x , y fields primitive types (e.g. int), here's list of things could result in npe:

• the bricks variable null
• the zeroth element of bricks null
• the value of bricks[0].img null

if bx, by, x and/or y wrapper type, 1 of null. lead npe when unboxing value.

it not caused passing null getheight or getwidth methods, because 1) believe valid , 2) if wasn't npe thrown in different place stacktrace shows.

(i can't tell if passing null in calls correct ... either way, not cause of npe based on evidence have provided.)

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if want figure actually causing problem, debug code or add traceprints test of things null null.