arraylist - Garbage collector not working in java? -

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• why java program taking memory? 3 answers

i have simple program saves screenshots arraylist - example take 100 screenshots, add them list , clear list. this:

public static void main(string[] args) {     jframe frame = new jframe(); // creating simple jframe     frame.setdefaultcloseoperation(jframe.exit_on_close);     frame.setvisible(true);      list<bufferedimage> list = new arraylist<>();     (int = 1; <= 100; i++) {         bufferedimage capture = makescreenshot();         list.add(capture);         system.out.println("capture saved arraylist " + i);     }     list.clear(); } 

and method makescreenshot:

private static bufferedimage makescreenshot() {     robot robot = null;     try {         robot = new robot();     } catch (awtexception e) {         e.printstacktrace();     }     toolkit toolkit = toolkit.getdefaulttoolkit();     rectangle screenbounds = new rectangle(toolkit.getscreensize());     bufferedimage capture = robot.createscreencapture(screenbounds);     return capture; } 

if run simple program, task manager (windows) shows program uses 1gb of ram. why java garbage colllector doesn't remove bufferedimages ram memory? there no references these bufferedimages, right?

i agree durron597, question have answer already. and, said, can't give program less memory needs complete cycle of screen capturing, processing , list clearing.

as stated in accepted answer, the jvm use memory can, , that's ok.

your program stabilize memory usage @ point , run forever. did try that, (not forever though).

but liked lower heap size version of test - how set up:

this how memory used after that:

and it's running 6 hours (almost 700k screenshots taken!):

so, if really need to, can still limit memory usage - have to?

from javadocs: "calling gc method suggests java virtual machine expend effort toward recycling unused objects in order make memory occupy available quick reuse."

so, system.gc() suggestion - , might really bad one.