# Prevent one Processing window from closing others

**URL:** <https://discourse.processing.org/t/prevent-one-processing-window-from-closing-others/13719>\
**Category:** Coding Questions\
**Created:** [August 31, 2019, 10:54am UTC](https://discourse.processing.org/t/prevent-one-processing-window-from-closing-others/13719 "2019-08-31T10:54:29Z")\
**Posts on this page:** 1\
**Showing post:** 5

<div class="post-metadata">

**Author:** ![micycle](https://yyz2.discourse-cdn.com/flex036/user_avatar/discourse.processing.org/micycle/32/201_2.png) [@micycle](https://discourse.processing.org/u/micycle)\
**Post date:** [August 31, 2019, 7:11pm UTC](https://discourse.processing.org/t/prevent-one-processing-window-from-closing-others/13719/5 "2019-08-31T19:11:36Z")

</div>

_I’ve done some digging – inspired by @GoToLoop and @quark – and have found a solution._

Closing sketches in `P2D` and `JAVA2D` renderer modes calls the PApplet instance’s `exitActual()` method, which contains the line `System.exit(0)` – a static method – which terminates the currently running Java virtual machine.

Overriding `exitActual()` with nothing (i.e. preventing the call to `System.exit(0)`) prevents sketches from closing others, fixing the issue, but introduces another problem in the case of `P2D` sketches: the window is not disposed properly when the cross is clicked.

**Solution:**

_Override `exitActual()` to prevent the JVM (and all sketches) closing when one sketch is closed._

```auto
@Override
public void exitActual() {
}

```

_Introduce the following code (suitable in `setup()`) such that `P2D` sketches are disposed properly:_

```auto
if (getGraphics().isGL()) {
		final com.jogamp.newt.Window w = (com.jogamp.newt.Window) getSurface().getNative();
		w.setDefaultCloseOperation(WindowClosingMode.DISPOSE_ON_CLOSE);
}

```

* * *

**However** , in overriding (preventing) the call to `System.exit(0)`, another issue is introduced: even after all sketches (windows) are closed, the JVM will continue to run in memory. Ideally `System.exit(0)` should be called but only when the last remaining window is disposed.

I propose a rudimentary fix below – a simple counter – but I wonder whether it is possible to inspect the JVM to see the number of live instances of JavaFX/NEWT/AWT windows, using those values instead?

```auto
@Override
public void exitActual() {
	if (Benchmark.n == 1) {
			System.exit(0);
	}
	Benchmark.n--;
}

```

```auto
public class Benchmark {

	public static int n = 3;

	public static void main(String[] args) {

		Sketch sketch1 = new Sketch(PApplet.FX2D);
		Sketch sketch2 = new Sketch(PApplet.P2D);
		Sketch sketch3 = new Sketch(PApplet.JAVA2D);
		PApplet.runSketch(new String[] { "--location=760,0", "" }, sketch1);
		PApplet.runSketch(new String[] { "--location=760,80", "" }, sketch2);
		PApplet.runSketch(new String[] { "--location=760,160", "" }, sketch3);
	}
}

```

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