Re: a tight game loop in Swing

From:

Daniel Pitts <newsgroup.nospam@virtualinfinity.net>

Newsgroups:

comp.lang.java.gui

Date:

Thu, 07 Jun 2012 09:20:55 -0700

Message-ID:

<Ix4Ar.4713$At.4582@newsfe23.iad>

On 6/6/12 11:58 PM, Lew wrote:

Knute Johnson wrote:

Lew wrote:

John B. Matthews wrote:

This reminds of an example adduced by Knute Johnson:

<https://groups.google.com/d/msg/comp.lang.java.gui/aBy_DZFvg2M/-T9aWOwBM-QJ>

Ten points for using the word "adduced".

There are some EDT violations in the cited code's 'main()' routine.

Here's the updated code with that fixed.

import java.awt.*;
import java.awt.event.*;
import java.awt.geom.*;
import java.awt.image.*;
import java.lang.reflect.*;
import javax.swing.*;

public class test3 extends JPanel implements Runnable {
volatile BufferedImage bi;
volatile long then;

I am curious what motivated the choice of 'volatile'.

In my own case I will sometimes speculatively use 'volatile' to mark
fields not essential to state despite that the class does not implement
'Serializable'. While this violates the rigid rule prohibiting
superfluity, I aver that the marker aids reasoning about the state in
such cases.

This doesn't seem to be that.

Volatile has nothing to do with Serializable. Perhaps you're having a
moment of confusing volatile with transient? Volatile is necessary when
you want to force a happens-before relationship to reads/writes to a
field. It also guarantees the you won't have a situation where writes
aren't flushed to main memory before the next attempted read.

In other words, it is one safe way to publish a value across threads.