Episode 26. I take Exception to that statement! A quick overview of Exception quirkiness

As developers, we have to deal with Exceptions every day (or at least every other day). In this episode we dive a bit on exception (and exception handling), plus we talk about certain behaviors that are not so well-understood (try returning from a finally block, or why exception stack traces sometimes misteriously disappears). A good review for those who already know, and a great primer for those diving into Exceptions, this episode is sure to show some surprises!


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Tweet, Tweet! (https://twitter.com/#!/fguime) Try-with-resources construct http://docs.oracle.com/javase/tutorial/essential/exceptions/tryResourceClose.html
Exception Definition http://docs.oracle.com/javase/tutorial/essential/exceptions/definition.html
Checked vs Unchecked Exceptions Debatehttp://www.ibm.com/developerworks/java/library/j-jtp05254/index.html
More Exception Debates from C vs C++, still a useful read. http://www.250bpm.com/blog:4
Vote for us in iTunes (http://itunes.apple.com/us/podcast/java-pub-house/id467641329)
Questions, feedback or comments! comments@javapubhouse.com
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ITunes link (http://itunes.apple.com/us/podcast/java-pub-house/id467641329)
Java 7 Recipes book! (http://www.amazon.com/gp/product/1430240563/ref=as_li_ss_il?ie=UTF8&tag=meq-20&linkCode=as2&camp=1789&creative=390957&creativeASIN=1430240563)
Hey! if you like what you hear, treat me a beer! (It's the Java pub house after all :) https://www.paypal.com/cgi-bin/webscr?cmd=_s-xclick&hosted_button_id=Z8V2ZWV93UMW4

Episode 25. Reflection and vampire classes, and compiling Java from within Java.

We have heard the word "Reflection" thrown around, what does it mean? it is a new Twilight series? is it about Vampires? In all, we shed sunlight into what reflection is (and more importantly why in the world you want to use it). And also cover a technique to compile and load programs within your program. Javascript guys had access to this by doing eval("your program here"), and while Java doesn't have an eval function, there are ways of achieving similar results (and very specific reasons to do this crazy technique. Mostly performance)

It's SUMMER! If you like what you hear, DEFINITIVELY, treat me a beer ! :) (It's the Java pub house after all :) https://www.paypal.com/cgi-bin/webscr?cmd=_s-xclick&hosted_button_id=Z8V2ZWV93UMW4

Nimbus code to get the dang CacheMode (considered a private variable)

public class ButtonPainter extends AbstractRegionPainter {
    public ButtonPainter() {

        Class<?> c = null;
        PaintContext ctx = new PaintContext(new Insets(0,0,0,0), new Dimension(100,100), false, null, Double.POSITIVE_INFINITY, 2.0 );

        try {
            c = Class.forName("javax.swing.plaf.nimbus.AbstractRegionPainter$PaintContext$CacheMode");
        } catch (ClassNotFoundException e) {
            e.printStackTrace();
        }
        if (c != null) {
            Object cacheMode = c.getEnumConstants()[2];   // NINE_SQUARE_SCALE
            for (Field field : ctx.getClass().getDeclaredFields()) {
                if (c.getName().equals(field.getType().getName())) {        // if Field is the CacheMode
                    try {
                        // the following lines would not be necessary for example if
                        // AbstractRegionPainter.cacheMode were protected or public.

                        field.setAccessible(true);                          // make it accessible so that we can set it
                        field.set(ctx, cacheMode);                          // set the cachemode
                        // this is equivalent as sayin "ctx.cacheMode = CacheMode.NINE_SQUARE_SCALE" if it were public/protected
                        break;
                    } catch (IllegalAccessException e) {
                        e.printStackTrace();
                    }
                }
            }
        }

    }

    @Override
    protected PaintContext getPaintContext() {
        return null;  //To change body of implemented methods use File | Settings | File Templates.
    }

    @Override
    protected void doPaint(Graphics2D g, JComponent c, int width, int height, Object[] extendedCacheKeys) {
        //To change body of implemented methods use File | Settings | File Templates.
    }
}

Code to get instance from a source file

    public static Object getInstanceForSource(String className, String sourceForRule) {
        String filename = "tmp/" + className + ".java";
        File file = new File(filename);
        writeFile(filename, sourceForRule);    
        String classPath = System.getProperty("java.class.path");
        String[] args = new String[]{
                "-classpath", classPath,
                filename
        };


        StringWriter compilerOutput = new StringWriter();
        int status = com.sun.tools.javac.Main.compile(args,new PrintWriter(compilerOutput));
        additionalInfo.value = compilerOutput.toString();
        switch (status) {
            case 0:  // OK
                // Make the class file temporary as well
                File classFile = new File("./tmp/");
                try {
                    // Try to access the class and run its main method
                    URLClassLoader loader = new URLClassLoader(new URL[] {classFile.toURI().toURL()});
                    Class clazz = loader.loadClass(className);
                    return clazz.newInstance();
                } catch (Exception ex) {
                    additionalInfo.value = "Exception in main: " + Utilities.exceptionToString(ex)+"\n"+additionalInfo.value;
                }
                break;
            case 1:
                System.out.println ("Status: Error" +"\n"+additionalInfo.value);
                break;
            case 2:
                System.out.println ("Status: CMDERR" +"\n"+additionalInfo.value);
                break;
            case 3:
                System.out.println ("Status: SYSERR" +"\n"+additionalInfo.value);
                break;
            case 4:
                System.out.println ("Status: ABNORMAL" +"\n"+additionalInfo.value);
                break;
            default:
                System.out.println ("Status: UNKNOWN" +"\n"+additionalInfo.value);
                break;
        }
        return null;
    }

    public static void writeFile(String fileName, String content) {
        Writer writer;
        File file = new File(fileName);
        try {
            writer = new BufferedWriter(new FileWriter(file));
            writer.write(content);
            writer.close();
        } catch (IOException e) {
           System.out.println ("I/O exception "+e);
        }
    }

Tweet, Tweet! (https://twitter.com/#!/fguime)
Reflection 'trail' http://docs.oracle.com/javase/tutorial/reflect/index.html
Create dynamic applications with javax.tools http://www.ibm.com/developerworks/java/library/j-jcomp/index.html
URLClassLoaders (loads .class files generated http://docs.oracle.com/javase/6/docs/api/java/net/URLClassLoader.html
Vote for us in iTunes (http://itunes.apple.com/us/podcast/java-pub-house/id467641329)
Questions, feedback or comments! comments@javapubhouse.com
Subscribe to our podcast! (http://javapubhouse.libsyn.com/rss)
ITunes link (http://itunes.apple.com/us/podcast/java-pub-house/id467641329)
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Episode 24. Usability for Engineers. A simple way to achieve usability for the hardcore engineer

Designers will come to you, and say "Hm, I think your program is not as user-friendly". And sometimes, when you ask them to elaborate, they seem to follow a hidden and cryptic ritual. They are right, yet, is hard to see how did they come up with those usability suggestion. Alas, behind every usability magician, there is a magic trick! and on this podcast we reveal in plain sight what makes interfaces usable (and quote a lot from Alan Cooper's book). Once you see the trick, you would never be daunted on spotting usability yourself, and making things much more usable before passing them on. Usability magic for all of us!

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Twitter, twitter, twitter, twitter! (https://twitter.com/#!/fguime)

The immates are running the asylum (Alan Cooper) http://www.amazon.com/The-Inmates-Are-Running-Asylum/dp/0672316498
Don't make me think http://www.amazon.com/Dont-Make-Me-Think-Usability/dp/0321344758/ref=sr_1_1?s=books&ie=UTF8&qid=1336346454&sr=1-1

Vote for us in iTunes (http://itunes.apple.com/us/podcast/java-pub-house/id467641329)

Questions, feedback or comments! comments@javapubhouse.com

Subscribe to our podcast! (http://javapubhouse.libsyn.com/rss)
ITunes link (http://itunes.apple.com/us/podcast/java-pub-house/id467641329)
Java 7 Recipes book! (http://www.amazon.com/gp/product/1430240563/ref=as_li_ss_il?ie=UTF8&tag=meq-20&linkCode=as2&camp=1789&creative=390957&creativeASIN=1430240563)

Hey! if you like what you hear, treat me a beer! (It's the Java pub house after all :) https://www.paypal.com/cgi-bin/webscr?cmd=_s-xclick&hosted_button_id=Z8V2ZWV93UMW4