CCNA, CCNP, MCSA, CCNA Final Exam, All Answer Test Module With 100/100

The Mystery In exploring precisely which characters were permitted in Java identifiers, I have stumbled upon something so extremely curious that it seems nearly certain to be a bug. I’d expected to find that Java identifiers conformed to the requirement that they start with characters that have the Unicode property ID_Start and are followed by those with the property ID_Continue , with an exception granted for leading underscores and for dollar signs. That did not prove to be the case, and what I found is at extreme variance with that or any other idea of a normal identifier that I have heard of. Short Demo Consider the following demonstration proving that an ASCII ESC character (octal 033) is permitted in Java identifiers: $ perl -le 'print qq(public class escape { public static void main(String argv[]) { String var_\033 = "i am escape: \033"; System.out.println(var_\033); }})' > escape.java $ javac escape.java $ java escape | cat -v i am escape: ^[ ...

There are number of performance tips made obsolete by Java compiler and especially Profile-guided optimization . For example, these platform-provided optimizations can drastically (according to sources) reduces the cost of virtual function calls. VM is also capable of method inlining, loop unrolling etc. What are other performance optimization techniques you came around still being applied but are actually made obsolete by optimization mechanisms found in more modern JVMs?

What is the rationale behind making this kind of code valid in java? Does it exist for some particular reason or is it just a byproduct of other Java language design decisions? Can't you just use the consructor to achieve the same effect? class Student { { System.out.println("Called when Student class is instantiated."); } }

I was assuming LinkedList.Clear() was O(1) on a project I'm working on, as I used a LinkedList to drain a BlockingQueue in my consumer that needs high throughput, clearing and reusing the LinkedList afterwards. Turns out that assumption was wrong, as the (OpenJDK) code does this: Entry<E> e = header.next; while (e != header) { Entry<E> next = e.next; e.next = e.previous = null; e.element = null; e = next; } This was a bit surprising, are there any good reason LinkedList.Clear couldn't simply "forget" its header.next and header.previous member ?

Yet another LanguageX vs LanguageY question.... Currently I have a bunch of apps built on playframework . For the most part I love it. Moving from PHP a few years ago was almost a religious experience -- an actual functional orm, much less boiler plate code, stuff just worked, etc. I still have a website running on a a shared hosting service thats built with PHP+ CodeIgniter . Recently I've been adding some features to this site and have been thinking about porting it to either Ruby on Rails or Playframework. So far though, nothing about rails has really blown me away. It seems like it has pretty much the same featureset as playframework. I like ruby's terseness, and things like blocks, but again for the most part there's been nothing about the language itself that has made me go "oh wow this is 1000x better than java/php/c/whatever!" In fact, some parts actually kind of rub me the wrong way -- I prefer strongly-typed languages for example. My questio...

I'm curious to know, what people here think about using org.apache.commons.lang.builder EqualsBuilder/HashCodeBuilder for implementing the equals/hashcode? Would it be a better practice than writing your own? Does it play well with Hibernate? What's your opinion?

Observe the following program written in Java (complete runnable version follows, but the important part of the program is in the snippet a little bit further below): import java.util.ArrayList; /** A not easy to explain benchmark. */ class MultiVolatileJavaExperiment { public static void main(String[] args) { (new MultiVolatileJavaExperiment()).mainMethod(args); } int size = Integer.parseInt(System.getProperty("size")); int par = Integer.parseInt(System.getProperty("par")); public void mainMethod(String[] args) { int times = 0; if (args.length == 0) times = 1; else times = Integer.parseInt(args[0]); ArrayList < Long > measurements = new ArrayList < Long > (); for (int i = 0; i < times; i++) { long start = System.currentTimeMillis(); run(); long end = System.currentTimeMillis(); long time = (end - start); System.out.printl...