Tech Review: Monday, October 10, 2011

C# null-coalescing operator

http://msdn.microsoft.com/en-us/library/ms173224.aspx

• From C# Reference for VS 2010
• example
• int? x = null;
• int y = x ?? -1;
• string s = null;
• Console.WriteLine (s ?? "Unspecified");
• used to define a default value for a nullable value type
• it returns the left-hand operand if it is not null; otherwise it returns the right operand

http://msdn.microsoft.com/en-us/library/1t3y8s4s.aspx

• more example from C# Programming Guide for VS 2010

http://stackoverflow.com/questions/278703/unique-ways-to-use-the-null-coalescing-operator

• not in Java, but some would like to add the feature

http://blog.joda.org/2009/01/java-7-null-default-and-null-safe_7527.html

• more about not in Java

http://www.merriam-webster.com/dictionary/coalescing

• coalescing mean "to grow together"
• does this sound like a good description of what the operator is doing?

Regions in Java

I know the above picture is not about 'Regions in Java' code, but it looked nice.

http://stackoverflow.com/questions/2344524/java-equivalent-to-region-in-c

• Basically, there are no region pre-compiler directives in Java
• There is support in some IDEs
• NetBeans
• // <editor-fold defaultstate="collapsed" desc="Your Fold Comment">
• ...
• // <editor-fold>
• Eclipse
• does it automatically for methods, imports, etc.
• Not declaration like in NetBeans
• Could you add one?
• Emacs?

Velocity Android 2.0 Internet Table 7" $100

http://www.tigerdirect.com/applications/searchtools/item-Details.asp?EdpNo=7188918&sku=V266-3032

• almost what I want
• missing the camera
• Multi touch capacitive screen

Viewsonic gTablet 10.1" Android 2.2:  $270

http://www.tigerdirect.com/applications/searchtools/item-Details.asp?EdpNo=7212231&sku=V18-0020

• This is what I want except the price and Android version

Simple C# Program

http://www.csharp-station.com/Tutorials/Lesson01.aspx

• the main routine starts with a Capital 'M' in C#
• starts with a lower case 'm' in Java

Listeners and Events (Actions) in Java

http://download.oracle.com/javase/tutorial/uiswing/events/index.html

• lesson on writing event listeners

http://download.oracle.com/javase/tutorial/uiswing/events/intro.html

• action listener
• public class Beeper ... implements ActionListener {
• adding an action listener to something
• button.addActionLisener ( new Beeper() )
• implement the method that does the action
• public void actionPerformed (ActionEvent e) {

http://download.oracle.com/javase/tutorial/uiswing/examples/events/BeeperProject/src/events/Beeper.java

• complete Beeper example

Java Color Map

http://www.ee.columbia.edu/~ronw/code/MEAPsoft/doc/html/ColorMap_8java-source.html

• color map in java
• Copyright
• Carnegie Mellon
• Sun
• Mitsubishi

Java List Interface and ArrayList Class

http://download.oracle.com/javase/6/docs/api/java/util/List.html

• Interface List <E>

http://download.oracle.com/javase/6/docs/api/java/util/ArrayList.html

• Class ArrayList<E>
• Example
• List list = Collections.synchronizedList (new ArrayList(...));

Java Collection Interface and Collections Class

http://download.oracle.com/javase/1,5.0/docs/api/java/util/Collection.html

• Interface Collection<E>

http://download.oracle.com/javase/1.4.2/docs/api/java/util/Collections.html

• static void sort (List list)
• reverse (List list)

Java Queue Interface and PriorityQueue Class

http://en.wikipedia.org/wiki/Queue_(abstract_data_type)

• new elements are put (enqueued) on the back of the queue
• element are pulled (dequeued) from the front of the queue
• First In First Out (FIFO)

http://download.oracle.com/javase/1,5.0/docs/api/java/util/Queue.html

• Interface Queue<E>
• offer (E o) // enqueue
• adds an element to the tail of the queue
• poll () // dequeue
• returns a removed element from the queue
• null is empty

http://download.oracle.com/javase/1,5.0/docs/api/java/util/PriorityQueue.html

• Class PriorityQueue<E>
• boolean add (E o)
• boolean offer (E o)
• E poll ()

Java Map Interface and HashMap Class

http://download.oracle.com/javase/tutorial/collections/interfaces/map.html

• tutorial

http://download.oracle.com/javase/6/docs/api/java/util/Map.html

• Interface Map<K,V>
• V put (K key, V value)
• V get (Object key)

http://download.oracle.com/javase/6/docs/api/java/util/HashMap.html

• Class HashMap<K,V>
• Example:
• Map m = Collections.synchronizedMap (new HashMap (...));

Chrome Remote Desktop

https://chrome.google.com/webstore/detail/gbchcmhmhahfdphkhkmpfmihenigjmpp

• BETA
• allow users to remotely access another computer through the Chrome browser or Chromebook
• An add on
• can easily miss the Icon after installation 

Tech Review: Wednesday, September 21, 2011

Working with porting C# to Java today.

Example of Java enums:  http://javahowto.blogspot.com/2008/04/java-enum-examples.html

• It is sort of like a class because you can override method inside the enum.
• @Override public String toString() {....}

Struct like objects in Java:  

• http://stackoverflow.com/questions/36701/struct-like-objects-in-java
• http://www.javacamp.org/javavscsharp/struct.html
• Java doesn't have structs
• in C# structs are:
• sealed (final)
• lightweight
• a value type, not a reference type (Object)
• more efficient than classes

Java vs. C# page: http://www.javacamp.org/javavscsharp/

• Has lots of really nice and clear comparisons.
• I need to read the whole thing

Benefits of using Final classes in Java:  http://www.java-tips.org/blog/java-se/benefits-of-using-final-class.html

• Control
• no one can inherit 
• final methods run faster than normal methods
• Java compiler may be able to inline a final method
• this link is suppose to dispute that
• http://www.ibm.com/developerworks/java/library/j-jtp1029.html
• 
  

Ternary or conditional operator in Java:  http://www.janeg.ca/scjp/oper/ternary.html

• operand1 ? operand2 : operand3;
• operand1 must be a boolean value or experssion

Operator overloading in Java:  http://stackoverflow.com/questions/77718/java-operator-overload

• program cannot overload operator like '+' or '-'
• http://www.velocityreviews.com/forums/t141181-operator-overloading-in-java.html
• JFront will take overload code and convert it to something Java can compile
• http://www.gginc.biz/jfront/index.html

The C# dictionary is similar to the Java Map interface:  

• http://download.oracle.com/javase/1.4.2/docs/api/java/util/Dictionary.html
• http://stackoverflow.com/questions/687942/java-map-equivalent-in-c
• Show going from Java Map to C# dictionary 
• description of Map interface
• http://download.oracle.com/javase/tutorial/collections/interfaces/map.html

The ArrayList Generic Class in Java:

• http://download.oracle.com/javase/6/docs/api/java/util/ArrayList.html
• Implements in List interface along with others
• not synchronized
• has an example of how to synchronize an ArrayList object

The C# ICollection interface:

• http://msdn.microsoft.com/en-us/library/92t2ye13.aspx
• seems similar to function of the Java Collection interface
• http://download.oracle.com/javase/6/docs/api/java/util/Collection.html

Another C#/Java comparison:  http://www.25hoursaday.com/CsharpVsJava.html#collections

A Java tutorial on collection interfaces:  

• http://download.oracle.com/javase/tutorial/collections/interfaces/
• http://download.oracle.com/javase/tutorial/collections/
• top of tutorial for collections

Today I was confused as to why code would compile in my simple command line program and not in Eclipse.

• Sometimes the error messages in Eclipse are miss leading
• I was trying to write code in the class body outside a method

Some examples of testing for null:  http://www.daniweb.com/software-development/java/threads/156111

• if (child == null) child = new Lista(c, null);

A tutorial on Eclipse:

• http://www.vogella.de/articles/Eclipse/article.html
• perspectives
• a visual container for a set of view and editors
• java
• debug
• C++?
• view and editors are grouped into
• views
• editors
• projects
• located in workspace
• workspace
• physical location of projects
• I thing Eclipse is more complex for many things that NetBeans.
• It's really an SDK, rather than an IDE (NetBeans)
• Seeing the error can be a pain in the neck
• http://stackoverflow.com/questions/1671115/how-to-detect-eclipse-compile-errors-java-jdt
• http://stackoverflow.com/questions/585642/eclipse-3-4-1-how-to-view-compiler-output-in-console-while-building-a-project
• The Eclipse JDT provides its own build-in Java compiler
• tightly integrated with Eclipse and JDT (Java Development Tools)
• http://www.eclipse.org/jdt/
• problems clearing 'Problems' window:  http://stackoverflow.com/questions/2385402/eclipse-cdt-how-to-clear-problems-window-without-invoking-clean-project-or-build
• tried what was recommended, but it didn't work
• no good solution given

Comparing Java and C# Generics:  http://www.jprl.com/Blog/archive/development/2007/Aug-31.html

Java Properties and C# properties are not the same thing at all:  http://download.oracle.com/javase/1.4.2/docs/api/java/util/Properties.html

• C# properties are a value in the object
• Java properties are a way of saving the state to a file and reading it back

Another very nice Java/C# Comparison:  http://www.harding.edu/fmccown/java_csharp_comparison.html

• This one would be best to read first

Java random number generation:

• generating a number in a range:
• http://stackoverflow.com/questions/363681/java-generating-random-number-in-a-range

In doing Repast Simphony development, the RandomHelper class should be used:

• Don't be confused by some of the descriptions of how to do random number in earlier versions of Repast
• Use the RandomHelper
• http://repast.sourceforge.net/docs/reference/SIM/Random%20Numbers.html
• http://repast.sourceforge.net/docs/api/repastjava/repast/simphony/random/RandomHelper.html#RandomHelper()
• RandomHelper has only static methods.
• encapsulates the colt library's random number generation
• Very complicated
• used a uniform distribution by default
• can use
• Beta
• Binomial
• ChiSquare
• etc
• Wraps "Colt":  http://acs.lbl.gov/software/colt/

A very nice example of a Java singleton implementation:  http://www.javaworld.com/javaworld/jw-04-2003/jw-0425-designpatterns.html

Default parameters in Java:

• http://stackoverflow.com/questions/965690/java-optional-parameters
• Doesn't really exist in Java
• http://stackoverflow.com/questions/997482/does-java-support-default-parameter-values
• can be done but is a bit ugly

Calling a constructor within a constructor in Java:  http://stackoverflow.com/questions/285177/how-do-i-call-one-constructor-from-another-in-java

• this(); //without a parameter

Java coding style:

• http://geosoft.no/development/javastyle.html#Naming Conventions
• methods begin in lower case

Declaring generic arrays:

• http://forums.techarena.in/software-development/1117589.htm
• HashMap <?,?> [] x = new HashMap <?,?>[3];
• this work but I could access 'x'
• Best to avoid and wrap in a list instead
• List<HashMap<Class, Class> x = new ArrayList<HashMap<Class1, Class2>(3);
• the above code may not be correct, but it has the idea

C# ArgumentException can be changed to a Java IllegalArgumentException:  https://forums.oracle.com/forums/thread.jspa?threadID=472866

Comparing Java and C# Generics:  http://www.jprl.com/Blog/archive/development/2007/Aug-31.html

• performance advantages in C#

For each Loop in Java:

• http://download.oracle.com/javase/1,5.0/docs/guide/language/foreach.html
• for (List item : arrayList) { }

Generics and array construction in Java:

• http://stackoverflow.com/questions/217065/cannot-create-an-array-of-linkedlists-in-java
• is broken

Comparison between Java HashMap and .NET Hastable:  http://www.microsoft.com/mspress/books/sampchap/6173.aspx#116

Sorting a collection in Java: http://stackoverflow.com/questions/740299/how-do-i-sort-a-set-in-java

• List myList = new ArrayList (collection);
• Collections.sort (mylist);