Java Review: Tuesday, October 12, 2011

Java Run-time Exceptions

http://download.oracle.com/javase/1.4.2/docs/api/java/lang/IllegalStateException.html

• Class IllegalStateException
• example
• throw new IllegalStateException();
• use to catch programming development errors.
• exception should never occur unless there is a programming error.

http://download.oracle.com/javase/tutorial/essential/exceptions/throwing.html

• tutorial

http://download.oracle.com/javase/1.4.2/docs/api/java/lang/RuntimeException.html

• Class RuntimeException
• not checked
• not extra code
• danger of being a 'lazy programmer'

http://download.oracle.com/javase/tutorial/essential/exceptions/runtime.html

• can use to side step catch and specify requirements
• Runtime exceptions represent problems that are the result of programming problems
• If the client can reasonable be expected to recover from an exception, make it a checked exception

Garbage Collection in Java VMs

http://terracotta.org/products/bigmemory?asrc=eliminate-java-gc-tuning-2-gc-sno&gclid=CKzY28G346sCFcPt7Qod4kU9Rg

• Big memory
• works with
• JVMs
• HotSpot
• IBM JDK
• JRockit
• what about Dalvik?
• off-heap store
• not subject to Java GC
• Terracotta's tiered cache
• Enterprise Ehcache
• store up to a terabyte in the off-heap

http://www.koushikdutta.com/2009/01/dalvik-vs-mono.html

• Dalvik vs Mono

http://stackoverflow.com/questions/3078301/dalvik-memory-allocation-how-to-change-the-default-limits

• heap-limits set by OEM with Dalvik

http://pallergabor.uw.hu/androidblog/dalvik_opcodes.html

• Dalvik opcodes

http://mylifewithandroid.blogspot.com/2008/12/dalvik-opcodes.html

• DEX file format

http://mylifewithandroid.blogspot.com/2009/12/understanding-dalvik-bytecode-with.html

• Dalvik bytecode and Dedexer tool

http://en.wikipedia.org/wiki/Java_Virtual_Machine

• overview of Java VM

http://ryanolson.wordpress.com/2010/07/13/test-how-changing-the-max-amount-of-memory-per-vm-heap-can-effect-your-rom-cyanogen/

• Cyanogen allow Dalvik VM settings to be modified

http://blog.javia.org/android-allocation-free-code-avoids-the-gc-freeze/

• allocation-free code to avoid GC freeze

http://developer.android.com/guide/practices/design/performance.html

• Android, designing from performance

http://www.xinotes.org/notes/note/1449/

• heap size can be change in 'dx'
• example of changing

http://stackoverflow.com/questions/2298784/determine-when-the-android-gc-runs

• code to see the android GC run

http://stackoverflow.com/questions/1521317/is-it-possible-to-call-gc-in-android

• requesting GC
• System.gc();
• no guarantee it will run

Java Constants and Conditional Compile

http://www.javaworld.com/javaworld/javatips/jw-javatip5.html

• No textual preprocessor
• constants and conditional compilation
• use public static final boolean constant for  a regular if statement in regular code
• Have class using the constant interface implement the constant interface

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