10 Useful, Yet Paranoid, Java Programmer Techniques

Defensive java programming is a great way to prepare for the inevitable to go wrong -- but it can be just as paranoid as it is useful.

After coding for a while (eek, almost 20 years or so in my case, time flies when you’re having fun), one starts to embrace those habits. Because, you know…

Anything that Can Possibly Go Wrong, Does.

This is why people embrace “defensive programming”, i.e. paranoid habits that sometimes make total sense, and sometimes are rather obscure and/or clever and perhaps a bit eerie when you think of the person who wrote it. Here’s my personal list of top 10 useful, yet paranoid Java programming techniques. Let’s go:

1. Put the String Literal First

It’s just never a bad idea to prevent the occasional NullPointerException by putting the String literal on the left side of an equals() comparison as such:

// Bad

if (variable.equals("literal")) { ... }

// Good

if ("literal".equals(variable)) { ... }

This is a no-brainer. Nothing is lost from rephrasing the expression from the less good version to the better one. If only we had true Options though, right? Different discussion…

2. Don’t Trust the Early JDK APIs

In the early days of Java, programming must’ve been a big pain. The APIs were still very immature and you might’ve walked across a piece of code like this:

String[] files = file.list();

// Watch out

if (files != null) {

    for (int i = 0; i < files.length; i++) {

        ...

    }

}

Looking paranoid? Perhaps, but read the Javadoc:

If this abstract pathname does not denote a directory, then this method returns null. Otherwise an array of strings is returned, one for each file or directory in the directory.

Yeah right. Better add another check, though, just to be sure:

if (file.isDirectory()) {

    String[] files = file.list();

    // Watch out

    if (files != null) {

        for (int i = 0; i < files.length; i++) {

            ...

        }

    }

}

Bummer! Violation of rule #5 and #6 of our 10 Subtle Best Practices when Coding Java list. So be prepared and add that null check!

3. Don’t Trust That “-1″

This is paranoid, I know. The Javadoc of String.indexOf() clearly states that…

the index of the first occurrence of the character in the character sequence represented by this object [is returned], or -1 if the character does not occur.

So, -1 can be taken for granted, right? I say nay. Consider this:

// Bad

if (string.indexOf(character) != -1) { ... }

// Good

if (string.indexOf(character) >= 0) { ... }

Who knows. Perhaps they’ll need ANOTHER encoding at some point in time to say, the otherStringwould have been contained if checked case-insensitively… Perhaps a good case for returning -2? Who knows.

After all, we’ve had billions of discussions about the billion dollar mistake, which is NULL. Why shouldn’t we start discussions about -1, which is – in a way – an alternative null for primitive typeint?

4. Avoid the Accidental Assignment

Yep. It happens to the best (although, not to me. See #7).

(Assume this is JavaScript, but let’s be paranoid about the language as well)

// Ooops

if (variable = 5) { ... }

// Better (because causes an error)

if (5 = variable) { ... }

// Intent (remember. Paranoid JavaScript: ===)

if (5 === variable) { ... }

Again. If you have a literal in your expression, put it to the left side. You can’t accidentally go wrong here, when you meant to add another = sign.

5. Check for Null AND Length

Whenever you have a collection, array, etc., make sure it’s present AND not empty.

// Bad

if (array.length > 0) { ... }

// Good

if (array != null && array.length > 0) { ... }

You never know where those arrays come from. Perhaps from early JDK API?

6. All Methods Are Final

You can tell me all you want about your open/closed principles, that’s all bollocks. I don’t trust you (to correctly extend my classes) and I don’t trust myself (to not accidentally extend my classes). Which is why everything that is not explicitly intended for subtyping (i.e. only interfaces) is strictly final. See also item #9 of our 10 Subtle Best Practices when Coding Java list.

// Bad

public void boom() { ... }

// Good. Don't touch.

public final void dontTouch() { ... }

Yes. It’s final. If that doesn’t work for you, patch it, or instrument it, or rewrite the byte code. Or send a feature request. I’m sure that your intent of overriding the above isn’t a good idea anyway.

7. All Variables and Parameters Are Final

As I said. I don’t trust myself (to not accidentally overwrite my values). Having said so, I don’t trust myself at all. Because…

… which is why all variables and parameters are made final, too.

// Bad

void input(String importantMessage) {

    String answer = "...";

    answer = importantMessage = "LOL accident";

}

// Good

final void input(final String importantMessage) {

    final String answer = "...";

}

OK, I admit. This one, I don’t apply very often, really, although I should. I wish Java got it right like Scala, where people just type val all over the place, without even thinking about mutability – except when they need it explicitly (rarely!), via var.

8. Don’t Trust Generics When Overloading

Yes. It can happen. You believe you wrote that super nice API which totally rocks and is totally intuitive, and along comes some user who just raw-casts everything up to Object until the darn compiler stops bitching, and suddently they’ll link the wrong method, thinking it’s your fault (it always is).

Consider this:

// Bad

<T> void bad(T value) {

    bad(Collections.singletonList(value));

}

<T> void bad(List<T> values) {

    ...

}

// Good

final <T> void good(final T value) {

    if (value instanceof List)

        good((List<?>) value);

    else

        good(Collections.singletonList(value));

}

final <T> void good(final List<T> values) {

    ...

}

Because, you know… Your users, they’re like

// This library sucks

@SuppressWarnings("all")

Object t = (Object) (List) Arrays.asList("abc");

bad(t);

Trust me. I’ve seen everything. Including things like

It’s good to be paranoid.

9. Always Throw on Switch Default

Switch… One of those funny statements where I don’t know whether to petrify with awe or to just cry. Anyway, we’re stuck with switch, so we may as well get it right when we have to. I.e.

// Bad

switch (value) {

    case 1: foo(); break;

    case 2: bar(); break;

}

// Good

switch (value) {

    case 1: foo(); break;

    case 2: bar(); break;

    default:

        throw new ThreadDeath("That'll teach them");

}

Because that moment where value == 3 is introduced into the software, it’ll come for sure! And don’t say enum, because it’ll happen to enums as well!

10. Switch With Curly Braces

In fact, switch is the most wicked statement anyone has every allowed to get into a language while they were either drunk or lost a bet. Consider the following example:

// Bad, doesn't compile

switch (value) {

    case 1: int j = 1; break;

    case 2: int j = 2; break;

}

// Good

switch (value) {

    case 1: {

        final int j = 1;

        break;

    }

    case 2: {

        final int j = 2;

        break;

    }

    // Remember:

    default: 

        throw new ThreadDeath("That'll teach them");

}

Within the switch statement, there is only one scope defined among all the case statements. In fact, these case statements aren’t even really statements, they’re like labels and the switch is a goto call. In fact, you could even compare case statements with the astonishing FORTRAN 77 ENTRY statement, a device whose mystery is only exceeded by its power.

This means that the variable final int j is defined for all the different cases, regardless if we issue abreak or not. Not very intuitive. Which is why it’s always a good idea to create a new, nested scope percase statement via a simple block. (but don’t forget the break within the block!)

Conclusion

Paranoid programming may seem weird at times, as code often turns out to be a bit more verbose than really needed. You might think, “oh this is never gonna happen”, but as I said. After 20 years or so programming, you just don’t want to fix those stupid little unnecessary bugs anymore that exist only because the language is so old and flawed. Because you know…

Re-print from:  Lukas Eder 

Fast data processing with spark - review

Hi,
I've got that book "Fast data processing with spark" and yesterday I spend on reviewing it..
I will not go into deep details, just quick one: it was quite disappointing book:

• If you interested in one language (aka scala) then 1/3 of book is useless, as author is providing every example in 3 languages: scala/java/python.
• Together there are ... 2 examples, so not much to share/learn.
• Second example uses library that you cannot find anymore :-(, I mean - maybe if you spent more time to dig particular problem on geolocation - but do not use that book as geolocation solution. For general publicity not worth.
• Explanations what's going on on examples are really light - and this is me being polite. 

Book: Not recommended.

If you want to check "working solution" updated to 2015 code base with existing libraries, check my project on github: 

https://github.com/yarenty/spark_data_processing

LWJGL3 - use GPU [OpenCL] for multithreaded calculations

Lastly I spent some time investigating usage of GPU in computations, particularly nvidia CUDA. But during research I spent some time looking for other options, like OpenCL. So that brings me to this Lightweight Java Game Library.

Short intro:

LWJGL is a Java library that enables cross-platform access to popular native APIs useful in the development of graphics (OpenGL), audio (OpenAL) and parallel computing (OpenCL) applications. This access is direct and high-performance, yet also wrapped in a type-safe and user-friendly layer, appropriate for the Java ecosystem. LWJGL is an enabling technology and provides low-level access. It is not a framework and does not provide higher-level utilities than what the native libraries expose. As such, novice programmers are encouraged to try one of the frameworks or game engines that make use of LWJGL, before working directly with the library.   

And after quick look - you can get the same amount of access to all part of GPU as you can on JCUDA ( using CUDA of course ;-) ).

Here is simple OpenCL example  updated to use LWJGL3:

package com.yarenty.lwjgl3;

import org.lwjgl.opencl.CLUtil;
import org.lwjgl.BufferUtils;
import org.lwjgl.PointerBuffer;

import java.nio.FloatBuffer;
import java.nio.IntBuffer;
import java.util.List;

import org.lwjgl.opencl.CL;
import org.lwjgl.opencl.CLCreateContextCallback;
import org.lwjgl.opencl.CLDevice;
import org.lwjgl.opencl.CLPlatform;

import static org.lwjgl.opencl.CL10.*;
import static org.lwjgl.opencl.CLUtil.checkCLError;
import static org.lwjgl.system.MemoryUtil.NULL;
import static org.lwjgl.system.MemoryUtil.memDecodeUTF8;
 
public class OpenCLSum {
    // The OpenCL kernel
    static final String source =
        "kernel void sum(global const float *a, global const float *b, global float *answer) { "
        + "  unsigned int xid = get_global_id(0); "
        + "  answer[xid] = a[xid] + b[xid];"
        + "}";
 
    // Data buffers to store the input and result data in
    static final FloatBuffer a = toFloatBuffer(new float[]{1, 2, 3, 4, 5, 6, 7, 8, 9, 10});
    static final FloatBuffer b = toFloatBuffer(new float[]{9, 8, 7, 6, 5, 4, 3, 2, 1, 0});
    static final FloatBuffer answer = BufferUtils.createFloatBuffer(a.capacity());
 
    
 private static final CLCreateContextCallback CREATE_CONTEXT_CALLBACK = new CLCreateContextCallback() {
  @Override
  public void invoke(long errinfo, long private_info, long cb, long user_data) {
   System.err.println("[LWJGL] cl_create_context_callback");
   System.err.println("\tInfo: " + memDecodeUTF8(errinfo));
  }
 };
    
    public static void main(String[] args) throws Exception {
     
     System.setProperty("org.lwjgl.opencl.explicitInit","true");
     
     
        // Initialize OpenCL and create a context and command queue
        CL.create();
        System.out.println("CL created");
        
        CLPlatform platform = CLPlatform.getPlatforms().get(0);
        System.out.println("Platform created");

        PointerBuffer ctxProps = BufferUtils.createPointerBuffer(3);
  ctxProps.put(CL_CONTEXT_PLATFORM).put(platform).put(0).flip();
  System.out.println("CTX created");
  
  
        IntBuffer errcode_ret = BufferUtils.createIntBuffer(1);
  System.out.println("ERRCODE created");

        
        List devices = platform.getDevices(CL_DEVICE_TYPE_GPU);
       // long context = clCreateContext(platform, devices, null, null, null);
  long context = clCreateContext(ctxProps, devices.get(0).getPointer(), CREATE_CONTEXT_CALLBACK, NULL, errcode_ret);
  System.out.println("CONTEXT created");

  
  checkCLError(errcode_ret);
        //CLCommandQueue queue = clCreateCommandQueue(context, devices.get(0), CL_QUEUE_PROFILING_ENABLE, null);
        long queue = clCreateCommandQueue(context, devices.get(0).getPointer(), CL_QUEUE_PROFILING_ENABLE, errcode_ret);
  System.out.println("Command Q created");

        // Allocate memory for our two input buffers and our result buffer
        long aMem = clCreateBuffer(context, CL_MEM_READ_ONLY | CL_MEM_COPY_HOST_PTR, a, null);
        //long buffer = clCreateBuffer(context, CL_MEM_READ_ONLY, 128, errcode_ret);
  System.out.println("A Buffer created");
        clEnqueueWriteBuffer(queue, aMem, 1, 0, a, null, null);
        long bMem = clCreateBuffer(context, CL_MEM_READ_ONLY | CL_MEM_COPY_HOST_PTR, b, null);
  System.out.println("B Buffer created");
        clEnqueueWriteBuffer(queue, bMem, 1, 0, b, null, null);
        long answerMem = clCreateBuffer(context, CL_MEM_WRITE_ONLY | CL_MEM_COPY_HOST_PTR, answer, null);
  System.out.println("OUTPUT Buffer created");
        clFinish(queue);
 
        // Create our program and kernel
        long program = clCreateProgramWithSource(context, source, null);
  System.out.println("PROGRAM created");

     //public static int clBuildProgram(long program, long device, CharSequence options, CLProgramCallback pfn_notify, long user_data) {

      
        CLUtil.checkCLError(clBuildProgram(program, devices.get(0).getPointer(), "", null, 0L));
        // sum has to match a kernel method name in the OpenCL source
        long kernel = clCreateKernel(program, "sum", null);
  System.out.println("KERNEL created");

        // Execution our kernel
        PointerBuffer kernel1DGlobalWorkSize = BufferUtils.createPointerBuffer(1);
        System.out.println("KERNEL work size created");
        kernel1DGlobalWorkSize.put(0, a.capacity());
        System.out.println("KERNEL work size copied");
        
        clSetKernelArg1p(kernel, 0, aMem);
        clSetKernelArg1p(kernel, 1, bMem);
        clSetKernelArg1p(kernel, 2, answerMem);
        
  System.out.println("Args send to kernel");

        clEnqueueNDRangeKernel(queue, kernel, 1, null, kernel1DGlobalWorkSize, null, null, null);
        System.out.println("KERNEL queued created");
        
        
        // Read the results memory back into our result buffer
        clEnqueueReadBuffer(queue, answerMem, 1, 0, answer, null, null);
        System.out.println("and output ... created");
        
        clFinish(queue);
        // Print the result memory
        print(a);
        System.out.println("+");
        print(b);
        System.out.println("=");
        print(answer);
 
        // Clean up OpenCL resources
        clReleaseKernel(kernel);
        clReleaseProgram(program);
        clReleaseMemObject(aMem);
        clReleaseMemObject(bMem);
        clReleaseMemObject(answerMem);
        clReleaseCommandQueue(queue);
        clReleaseContext(context);
        CL.destroy();
    }
 
 
    /** Utility method to convert float array to float buffer
     * @param floats - the float array to convert
     * @return a float buffer containing the input float array
     */
    static FloatBuffer toFloatBuffer(float[] floats) {
        FloatBuffer buf = BufferUtils.createFloatBuffer(floats.length).put(floats);
        buf.rewind();
        return buf;
    }
 
 
    /** Utility method to print a float buffer
     * @param buffer - the float buffer to print to System.out
     */
    static void print(FloatBuffer buffer) {
        for (int i = 0; i < buffer.capacity(); i++) {
            System.out.print(buffer.get(i)+" ");
        }
        System.out.println("");
    }
 
}

and you can find full scala project here: https://github.com/yarenty/scala_lwjgl3

Defaults - base start configurations for new projects.

Every single time I'm starting new projects there is time which I spent on "organising" stuff:
- for maven create initial pom.xml
- for scala  - build.sbt
- or define gitignore for different type of projects.
I know that there is some handy tools like gitignore generators, etc...
Tell you truth every single time I finish with going through all my previous projects and trying to find something close to the one that I'm doing at the moment. Then look into libraries to find if there are some new ones worth upgrading ...  Yes, i know it could be fun, but ...

Finally I decided to do some life hack and have my BASE DEFAULTS -  I created this project:  https://github.com/yarenty/DEFAULTS

And hope I will keep them updated.


PS: Apart standard one I'm keeping stuff like "must install in new eclipse"

Findbugs:
http://findbugs.cs.umd.edu/eclipse
PMD:
http://sourceforge.net/projects/pmd/files/pmd-eclipse/update-site/
Checkstyle:
http://eclipse-cs.sourceforge.net/update/
or new marketplace version:
http://eclipse-cs.sourceforge.net/

Quick PX to EM conversion table for responsive web layouts

This is simple table to remember or to do automatic replace when you'll go from old non-responsive design to responsive one.

Just one tip: when you'll replace automatically start from the biggest number ;-)

px	em
1 px	0.0625
2 px	0.125
3 px	0.1875
4 px	0.25
5 px	0.3125
6 px	0.375
7 px	0.4375
8 px	0.5
9 px	0.5625
10 px	0.625
11 px	0.6875
12 px	0.75
13 px	0.8125
14 px	0.875
15 px	0.9375
16 px	1.0
17 px	1.0625
18 px	1.125
19 px	1.1875
20 px	1.25
21 px	1.3125
22 px	1.375
23 px	1.4375
24 px	1.5
25 px	1.5625
26 px	1.625
27 px	1.6875
28 px	1.75
29 px	1.8125
30 px	1.875
31 px	1.9375
32 px	2.0
33 px	2.0625
34 px	2.125
35 px	2.1875
36 px	2.25
37 px	2.3125
38 px	2.375
39 px	2.4375
40 px	2.5
50 px	3.125
80 px	5.0
100 px	6.25
120 px	7.5
640 px	40.0
920 px	57.5
960 px	60.0

Ubuntu 14.04 + apple time capsule

Finally got access to time capsule. 

1) install libraries:

sudo apt-get install libgcrypt11 libgcrypt11-dev libgmp3-dev readline-common libreadline6 libreadline6-dev libfuse2 libfuse-dev libncurses5-dev

2) download afpfs (link here)
3) unarchive afpfs ( tar -xzvf )
4) navigate to afpfs (cd afpfs*)
5) you will have to patch the afpfs because it has a bug in ubuntu 12.04 /13.04 and still in 14.04:

wget -O offset.diff https://bugzilla.redhat.com/attachment.cgi?id=397155 && patch -p1 < offset.diff

wget -O afpfs-ng-0.8.1-pointer.patchhttps://bugzilla.redhat.com/attachment.cgi?id=505576 && patch -p1 < afpfs-ng-0.8.1-pointer.patch

6) supposing you are in afpfs folder you archived:

sudo configure --prefix=/usr

sudo make install

7) now you should be able to connect to your timecapsule using this:

mkdir ~/capsule

8) Command for MOUNT: 

mount_afp afp://user:password@server_host_or_ip/Data ~/capsule

9)Command for UNMOUNT:

afp_client unmount ~/capsule

You should see a “capsule” folder in your home folder.
In my case Time Capsule stands on 10.0.1.1

Thanks to alex!

Scala1: Scala is craaazy

I finished scala course provided by Martin Odersky.  And just want to test them in some real case scenario. I had quite easy task: there is csv file, with headers, which need to be imported to database. Normal times when I used java I prepared myself for few days of coding. Typical steps are:

1. csv: find/list java csv processing libraries
2. csv: read / investigate few of them
3. csv: start playing, when one do not work as expected - check another one
4. db: fight with proper driver
5. db: find how to connect
6. db: prepare statements/sqls/ etc..
7. finally connect csv+db into one solution, and make it work smoothly

And after few days I would have working solution with probably few hundred lines of code...(not to mention tests/documentation).

In scala (and I am novice):
  1. created my single object "importer.scala"
  2. whole csv solution finished with adding to my build.sbt file single line:

libraryDependencies += "com.github.tototoshi" %% "scala-csv" % "1.1.2"

as my csv file using ";" as separator I put :

  implicit object MyFormat extends DefaultCSVFormat {
    override val delimiter: Char = ';'  }

then to main function I added 2 lines of code:

    val reader = CSVReader.open("myfile.csv")(MyFormat)
    val full = reader.allWithHeaders

and ... that is it - whole csv solution done in less than 15 mins! (and yes in java I also used sbt like solution - i.e.:maven)

  3. DB part: 

Connection - again to build.sbt, added just one line (I'm using MySQL):

libraryDependencies += "mysql" % "mysql-connector-java" % "5.1.34"

..  and again to main function just added database connection

 val dbc = "jdbc:mysql://localhost:3306/mydb?user=me&password=123"
    Class.forName("com.mysql.jdbc.Driver")   

val conn = DriverManager.getConnection(dbc)

and coding ... lets go ;-) :

    try {
      full.foreach(fields => processFields(fields, conn))
    } finally {
      conn.close
    }

I know that I could do everything inside "full.foreach" but I had some old java habits to create methods for different actions... so I just added processFields function.

  def processFields(in: Map[String, String], conn: java.sql.Connection) {
    val l: MutableList[String] = new MutableList[String]()
    fieldTypes.foreach(f =>
      l += (in.get(f).get).replace("\"", "\\\""))
    val sql = "INSERT INTO temp_products (" + myTypes.mkString(",") +      ") VALUES ( " + "\"" + l.mkString("\",\"") + "\")"
    val prep = conn.prepareStatement(sql)
    prep.executeUpdate
  } 

As you see I had issue with ["] sign - which sometimes appeared inside csv fields.
This is plain/native sql - and whole solution takes me less than 2 hours.

Must say: I was little disappointed with ... so little effort to make things work.
And all I had is 60 lines of code - I really don't see reason to write comments/documentation as this is so obvious (if you know scala) that basically anything more will be overhead.

In next post I will show you about slick - proper DB/ORM mapping in scala and .. how easy is to do reverse engineering - generate objects from DB tables and do some crazy sqls without sql ;-)

Websites - Mobile Development

Few tools and tricks for mobile website development - very RAW info.

Simulators

• Android AVD Manager
• Blackberry Ripple Emulator
• Opera Mobile
• Windows Phone Emulator

IDE

• Aptana

Validation tools

http://validator.w3.org

• W3C HTML5 validator
• W3C CSS Validation Service

Debugging tools

Most browsers (F12 ;-) )  + Chrome, Firefox and OperaMobile support remote debugging
To stay sane: get your site working with a desktop browser and emulator then test on real devices.

Responsive Web Design

• Fluid layout width - layouts that resize to fit in the available screen space
• Media queries - load different CSS depend on screen size
• flexible images and media - to suit screen size and bandwidth
• typesetting: use em or % instead px

Box Problem

.borderBox *
{
  -moz-box-sizing:border-box;
  -webkit-box-sizing:border-box;
  box-sizing:border-box;
}

RWD Formula

result = target/context
25px (target) / 16px (context) = 150% (result) => 1.5 em 

CSS reset

Reset style sheets between different browsers (for consistency):

• Eric Meyer's Reset
• HTML5 Doctor CSS Reset
• Yahoo! Reset CSS
• Normalize.css

http://cssreset.com

Media queries

@media screen and (max-width: 479px) {
 # header-logo {
   width:75%
   margin: 0 auto 0 } }
@media screen and (max-width: 737px) {
 # header-logo {
   width:100%
   margin: 0 0 0 0 } }

Support good across browsers, except IE ( from IE9+) - use respond.js to emulate:

https://github.com/scottjehl/Respond

Screen widths

<meta name="viewport" content="width=device-width, user-scalable=yes, initial-scale=1.0" />
+ css:
@viewport {
  width: device-width;
  zoom: 1.0;
  user-zoom: zoom;
}

ICON

http://realfavicongenerator.net/

Responsive Navigation Menus

http://speckyboy.com/2012/08/29/10-responsive-navigation-solutions-and-tutorials/

Images

Prevent media from overflowing it's container:

img,embed,object, video {
  max.width: 100%
}

 for IE:

 <!-- [if IE<=8]>
 <link rel="stylesheet" href="ie-style.css"/>
<![endif]-->

img.rwd { width:100%; height:auto; }

Image Adaption

Server-Side

• WURFL
• Adaptive images ( http://adaptive-images.com)

Client-Side

• HiSRC jQuery plugin https://github.com/teleject/hisrc
• Picturefill https://github.com/scottjehl/picturefill

HTML5 <picture> element

Supported in older browsers by Picturefill script

<picture>
 <source media="(min-width: 45em)" srcset="large.jpg">
 <source media="(min-width: 18em)" srcset="med.jpg, med-hd.jpg 2x">
 <source srcset="small.jpg">
 <img src="small.jpg" alt="some text">
 <p>some text</p>
</picture>

JQuery Mobile - jQM

Gallery: http://www.jqmgallery.com

data-role:

• page
• header
• content
• footer

ThemeRoller: http://jquerymobile.com/themeroller

Modernizr

Open-source JavaScript feature-detection library http://modernizr.com

if (Modernizr.touch) { // code for toechscreen
} else { // no touchscreen
}

Modernizr.localStorage (sessionStorage)

Modernizr.geolocation

            data.setCurrentLocation = function () {
     if (Modernizr.geolocation) {
             navigator.geolocation.getCurrentPosition(data.geoSuccess, data.geoError);
            } else {
            data.geoError('not supported');
            }
            };
         
            data.geoSuccess =  function (position) {
             var s = document.querySelector('#status');
           
             if (s.className == 'success') { //Firefox fix
                return;
             }
           
              s.className = 'success';
            
              data.currentLatLng = new google.maps.LatLng(position.coords.latitude, position.coords.longitude);
           
              var myOptions = {
               zoom: 15,
               center: data.currentLatLng,
               mapTypeControl: true,
               navigationControlOptions: {style: google.maps.NavigationControlStyle.SMALL},
               mapTypeId: google.maps.MapTypeId.ROADMAP
             };
           
             data.currentLocationMap = new google.maps.Map(document.getElementById("map_canvas"), myOptions);
             var currentPositionMarker = new google.maps.Marker({
                   map: data.currentLocationMap,
                   position: data.currentLatLng
               });
            };

Links

• HTML 5 Documentation
• CSS3 Documentation
• JavaScript Documentation
• JQuery API Reference
• JQuery Mobile API Reference
• PhoneGap Documentation

• Blackberry Ripple Emulator
• Blackberry Kitchen Sink App
• Ripple Emulator Usage Article
• jQuery Mobile Theme Roller

CUDA - Java integration

The last time I worked with CUDA was 3 years ago, and the only option to integrate was by using a bridge through C -> JNI (or JNI-like). Now I did some quick research on possibilities that are there and ... there are lots of them.

There are existing 3 types of integration:

1. (Byte)code translation and OpenCL code generation
2. Language extensions
3. Java OpenCL/CUDA binding libraries

(Byte)code translation and OpenCL code generation

• http://code.google.com/p/aparapi/ : An open-source library that is created and actively maintained by AMD. In a special "Kernel" class, one can override a specific method that should be executed in parallel. The byte code of this method is loaded at runtime using its own bytecode reader. The code is translated into OpenCL code, which is then compiled using the OpenCL compiler. The result can then be executed on the OpenCL device, which may be a GPU or a CPU. If the compilation into OpenCL is not possible (or no OpenCL is available), the code will still be executed in parallel, using a Thread Pool.
• https://github.com/pcpratts/rootbeer1 : An open-source library for converting parts of Java into CUDA programs. It offers dedicated interfaces that may be implemented to indicate that a certain class should be executed on the GPU. In contrast to Aparapi, it tries to automatically serialize the "relevant" data (that is, the complete relevant part of the object graph!) into a representation that is suitable for the GPU.
• http://code.google.com/p/java-gpu/ : A library for translating annotated Java code (with some limitations) into CUDA code, which is then compiled into a library that executes the code on the GPU. The Library was developed in the context of a PhD thesis, which contains profound background information about the translation process.
• http://code.google.com/p/scalacl/ : Scala bindings for OpenCL. Allows special Scala collections to be processed in parallel with OpenCL. The functions that are called on the elements of the collections can be usual Scala functions (with some limitations) which are then translated into OpenCL kernels.

Language extensions

• http://www.ateji.com/px/index.html : A language extension for Java that allows parallel constructs (e.g. parallel for loops, OpenMP style) which are then executed on the GPU with OpenCL. Unfortunately, this very promising project is no longer maintained.
• http://www.habanero.rice.edu/Publications.html (JCUDA) : A library that can translate special Java Code (called JCUDA code) into Java- and CUDA-C code, which can then be compiled and executed on the GPU. However, the library does not seem to be publicly available.
• https://www2.informatik.uni-erlangen.de/EN/research/JavaOpenMP/index.html : Java language extension for for OpenMP constructs, with a CUDA backend

Java OpenCL/CUDA binding libraries

• http://jcuda.org/ : Java bindings for CUDA: Low-level bindings that are a 1:1 mapping of the original CUDA API
• http://jocl.org/ : Java bindings for OpenCL: Low-level bindings that are a 1:1 mapping of the original OpenCL API
• http://code.google.com/p/javacl/ : Java bindings for OpenCL: An object-oriented OpenCL library, based on auto-generated low-level bindings
• http://jogamp.org/jocl/www/ : Java bindings for OpenCL: An object-oriented OpenCL library, based on auto-generated low-level bindings
• http://www.lwjgl.org/ : Java bindings for OpenCL: Auto-generated low-level bindings and object-oriented convenience classes

How to fix MacBook Pro touchpad on Ubuntu 14.04

I spend few long hours to try to fix default crappy touchpad behavior, before finally I got to this.
And by "crappy" I mean: not working gestures, buttons clicked on random, cannot properly select text, etc... basic test: you simply cannot play solitaire ;-).

Finally I found mtrack! 

3 easy steps:
1) install

sudo apt-get install xserver-xorg-input-mtrack

2) at the bottom of configuration add those settings (instead vi you could use nano/gedit):

sudo vi /usr/share/X11/xorg.conf.d/50-synaptics.conf

my settings are:

Section "InputClass"
        MatchIsTouchpad "on"
        Identifier      "Touchpads"
        Driver          "mtrack"
        Option          "Sensitivity" "0.95"
        Option          "FingerHigh" "12"
        Option          "FingerLow" "1"
        Option          "IgnoreThumb" "true"
        Option          "IgnorePalm" "true"
        Option          "TapButton1" "0"
        Option          "TapButton2" "0"
        Option          "TapButton3" "0"
        Option          "TapButton4" "0"
        Option          "ClickFinger1" "1"
        Option          "ClickFinger2" "3"
        Option          "ClickFinger3" "3"
        Option          "ButtonMoveEmulate" "false"
        Option          "ButtonIntegrated" "true"
        Option          "ClickTime" "25"
        Option          "BottomEdge" "25"
        Option          "SwipeLeftButton" "8"
        Option          "SwipeRightButton" "9"
        Option          "SwipeUpButton" "0"
        Option          "SwipeDownButton" "0"
        Option          "ScrollDistance" "75"
        Option          "ScrollUpButton" "5"
        Option          "ScrollDownButton" "4"
EndSection

note ScrollUpButton/ScrollDownButton - changed to default apple like behavior ("natural");

3) restart and enjoy:

sudo restart lightdm