Eclipse fails to start after a Mac OS X system crash

Are you seeing crashes on your Eclipse start up? Follow these instructions! Really handy tip by Sergio Bernardino. It indeed fixed my issue on my new Mac :)

- Make sure Eclipse is not running.
- On a Terminal window jump to the location of Eclipse workspace.

Do,

mv .metadata/.plugins/org.eclipse.core.resources/.projects .metadata/.plugins/org.eclipse.core.resources/old.projects

- Launch Eclipse (it should load now).
- Go to “Eclipse->Preferences->General->Startup and Shutdown”and select “Refresh workspace on startup”.
- Quit Eclipse (ignore any of the errors that might be displayed).
- Go back to the terminal window.


Do, 

mv .metadata/.plugins/org.eclipse.core.resources/old.projects .metadata/.plugins/org.eclipse.core.resources/.projects

Load Eclipse again.

After this, everything should be fine and the same issue won’t happen again.

Source

Android NDK - Configure Eclipse to invoke native C/C++ code and library in Android

Android NDK allows you to implement part of Android program in native code language such as C/C++.  It's often mistake for Android developers to jump into NDK and delegate heavy computational part into native libraries written in C/C++ for performance improvements. However, as stated in the NDK documentation,

Notably, using native code on Android generally does not result in a noticable performance improvement, but it always increases your app complexity. In general, you should only use the NDK if it is essential to your app—never because you simply prefer to program in C/C++  

Today, I am going to cover how I managed to configure my Eclipse environment to start developing with Android NDK. Before you proceed the rest of tutorial, think twice. Make sure you are doing this for code reuse and portability and not for computational performance benefits.

Prerequisite

This tutorial assumes you have installed Android SDK environment, Java JDK, and Android ADT plugin. If you haven't installed any of those things listed above, follow the tutorial posted by Android code monkey. Once you are done with that, create a new Android project in your Eclipse environment and follow the rest of the tutorial.

Android NDK Installation 

- Install Android NDK
- Unzip Android NDK  (i.e. C:\Android\android-ndk-r8 or /usr/local/android/android-ndk-r8)

Native Code Configuration (C/C++ code)

Install C/C++ Eclipse plugin
- Choose Help -> Install New Software… from the main menu.
- Choose http://download.eclipse.org/releases/galileo as the source site. If you have another Eclipse release than Galileo choose the appropriate url.



Create JNI folder in your eclipse project
- A folder named 'jni' (lowercase) must be created by you in the Eclipse project's root directory.
 

Create C/C++ JNI sources (example.c)
- Create your c files in jni directory you created above
- For the tutorial, I created example.c to illustrate the basics. I wrote a simple function called initEngine(int x) that doubles up the int x passed and returns the sum.
 

Header Information

- You must have #include and this is necessary for all the JNI configuration in your native code

Return Type

- JNIEXPORT int JNICALL
      - int - return type of your JNI call

Function Declaration 

- Functional declaration in between _ has meanings:
     - Java: We will use Java to invoke this native code
     - com_goeverywhere_jni: package representation of your Java JNI class. 

     - JNILoader: name of the Java class 

     - initEngine: method name within the Java class

Function parameters

- (JNIEnv * env, jobject obj) - this is required for JNI invocation
- Parameters preceding above is the parameter for your function declaration
     - jint x: this is added for my JNI function parameter for initEngine(int x)

Create Android.mk

Android.mk is a makefile needed to compile your native sources between Android NDK and your native code. Information writing on Android.mk file can be found in 'docs' folder inside the Android NDK folder. The most relevant document is the 'ANDROID-MK.TXT'



- LOCAL_PATH - path of your module. $(call my-dir) refers to same directory as the 'Android.mk' file
- LOCAL_MODULE - module name. This name should not have any spaces in it as it will be made into the actual library's name ('libexample.so' for us).
- LOCAL_CFLAGS - compiler flags.
- LOCAL_SRC_FILES - source file name

Write Java JNI library in Java

Now, let's write some Java code!

- Notice that the prefix of function declaration of native c function written above (i.e. Java_com_goeverywhere_jni_JNILoader_initEngine) must match with the Java package represenatation

- System.loadLibrary(module) must be invoked to load the native module via JNI and this must match what you defined in Android.mk:LOCAL_MODULE

- The functional declaration in java side must match with native declarations above with special keyboard native

Configure Eclipse Builder 

There are multiple ways you can compile what you have implemented above. You can install cygwin and install packages associated with it to compile with GCC libraries that comes with it. However, Android NDK already ships with precompiled version of make files and other necessary bundles.

I didn't want to deal with going into Cygwin or cmd prompt everytime I compile my code. Therefore, what I ended up doing is simply configuring an Eclipse Builder that automatically builds using ndk-build.cmd from Android NDK.

Right click on your project -> Properties -> Builders

Create a new Eclipse Project builder 

- Location: refer to ndk-build.cmd from your Android NDK installation directory
- Working Directory: reference to your Android project in your Eclipse

Eclipse Project builder -> Refresh tab

- libs directory is where your Android project looks for compiled resources (jars, libs) by default
- Click "specify resources" and configure location of libs directory
- Once you configure this and refresh your project, your builder will execute and compile all the source codes for you!

Eclipse Project builder -> Build options

- Navigate to "Build Options" tab
- Click "specify resources" and configure your location of jni directory

You are done!

- Your console will show that you have successfully compiled your sources. Depending on your CPU architecture, your compiled library will be compiled into the appropriate folder in your libs (i.e. armeabi)

Designing UI elements with Android fragment and Android SDK Manager issues I ran into

Implementing your Android UI with fragment not only makes your application components more modular, this is an optimal design for multiple platform if you plan to target your application to be available in all Android platforms such as tablets, Google TV, and mobile. Android introduced fragment in API 3.0 but you don't necessary want to make your min API level to 11+ because then the devices with lower API won't be able to download your application in Google play store.

As seen from graph above, it seems very wise to design min API as low as Android 2.2 to grab the most of the market share. It turns out you can still use Android fragment feature from 3.0 API without increasing the min API level in your application by utilizing Android compatibility package. This requires you to download the support package using Android SDK manager. I also found out there's a sample project comes from your android-sdk\samples\android-xx\APIDemos but when I tried to import the project into the workspace, it gave me the following error:

You do not have the latest version of the SDK Tools installed: Please update.

So it looks like I need SDK Tools and compatibility package - no problem. I decided to simply download latest API levels/support/compatibility packages because who knows if I have to end up debugging particular version of the android. You will get a pop up from motodev and htcdev asking for developer credentials but no worries they are legit - you can create an account for free on their website. After creating developer account, I tried it again - While attempting doing so, I ran into more errors in Android SDK manager. Depending on what you have currently installed in the system, you will get an error:

File not found: ...\android-sdk\temp\google_apis-15_r02.zip (Access is denied)

[2012-04-24 00:01:20 - SDK Manager] Skipping 'Android SDK Tools, revision 19'; it depends on 'Android SDK Platform-tools, revision 11' which was not installed.

Error after error!! One thing to note about access is denied error is that it's not a precise error message. In my case, I simply didn't have anything in that folder. I then thought I might have been to ambitious to install everything at once. Therefore, I just decided to install Android SDK Platform-tools, revision 11 then but SDK manager is still not happy.

Failed to rename directory C:\android-sdk\tools to C:\android-sdk\temp...

The error might tell you to turn off anti-virus because you expose yourself to security risks, make sure you don't have command prompts or folders opened associated with android-sdk. I have no idea why Android SDK tools is not fully backward compatible but I figured out a workaround here eventually. To summarize the trick, I had to do the following:

INSTRUCTIONS:

1. make a copy of the tools directory and call this new directory tools2.

2. DO NOT USE 'SDK Setup.exe'.

3. Instead open up a cmd.exe window as administrator and run the following from this new tools2 directory (obviously the full path on your local machine will be different):

android-sdk-dir> tools2\android.bat update sdk

Basically, as noted before in this thread, 'SDK Setup.exe' invokes tools\android.bat, which makes it impossible for it to rename the tools directory thereafter. It's a bit goofy and should never have passed QA validation..

After you execute the command above, you will be prompted with Android SDK manager and you will be able to install anything you wish for in Android SDK manager. Sudos kudos!

Eclipse in Windows: Cannot run program (CreateProcess error=87), The parameter is incorrect

You will see this when you exceed the character limits on Windows machine in your Java classpath. The character limit for the Windows is the following:

- Windows XP: 8189 characters
- Windows 7: around 33k characters

You will have to somewhat shorten the classpath. There are potential work arounds to this problem.

1) Use the network drive to shorten the classpath

You can use the network drive to shorten the classpath. Instead of having C:\Program Files\Apache\Maven 3.0\....\\xxx.jar, you can shorten the entire path to (i.g. M:\xxx.jar). Make sure to update your Maven's settings.xml and configure your m2clipse settings accordingly.


2) Use -Djava.ext.dirs JVM parameter and exclude Maven dependencies from your run configuration

It's possible that you might still run into exceeding the class path issue even after setting up the network drive. If this is the case, follow the below steps to resolve the issue.

You can use maven's dependency plugin to export all the transitive dependency jars into the specific location. Look Maven dependency plugin. Configure the Maven dependency plug-in on your pom then execute "mvn dependency:copy-dependencies" to export the jars into the folder (i.e. libs).

Once you have exported all the jars, navigate your Eclipse's runtime configurations. Go to Arguents -> VM arguments and add the -Djava.ext.dirs=libs (if your jar folder is libs). Note that this VM argument is separated by ; so you can enter multiple folders.

Eclipse is running in a JRE, but a JDK is required

When installing m2eclipse plugin, you might get an error like this in a eclipse console

"Eclipse is running in a JRE, but a JDK is required"

Problem can be solved simply by editing eclipse.ini file from your eclipse installation directory.

The key is that the -vm entry must come before the -vmargs entry. Also, make sure to have a line break between

-vm

and the path.

So in the eclipse.ini file:

THIS WILL NOT WORK:
-vm C:\java\jdk\bin\javaw.exe

BUT THIS WILL:
-vm
C:\java\jdk\bin\javaw.exe

Google Web Toolkit (GWT) CRUD - SmartGWT

I found this extensive GWT widget developed and licensed under GNU. From the all the GWT frameworks I have seen, this is the best one so far. It has over 260 showcase features and it is open source!. One of the biggest strength of this framework is the support for data integration/binding. GWT is an amazing tool. However, it doesn't have much of built-in framework for form validation/binding. Writing the code for data binding/validation in GWT can consume a lot of time. SmartGWT has amazing API functions to deal these obstacles with just a couple lines of code!

Look at the show case below:
http://www.smartclient.com/smartgwt/showcase/#add_grid_form_category

Pay close attention to Grid-Form-Binding. Writing GWT CRUD screen with SmartGWT sounds like a piece of cake!

For more information:
- Google code: http://code.google.com/p/smartgwt/
- Showcase: http://www.smartclient.com/smartgwt/showcase/

Spring MVC Attachment Upload/Download Handler

I implemented an attachment upload/download handler using Spring MVC. Uploading was just a piece of cake because all I had to was wiring the multipart resolver into the configuration and have a bean injected to it. Spring documentation was all I needed.

However, downloading was more tricky. I have to get response's output stream, set mime type and write the byte arrays to it. I found out this great mime type list for 2007 office. Even after I set the mime types for the response, .docx was saying that the file was corrupt. Once I click "Yes" on the recovery, it comes back fine but I am not sure why it is getting corrupted as all the other attachments come back just perfect. If anyone has any insights on this issue, please let me know.

Office 2007 Mime Types
.docm, application/vnd.ms-word.document.macroEnabled.12
.docx, application/vnd.openxmlformats-officedocument.wordprocessingml.document
.dotm, application/vnd.ms-word.template.macroEnabled.12
.dotx, application/vnd.openxmlformats-officedocument.wordprocessingml.template
.potm, application/vnd.ms-powerpoint.template.macroEnabled.12
.potx, application/vnd.openxmlformats-officedocument.presentationml.template
.ppam, application/vnd.ms-powerpoint.addin.macroEnabled.12
.ppsm, application/vnd.ms-powerpoint.slideshow.macroEnabled.12
.ppsx, application/vnd.openxmlformats-officedocument.presentationml.slideshow
.pptm, application/vnd.ms-powerpoint.presentation.macroEnabled.12
.pptx, application/vnd.openxmlformats-officedocument.presentationml.presentation
.xlam, application/vnd.ms-excel.addin.macroEnabled.12
.xlsb, application/vnd.ms-excel.sheet.binary.macroEnabled.12
.xlsm, application/vnd.ms-excel.sheet.macroEnabled.12
.xlsx, application/vnd.openxmlformats-officedocument.spreadsheetml.sheet
.xltm, application/vnd.ms-excel.template.macroEnabled.12
.xltx, application/vnd.openxmlformats-officedocument.spreadsheetml.template

DisplayTag feature to expose row numbers

I was working on Spring MVC and DisplayTag to structure the table. I had a list of objects and needed to refer the index of an item because I had to use <spring:bind>

I discovered a cool DisplayTag feature that exposes the row number of an item. Here is an example:

<display:table name="ticketList" id="ticket"> 
  <display:column title="Row Number"> 
     ${ticket_rowNum}
  </display:column> 
</display:table>

You are basically appending "_rowNum" to the variable to get the row number.

Life Goes On: LuxuryMagic #14 - Sun Certified Java Programmer 6.0!

I dedicated a past few weeks to study for the exam. I finally received the certification today! Next is Sun Certified Web Component Developer (SCWCD). In the meantime, I submitted my resumes after receiving the certification. I don't know my decision of pursing this certification rather than finding job earlier would turn out. Hopefully, I get to hear some good news but the current economy is fairly tough especially for junior level developer like me.

Life Goes On: LuxuryMagic #13 - Business Card

This business card is designed by my roommate who owns design company called Broad Sighted. I initially provided him ideas for designing LuxuryMaster.net because I wasn't very proficient on CSS during that time. I received basic lesson from him so I am a bit better now but he is really good.

He provided me excellent quality of work designing 5 different front end main pages with various color schemas depicting various mood with amazing amount of details in all places.

I will now be independently working on back-end infrastructure and I am currently planning on the whole infrastructure although I have my idea fairly solid. I remember spending a whole semester designing the architecture in school when I was working on my senior project.

Although the group of 4 spent whole semester of designing basic architecture, we ran into various issues when writing codes for the actual product. I was the team leader of the group and it was very stressful to change the implementation all the time. I learned my lesson from that and I don't plan on quick rushing on this project =)

Anyways, due to his successful performance on my LuxuryMaster.net's front end UI work, I asked him to design the business card and look how it came! I can't upload the actual version of the card because it contains personal information but if you look at it carefully, you will be able to see transparent color scheme applied in different vertical layers and it is simply amazing!

If any of you are interested getting web hosting and design services for your business, I suggest you to contact him. You may visit his website Broad Sighted for more details.

LuxuryMaster says: Engineer Yourself