GitHub Frequently Used Tips and Tricks

Adding an Existing project to GitHub

1. Create a new repository(repo) on GitHub.
   
2. In command prompt open Git Bash
3. Change the current working directory to your local project.
4. Initialize the local directory as a Git repository.
git init

5. Add (stage) the files in your new local repository.
git add .

6. Commit staged files locally.
git commit -m "initial commit"

7. In GitHub copy the https url of your newly created repo (e.g https://github.com/xxxxxxx.git)
   
8. In the command prompt, add the URL for the remote repository where your local repository will be pushed.
git remote add origin https://github.com/xxxxxxx.git
   
git remote -v

9. Push the changes in your local repository to GitHub.
   git push -f origin master

GlassFish 4.0 ClassCastException on Class with the Same Type

Repeated deploy and undeploy of applications in GlassFish you may encounter the following class loader issue.

java.lang.ClassCastException: my.com.Test cannot be cast to my.com.Test

Within the GlassFish administration console:

Disable and Undeploy the application.
Restart the server.
Deploy the application.

Using Reload or Redeploy will not resolve the issue.

Mac OSX Tips

Setting JAVA_HOME

OSX: 10.9.3

Open a Terminal

Type: nano .bash_profile

Add: export JAVA_HOME=$(/usr/libexec/java_home)

Exit nano: ctrl+o and hit return

Type: source .bash_profile

Type:  echo $JAVA_HOME

You should see something like: Library/Java/JavaVirtualMachines/jdk1.7.0_60.jdk/Contents/Home

Ripple Emulator: 500 Internal Server Error on localhost connections

I'm trying to develop a mobile app using Cordova (PhoneGap). To test this app I have been using Ripple this is a great tool and much more convenient than the slow Android emulator. One problem I did came across was a 500 Internal Server Error while trying to connect to another server running locally on my computer. This is the http headers and response.

Headers:
Request URL:

https://rippleapi.herokuapp.com/xhr_proxy?tinyhippos_apikey=ABC&tinyhippos_rurl=http%3A//localhost%3A8080/xxxxxxxx/login/authenticateMobileUser

Request Method:

POST

Status Code:

500 Internal Server Error

Response:
{

  "code": "ECONNREFUSED",

  "errno": "ECONNREFUSED",

  "syscall": "connect"

}

To fix this problem - Ripple emulator by default has "Cross Domain Proxy" set to "Remote". For localhost connections change it to "Local".

Glassfish 3.1 Problems - "Attempting to execute an operation on a closed EntityManagerFactory"

Recently I tried to re-deploy a EJB jar application into the GlassFish 3.1 Server but got the following error:

java.lang.IllegalStateException: Attempting to execute an operation on a closed EntityManagerFactory.

To fix this problem do a clean deploy by first undeploying the application and redeploying the application.

Eclipse: How to convert a Java Project into a Web Project

Eclipse Version: Helios Service Release 1

Java projects do not have the Export->WAR File option. To get this option you must convert your Java project into a web project.

Step 1: Create a new Dynamic Web Project
Step 2: Open the Dynamic Web Projects .project file and copy the following lines of XML to your Java projects .project file.

[2011-06-15 14:01:36 - ddms]null

<buildspec>
...
<buildcommand>   <name>org.eclipse.wst.common.project.facet.core.builder</name>
<arguments>
</arguments>
</buildCommand>
...
</buildSpec>

<natures>
...
<nature>org.eclipse.wst.jsdt.core.jsNature</nature>
...
</natures>

Step 3: Within the Java projects Project Facets enable the Dynamic Web Module and Java.

Android Programming: ddms]null java.lang.NullPointerException error

Starting Android emulator within Eclipse Helios I get:

[2011-06-15 14:01:36 - ddms]null
java.lang.NullPointerException
at com.android.ddmlib.Client.sendAndConsume(Client.java:572)
at com.android.ddmlib.HandleHello.sendHELO(HandleHello.java:142)
at com.android.ddmlib.HandleHello.sendHelloCommands(HandleHello.java:65)
at com.android.ddmlib.Client.getJdwpPacket(Client.java:671)
at com.android.ddmlib.MonitorThread.processClientActivity(MonitorThread.java:317)
at com.android.ddmlib.MonitorThread.run(MonitorThread.java:263)
}

To fix this problem set a Size on the SD card property within the Android Virtual Device (AVD).