Singleton Design Pattern

The right way to implement a Singleton Design Pattern, also written out by researcher Bill Pugh. Two major changes to keep in mind -

1. Make the initialization as lazy as possible.
2. Get rid of the issues of synchronized access.

Way to implement -

1. Declare a public class, name it as Singleton.
2. Create a private constructor for this class.
3. Create an inner class which holds the singleton instance, make it private and static.
4. Create a Singleton instance variable in inner class make it private, static and final and load new Singleton instance.
5. Create a public static method in Singleton class to return the instance of Singleton class.

public class Singleton {
  // Private constructor prevents instantiation from other classes
  private Singleton() {}

  /**
   * SingletonHolder is loaded on the first execution of Singleton.getInstance()
   * or the first access to SingletonHolder.INSTANCE, not before.
   */
  private static class SingletonHolder {
    private static final Singleton INSTANCE = new Singleton();
  }

  public static Singleton getInstance() {
    return SingletonHolder.INSTANCE;
  }
}

Script for executing a program from windows command line

I. First set the path of the given executable home folder

SET <X VAR>=<PATH>

SET JBOSS_HOME=C:/JBOSS

II. Issue the command for executing from the shell

START cmd /C <Shell Command>

eg:
START cmd /C %JBOSS_HOME%/bin/run -c node2 -b x.y.z.a -g qaserverdomain

Rectify an issue when Airport stops working in Snow Leopard

1. Check the /var/log/system.log to see if this problem is because of a new program or updated software. See the list of daemons executing just before airport daemon startup.
2. If this problem is because of bluetooth daemons, stop the launch of bluetooth daemon by unloading the same -
sudo launchctl unload /System/Library/LaunchDaemons/com.apple.blued.plist