Skip to main content

Singleton Class

Using Singleton class, we allow creation of asingle object only for a given class.
How to create it??

- Make constructor private
- Create a reference of class and make it static
- Call the constructor through a function which is public and static
- put condition inside this function to call the constructor only once by checking if the reference had been initialized or not.

Note: If we have two threads accessing the same code then it's possible that we get two objects in two different threads which are competing to get that object. So we can synchronize the code snippet inside the function for assuring the creation of a single object only.
Labels:

Comments

Post a Comment

Popular posts from this blog

redis server went away

It feels really awkward to see "redis: uncaught exception: Redis server went away" when it was working and suddenly this message bumps up. I faced the same situation while accessing php redis but I guess it's more generic one, more related to redis. So, here are possible solutions that I am able to find and highlighting the one which really did work for me.

1. /usr/sbin/setsebool httpd_can_network_connect=1

By default, SELinux does not allow Apache to make socket connections. So, enable the connection.

2. Try to stop the redis server and restart it again.
either of these two should work:
a) redis-cli
b) redis server

3. There might be issues with switch, try to use different switch.
1 comment
Read more

VBA MAcro to generate "table of contents with hyperlinks" automatically in a ppt

VBA MAcro to generate "table of contents with hyperlinks" automatically in a ppt:



Function TableOfContent(count As Integer)
'count is the no. of slides in ppt
Dim var As Integer
Dim i As Integer, scount As Integer
Dim strSel As String, strTitle As String, strb As String, strtemp As String, str As String
Dim arr() As String
Dim index As Integer, indexcount As Integer, slidecount As Integer
Dim summary As Slide
Dim para As Integer
Dim slideOrder() As Integer


'To generate the Table of contents slide
ReDim slideOrder(count - 2)

'Collect all the IDs of the selected slides
For i = 1 To count - 2
slideOrder(i) = i + 2
Next

'Iterate over the slides in Index order
slidecount = UBound(slideOrder)
For scount = 1 To slidecount
If ActivePresentation.Slides(slideOrder(scount)).Shapes.HasTitle Then
'Build up the ToC Text
strTitle = ActivePresentation.Slides(slideOrder(scount)).Shapes("UseCase").TextFrame.TextRange.Text + ": "
str = ActivePresentation…
4 comments
Read more

error in eclipse on import org.eclipse.jetty.server.Server;

When you find error in line import org.eclipse.jetty.server.Server; it means eclipse doesn't contain jetty.jar. Right click on project -> properties on left pane -> java build path right pane -> add external jar under libraries tab link it to all the jar files of jetty folder. can download jetty from : http://www.eclipse.org/jetty/downloads.php now rebuild the project.
2 comments
Read more