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

Filter packets through jpcap

//Open an interface with openDevice(NetworkInterface intrface, int snaplen, boolean promics, int to_ms) JpcapCaptor captor=JpcapCaptor.openDevice(devices[index], 65535, false, 20); captor.setFilter("tcp && src port 6000", true); It'll filter all the TCP packets with source port number 6000. So, all we need to do is pass the parameters and use logical and, or operators.
16 comments
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 + ": ...
4 comments
Read more

Upload a multi-part/image/file using curl

This post is about uploading a file to server using curl. Why I'm writing this post is because of a possible bug in Postman which forced me to look for an alternative to test my upload api. Test if curl is present in system : $ which curl /usr/bin/curl If curl is not present then install it : yum (centos), apt-get (ubuntu), brew (mac) Syntax of the command : curl -F "param1=value" -F "param2=value2" -F "filecomment=file_comment" -F "image=@image_path" server_api Here's an example of the same : curl -F "user_id=12" -F "description": "desc" -F "filecomment=This is an image file" -F "image=@/Users/Desktop/testim.png" localhost:80/myblog/create If using nodeJs, you can fetch the values in fields & files parameters.
Post a Comment
Read more