public static ClassName obj= new ClassName ();

Static variables are used when you don't expect the object properties to be changed frequently. When single instance of the class is required, we mark object as static.

Example would be, Let's say you have an app which syncs data to sql server periodically (off hours), in that case, you can have a static object of class (which is holding the sql connection and other stuff), and updates the data. In this case, your connection is going to be unique/unchanged as long as you point to one database and you can mark that object as static.

 

 

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