Why & when a object should be created from class. Why a class can�t has static fields and method only.
everybody says in OOP ,a object should be created from a class����
In oops ,generally break the functionality in many class, as per oop standard, if I want to finish a task ,then all class should interact, here without creating a object I can finish all the task
I explain with below example then it will be more clear
Consider a table has principle amount ,period and interest rate.to calculate the functionality simply I write a method in a class to get all data from table and calculate the interest, here why I need a object creation
String is a class. I want to hold different value of string, and then I have to create more objects otherwise it not needed. String a=�w�; String h=�H�;
In ORM like hibernate, class represent the table structure so for each record o object should be created. this the scenario where object creation exactly needed.
These thing confuse me for long time. Please correct if am wrong
Remember that in Java a class is just a bunch of method and/or variables. But the actually definition of a class is: "collection of things sharing a common attribute". This definitions refers to the use of objects. However, objects are also needed as you mentioned.
You can have a class composed only of methods that can help the program to make calculations. A good example would be java.lang.Math, you don't need an object there.
Objects are primarily just another form for storing things and/or returning value to make calculations. You would have to use an object whenever the class requires lots of public/private variables.
This would obviously need objects since you're likely to implement more than 1 person in the program.
Another example would be when the class NEEDS private variables to make calculations and return values to the user:
readln() doesn't require any parameters because when you create an object you use the constructor to initialize filename. So readln() can use that variable to do whatever it must.