Question

I have a job interview tomorrow and I’m trying to answer this question:

There is a class named C and method m in this class, this class have also empty constructor:

Main ()
{
C c = new c();

}

Class C {

public c {

//empty constructor

}

public m {

//does something - doesnt mind

}

} 

And what you have to do is to change the code so that in a creation of an instance class C, the method m would be called before the class constructor.

You have to do this without changing the main (edit only the class code).

Thanks in advance!

Answer 1

Like the other answers have said, you can make the method static. But then you need to explicitly call it. If you make a static class constructor, that will get called once automatically (you don’t need to call it), the first time the class is referenced (like when you construct the first instance). You can’t exactly control when it executes, but it will execute before the first instance is constructed. Based on the way they’ve worded the question (you can’t change the Main method), I think static class constructor is the answer they’re looking for.

http://msdn.microsoft.com/en-us/library/k9x6w0hc%28v=vs.80%29.aspx

Static constructors have the following properties:
A static constructor does not take access modifiers or have parameters.
A static constructor is called automatically to initialize the class before the first instance is created or any static members are
referenced.
A static constructor cannot be called directly.
The user has no control on when the static constructor is executed in the program.

Java doesn’t have static class constructors, but they do have static initialization blocks..

static {
    // code in here
}