返回和抽象类？

Question

I have an Abstract class that is like:

public abstract class myClass{    

    public abstract double methodOne();
    // returns the data member value for standard deviation

    public abstract double methodTwo(String myString, int myInt);
    // returns the data member value for mean percentage

}

Then I have a class which extends this:

public class Abstract extends myClass{

    public double methodOne() {
        return 0.00;
    }

    public double methodTwo(String myString, int myInt) {
        return 20.00;   
    }    
}

Then finally I have a normal method that's return type is myClass.

public myClass anotherMethodOfMine(String myString, int myInt){

}

A simple question really, I just don't understand how a method can return another class that itself contains methods? Could someone explain it to me?

Answer 1

The method returns an object of MyClass on which you can call the methods defined there.

You should understand that a class is just a definition of behaviour and data. An object is the actual entity that can perform things with data and can invoke the behaviours defined in the class.

Answer 2

Even though your myClass can not be instantiated directly (because it's an abstract class) Abstract is a subclass of myClass ; this means it has a is a relationship.

Because of this, Abstract "is a" myClass and it can be returned as an instantiation of the parent class ( myClass ).

Answer 3

Your Method anotherMethodOfMine(String myString, int myInt) which will inturn have a object instantiated and returned to the calling function. where you can access the myclass object and use the methods which are defined in the myclass.