Alright let’s see. First you call Circle9() that starts the constructor: /** No-arg constructor */ public Circle9() { this(1.0); System.out.print(“C”); } As you can see the constructor first calls this(1.0) This means that another constructor is opened and afterwards we print “C” Alright the next Constructor is: public Circle9(double radius) { this(radius, “white”, false); System.out.print(“D”); … Read more
When an instance of Motorcycle is seen as as Vehicle, then it, quite naturally, cannot give you access to Motorcycle‘s unique properties. That’s the point of inheritance. To access them, you have to type-cast the instance: Vehicle v = new Motorcycle(); ((Motorcycle)v).MotorbikeEngineVolume = 250; When you cannot be sure the instance truly is a Motorcycle, … Read more
I figured out how to achieve the same thing by myself, even though I enjoyed the “Just learn Go” answers I got. It’s solved by creating a wrapper function userLoggedInWebEntry that takes in a WebEntryUserLoggedIn function signature, but returns a WebEntry function signature. It achieves the same thing as the Java inheritance code above, by … Read more
extends is used for inheritance and in layman term it resembles “is-a” property So class A which extends some other class B, means that “Class A is-a Class B”. And in other words Class B is a Parent of Class A. Parent class reference can hold a child object but vice-versa is not possible. Cell … Read more
Shoe roshe = new Nike(“roshe”, 11, “black”, “fashion”, 129.0, false) String literals should be enclosed in double quotes. As for your change in size type, pass int array instead of int int s[] = {11,12,13}; Shoe roshe = new Nike(“roshe”, s, “black”, “fashion”, 129.0, false) or Shoe roshe = new Nike(“roshe”,new int[]{11, 12, 13} , … Read more
I suspect that the code you are looking at was written to demonstrate how pointers to base classes can be used with objects of derived classes. No, pointers are not necessary for the functionality of this learning exercise. In fact, that is probably the reason this functionality was chosen. Since you see how to accomplish … Read more
I have changed your code. Problem was: findViewById(). Activity already have findViewById() method so you can call it in Activity. But Fragment don’t have this method. In Fragment you have to find a View by View.findViewById() method, here View will be the view you are inflating in onCreateView() new ViewPagerAdapter(this). To create a View you … Read more
The Serializable interface does nothing by itself, it is merely, as you remarked, a marker interface to show Java that this particular class is serializable. That means that if you denote a class with this interface, all child classes will be treated as serializable by themselves (just like normal inheritance), but the task of a … Read more
Since this is clearly a homework exercise, it is not appropriate for me to provide an answer directly. Instead, I have written a little program for you to demonstrate what the question means, and running it will provide an answer. You can try this out for yourself: public class Main { class A {} class … Read more
AAA ref1 = new CCC(); BBB ref2 = new CCC(); CCC ref3 = new CCC(); Is there anyone who can explain how it works inside the complier? In this case ref1 is a reference to a AAA object and since CCC inherits from AAA it is also an AAA so this assignment is allowed by … Read more
that’s is because your eat function print to the stdout and does not return a string. you need to change your eat function to be: def eat(self): return “eats well” 1 solved How can I use the info from the parent class in a child object? [closed]
What I think you’re trying to achieve is that when you call your method “horn” with some parameter it has to either use “Beep!” or “Boop!”. First of: void horn(a,b) Is not a valid function signature in Java, in a java function you always have to specify what type the input you’re providing is. In … Read more
The rule of thumb on assigning an object of one type to a reference of another type is the “isA” test. If your super class is Fruit and subclass is Banana, you can assign: Fruit obj = new Banana() if Banana isA Fruit. I suggest you get a good understanding on inheritance and type system … Read more
If u really dont want to inherit a class,then just make its member variables and member functions as private ,if other class tries to inherit it they cant have access to its funtions and variables anyways. But using final is a better option 1 solved Is there any way to restrict inheritance? [closed]
goto File > New > File or use shortcut key (COMMAND+N) Select Cocoa Touch Class Enter Class Name AddCommentsViewController Select Subclass of UIViewController Press Next and then press create. A new Cocoa Touch class named AddCommentsViewController is created inherit from UIViewController solved What is inheriting in swift 4