Chapter 11: Problem 40

When both a base class and a derived class have constructors, the base class's constructor is called ______________ (first/last).

Short Answer

Expert verified

Answer: When creating an instance of a derived class, the base class's constructor is called first. Then, the derived class's constructor is called.

Step by step solution

Understand base and derived classes

In object-oriented programming, a base class is a class from which other classes (derived classes) inherit properties and methods. The derived class continues to have all of its properties and methods while also owning the ones inherited from the base class.

Explain example context

Let's consider an example where we have two classes, a base class "Animal" and a derived class "Cat".

Create base class with a constructor

We will create a "Animal" class with a constructor. The constructor is a special method that is called when an object is instantiated. ``` class Animal { public Animal() { System.out.println("Animal constructor called"); } } ```

Create derived class with a constructor

Now, we will create a "Cat" class that inherits from "Animal" class and also has a constructor. ``` class Cat extends Animal { public Cat() { System.out.println("Cat constructor called"); } } ```

Instantiate the derived class and observe the constructor call order

Finally, we will create an instance of the derived class "Cat". When we do this, we will see the order in which the constructors are called. ``` public class Main { public static void main(String[] args) { Cat myCat = new Cat(); } } ``` When we run the "Main" class, the console will output: ``` Animal constructor called Cat constructor called ``` From the output, we can conclude that the base class's constructor is called #tag_answer#first#tag_answer#.

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When both a base class and a derived class have constructors, the base class's constructor is called ______________ (first/last).

Short Answer

Step by step solution

Understand base and derived classes

Explain example context

Create base class with a constructor

Create derived class with a constructor

Instantiate the derived class and observe the constructor call order

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