Question

2. 3) Compare C++ and Java:

   1. C++ uses destructors. Why does Java have no destructors?

   2. A C++ constructor must call its superclass constructor using the superclass name. A Java constructor can use the super keyword to call the superclass constructor. Why is C++ not able to use the super keyword for this purpose?

   3. In C++, is circle1 a pointer or instance after this declaration: Circle circle1;

   4. In C++, is circle1 a pointer or instance after this declaration: Circle * circle1;

   5. In Java, is circle1 a pointer or instance after this declaration: Circle circle1;

   6. If circle1 is a pointer, what line of code would cause it to point to an new instance? Write the line of code in both C++ and Java.

      C++: Java:

Answer 1

C++ uses destructors. Why does Java have no destructors?

In c++, garbage collection is programmer overhead, programmer manually has to deallocate memory, release all the memory reference.Destructor does all the work in c++. that's why it is important

But in Java, garbage collection is done by JVM, programmer does not have to worry about deallocating the memory etc.

That's why destructor is not used in java

A C++ constructor must call its superclass constructor using the superclass name. A Java constructor can use the super keyword to call the superclass constructor. Why is C++ not able to use the super keyword for this purpose?

C++ supports multiple inheritances, which means it can inherit more than one class at the same time.

when super is used to call parent class constructor it will call immediate parent class. but one c++ class can have more than one parent class. so using super can be very confusing here, that's why C++ constructor must call its superclass constructor using the superclass name

But Java does not support multiple inheritances, only one immediate parent class so using super is safe

In C++, is circle1 a pointer or instance after this declaration: Circle circle1; circle1 is an instance of class circle

In C++, is circle1 a pointer or instance after this declaration: Circle * circle1: circle1 is pointer to class Circle

In Java, is circle1 a pointer or instance after this declaration: Circle circle1: circle1 is an instance of the class Circle

If circle1 is a pointer, what line of code would cause it to point to an new instance? c++

Circle * circle1; // pointer to class Circle

Circle circle2 //instance

Circle circle3 //instance

circle1=&circle2 //pointer pointing to instance circle2

circle1=&circle3 //pointer pointing to instance circle3

In Java

There is no such thing as pointer