Question

Write a line of code that indicates to the compiler that the method being declared overrides a superclass method.

Write a line of code that specifies that class Fly inherits from class Insect.

Call superclass Insect's toString method from subclass Fly's tostring method.

Call superclass Insect's constructor from subclass Fly's constructor, assume that the constructor receives an integer for number of legs and a string for the ability it has.

Answer 1

For each problem given, the solution is provided below:

The line that shows the superclass method overrides in the derived class. The line is in bold form.

public class A{

public double compute_cost()

{

    return 50.0;

}

}

public class B extends A{

//The function of Base class

//A overrides in the derived class B.

public double compute_cost()

{

    return 55.0;

}

}

Explanation:

• Consider a class that represents the Base class and the class B that is derived by class A.
• The function compute_cost() is the function of the base class A which is override in the derived class B.

The line of code that specifies that class Fly inherits from class Insect is as follows:

The line is in bold form.

public class Insect{

//Body of class Insect.

}

public class Fly extends Insect{

    //Body of class Fly.

   

}

Explanation:

• The base class is Insect and the derived class is Fly class. The Fly inherits from class Insect.
• For inheritance, the extend keyword is used in the derived class.

The calling of superclass Insect's toString method from subclass Fly's tostring method is as follows:

public class Insect{

public String toString()

{

    return("Base class Insect toString() method.");

}

}

public class Fly extends Insect{

@Override

//The toString() function of class Insect

//is called in the dervied class.

public String toString()

{

    return (super.toString());

}

}

Explanation:

• The Base class Insect has a method named as toString() that return the string as Base class Insect toString() method.
• The method toString() of Base class is called in the subclass Fly by using the super keyword.
• For calling the methods of the superclass, super keyword is used.

The calling of superclass Insect's constructor from subclass Fly's constructor. The code is provided below:

public class Insect{

//Declare the variables.

public int legs_count ;

public string ability;

//Parameterized constructor of the class Insect.

public Insect(int legs, string ability)

{

    //Assign the values.

    legs_count = legs;

    ability = ability;

}

}

public class Fly extends Insect{

//Constructor of derived class Fly.

public Fly(int legs, string insect_ability)

{

    //Calling of the parameterized constructor of

    //the base class Insect.

    super(legs, insect_ability);

}

}

Explanation:

• The calling of the Base class methods, constructors is called by the keyword super.
• The line super(legs, insect_ability) call the parameterized constructor of the class Insect.