Chapter 9, Problem 14RE

a.

Explanation of Solution

Given:

//Create an object

Sandwich sub = new Sandwich();

//Create an object

Rectangle cerealBox = new Rectangle(5, 10, 20, 30);

//Assign null value

Edible e = null;

“e = sub;”:

The given assignment statement is legal.

Justification:

• One can convert from a class type to any interface type that the class implements...

b.

Explanation of Solution

Given:

//Create an object

Sandwich sub = new Sandwich();

//Create an object

Rectangle cerealBox = new Rectangle(5, 10, 20, 30);

//Assign null value

Edible e = null;

“sub = e;”:

The given assignment statement is illegal.

Justification:

• One can convert from a class type to any interface type that the class implements.
• Given that the class “Sandwich” implements an interface “Edible”...

c.

Explanation of Solution

Given:

//Create an object

Sandwich sub = new Sandwich();

//Create an object

Rectangle cerealBox = new Rectangle(5, 10, 20, 30);

//Assign null value

Edible e = null;

“sub = (Sandwich) e;”:

The given assignment statement is legal.

Justification:

• Given that the class “Sandwich” implements an interface “Edible”.
• “sub” is an instance variable of “Sandwich” class, and “e” is a variable of “Edible” interface...

d.

Explanation of Solution

Given:

//Create an object

Sandwich sub = new Sandwich();

//Create an object

Rectangle cerealBox = new Rectangle(5, 10, 20, 30);

//Assign null value

Edible e = null;

“sub = (Sandwich) cerealBox;”:

The given assignment statement is legal.

Justification:

• Given that the class “Sandwich” implements an interface “Edible”...

e.

Explanation of Solution

Given:

//Create an object

Sandwich sub = new Sandwich();

//Create an object

Rectangle cerealBox = new Rectangle(5, 10, 20, 30);

//Assign null value

Edible e = null;

“e = cerealBox;”:

The given assignment statement is illegal.

Justification:

• Given that the class “Sandwich” implements an interface “Edible”...

f.

Explanation of Solution

Given:

//Create an object

Sandwich sub = new Sandwich();

//Create an object

Rectangle cerealBox = new Rectangle(5, 10, 20, 30);

//Assign null value

Edible e = null;

“e = (Edible) cerealBox;”:

The given assignment statement is legal.

Justification:

• Given that the class “Sandwich” implements an interface “Edible”...

g.

Explanation of Solution

Given:

//Create an object

Sandwich sub = new Sandwich();

//Create an object

Rectangle cerealBox = new Rectangle(5, 10, 20, 30);

//Assign null value

Edible e = null;

“e = (Rectangle) cerealBox;”:

The given assignment statement is illegal.

Justification:

• Given that the class “Sandwich” implements an interface “Edible”...

h.

Explanation of Solution

Given:

//Create an object

Sandwich sub = new Sandwich();

//Create an object

Rectangle cerealBox = new Rectangle(5, 10, 20, 30);

//Assign null value

Edible e = null;

“e = (Rectangle) null;”:

The given assignment statement is illegal...