INHERITANCE AND POLYMORPHISM - Java Programming: From Problem Analysis to Program Design - page 651

public class SubClassSuperClassMethods //Line 1

{ //Line 2

public static void main(String[] args) //Line 3

{ //Line 4

Rectangle myRectangle1 = new Rectangle(); //Line 5

Rectangle myRectangle2 = new Rectangle(8, 6); //Line 6

Box myBox1 = new Box(); //Line 7

Box myBox2 = new Box(10, 7, 3); //Line 8

System.out.println("Line 9: myRectangle1: "
+ myRectangle1); //Line 9

System.out.println("Line 10: Area of myRectangle1: "
+ myRectangle1.area()); //Line 10

System.out.println("Line 11: myRectangle2: "
+ myRectangle2); //Line 11
System.out.println("Line 12: Area of myRectangle2: "
+ myRectangle2.area()); //Line 12

System.out.println("Line 13: myBox1: " + myBox1); //Line 13

System.out.println("Line 14: Surface Area of myBox1: "
+ myBox1.area()); //Line 14

System.out.println("Line 15: Volume of myBox1: "
+ myBox1.volume()); //Line 15

System.out.println("Line 16: myBox2: " + myBox2); //Line 16

System.out.println("Line 17: Surface Area of myBox2: "
+ myBox2.area()); //Line 17

1
0

System.out.println("Line 18: Volume of myBox2: "
+ myBox2.volume()); //Line 18

} //Line 19

} //Line 20

Sample Run:
Line 9: myRectangle1: Length = 0.0; Width = 0.0
Line 10: Area of myRectangle1: 0.0
Line 11: myRectangle2: Length = 8.0; Width = 6.0
Line 12: Area of myRectangle2: 48.0
Line 13: myBox1: Length = 0.0; Width = 0.0; Height = 0.0
Line 14: Surface Area of myBox1: 0.0
Line 15: Volume of myBox1: 0.0
Line 16: myBox2: Length = 10.0; Width = 7.0; Height = 3.0
Line 17: Surface Area of myBox2: 242.0
Line 18: Volume of myBox2: 210.0

The preceding program works as follows: The statement in Line 5 creates the Rectangle
object myRectangle1 and initializes its instance variables to 0 . The statement in Line 6
creates the Rectangle object myRectangle2 and initializes its instance variables length
and width to 8.0 and 6.0 , respectively.