Solutions to the Practice Questions

Hierarchies for Inheritance

1. The following code goes in the Rectangle class:

   public double calcDiagonalLength(){
      return Math.sqrt(width * width + length * length);
   }//calcDiagonalLength
   

2. In main method:

   Square aSquare = new Square(8);
   System.out.println("Length of diagonal: " +  aSquare.calcDiagonalLength());
   

3. In main method:

   Rectangle aRect = new Rectangle(5, 3);
   System.out.println("Length of diagonal: " + aRect.calcDiagonalLength());
   

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Setters and Getters

1. In Rectangle class:

   public void setWidth(double width){
      this.width = width;
   }
   

2. In Square class:

   public void setWidth(double width){
      this.width = width;
      this.length = width;
   }
   

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Default Constructor

1. In class Rectangle:

   public Rectangle(){
      this(1, 2);
   }
   

2. In class RightTriangle:

   public RightTriangle(){
      this(2, 5);
   }
   

3. In class Circle:

   public Circle(){
      this(1);
   }
   

A Representation to Print

1. In class Circle:

   @Override
   public String toString(){
      return getClass().getName() + " radius = " + radius;
   }
   

2. In class RightTriangle:

   @Override
   public String toString(){
      return getClass().getName() + " base = " + base + 
             " height = " + height;
   }
   

3. No code to write as toString() will be correctly inherited from the Rectangle class.

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Every Class Extends Object

[Back to Questions](chapter3:extendsObject:practice)