Question

Consider the following classes:

Dollhouse, Legos, TeddyBear, Toy, ToyBox

Which should not be included in a class hierarchy?

  

ToyBox

   

Dollhouse

   

TeddyBear

   

Legos

   

Toy

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Questions 6 - 9 Refer to the following code:

public class WhatsIt {
    private int[] values;
    private double average;

    public WhatsIt () {
        values = new int[10];
        findAvg();
    }

    public WhatsIt (int[] n) {
        values = n;
        findAvg();
    }

    public void findAvg () {
        double sum = 0;
        for (int i =  0; i < values.length; i++) {
            sum += values[i];
        }
        average = 1.0 * sum / values.length;
    }

    public String toString() {
        return "Average: " + average + " Length: " + values.length;
    }
}

What does the line findAvg(); in the constructor do?

  

Creates a reference to the average variable.

   

Calls the constructor findAvg; so the object can be created in memory.

   

This call should be removed.

   

Checks to see if the average variable has been initialized.

   

Calls the method findAvg() so the variable average is updated correctly.

Answer 1

1) Legos ,Teddy Bear and DollHouse are all kinds of Toys so they should be child of class Toy . ToyBox should not be included in the class hierarchy.

2)The method findAvg() is called so that the variable average gets updated everytime the constructor is called or object is created.