Question

As in previous labs, please write the Java code for each of the following exercises in BlueJ. For each exercise, write a comment before the code stating the exercise number.

Make sure you are using the appropriate indentation and styling conventions

Exercise 1 (15 Points)

• In BlueJ, create a new project called Lab6
• In the project create a class called Company
• Add instance data (fields) for the company name (a String) and the sales for the current period (a double)
• Make sure you declare the fields with private visibility.
• Add a constructor to the Company class that accepts a parameter to set the company name and sets the sales to 0.0.

Exercise 2 (20 Points)

• Create a second class in the same project called CompanyDemo.
• Add a main method to this class. This will serve as the driver of this program.
• In main, create two Company reference variables named c1 and c2.
• Assign to those variables two Company objects, one with the name Lexcorp and the other with the name Daily Planet.
• Now print the two objects using separate println statements.
• Run the main method – you’ll see the default output when printing an object. The value returned by the default version of toString is the class name followed by a hash string created based on the memory location of this object. The displayed number is in hexadecimal – not particularly helpful.

Exercise 3 (20 Points)

• To improve the output, add a toString method to the Company class that returns a string of the form

Lexcorp made $2517.85 this period.

• To do the previous step, you need to use the String.format method. Please refer to the String API (Links to an external site.). The String.format method is the same like the prinf method. The only difference is that, the String.format method doesn't print anything to the screen. It just returns the formatted String object. Accordingly, it can be used in the toString method to return the formatted string.
• Run the main method again to see the new output, though sales for both companies will still be 0.0

Exercise 4 (10 Points)

• Add a setter (mutator) and getter (accessor) methods for the company name to the Company class.
• Add println statements (for both companies) to the main method to print just the company name
• Call the setter on one object to change the name from Lexcorp to Lexcorp, Inc.
• Then print the company name again.

Exercise 5 (20 Points)

• Add a method in Company called updateSales that accepts an integer representing the number of units sold and a double representing the unit price.
• In that method, multiply the units by the unit price and add that value to the sales.
• In main, call updateSales for c1, passing in 12 units at $24.53 per unit.
• Then call updateSales for c2, passing in 5 units at $14.17 per unit.
• Then print both company objects again.

Exercise 6 (10 Points)

• Add a second constructor to Company with an additional parameter that gives a company an initial sales figure.
• In main, change the creation of Daily Planet so that it has initial sales of $255.18.
• Rerun the main method to verify the change.

Exercise 7 (5 Points)

• Add a resetSales method in Company that resets the sales value to 0.0
• At the end of main, call resetSales just for Lexcorp and print both companies one more time.

Answer 1

Exercise 1:

class Company
{
   private String companyName;
   private double sales;
  
   public Company(String companyName)
   {
       this.companyName = companyName;
       this.sales = 0.0;
   }
  
  
}

Exercise 2:

class CompanyDemo
{
   public static void main (String[] args)
   {
       Company c1 = new Company("Lexcorp");
      
       Company c2 = new Company("Daily Planet");
      
       System.out.println(c1);
       System.out.println(c2);
      
   }
}

Output:

Company@5caf905d
Company@27716f4

Exercise 3:

public String toString()
   {
       return String.format("%s made $%.2f this period.", companyName, sales);
   }

output:

Lexcorp  made $0.00 this period.
Daily Planet   made $0.00 this period.

Exercise 4:

public void setCompanyName(String companyName)
   {
       this.companyName = companyName;
   }
   public String getCompanyName()
   {
       return companyName;
   }
  

System.out.println(c1.getCompanyName());
       System.out.println(c2.getCompanyName());
      
       c1.setCompanyName("Lexcorp, Inc.");
       System.out.println(c1.getCompanyName());
      

Output:

Lexcorp
Daily Planet
Lexcorp, Inc.

Exercise 5:

public void updateSales(int units, double price)
   {
       sales = units*price;
   }

   c1.updateSales(12,24.53);
       c2.updateSales(5,14.17);
      
       System.out.println(c1);
       System.out.println(c2);

Output:

Lexcorp, Inc.  made $294.36 this period.
Daily Planet  made $70.85 this period.

Exercise 6:

public Company(String companyName, double sales)
   {
       this.companyName = companyName;
       this.sales = sales;
   }

Company c2 = new Company("Daily Planet",255.18);

Output:

Daily Planet  made $255.18 this period.

Exercise 7:

public void resetSales()
   {
       sales = 0.0;
   }

   c1.resetSales();
      
       System.out.println(c1);
       System.out.println(c2);

Output:

Lexcorp, Inc.  made $0.00 this period.
Daily Planet  made $70.85 this period.

Complete code:

class Company
{
   private String companyName;
   private double sales;
  
   public Company(String companyName)
   {
       this.companyName = companyName;
       this.sales = 0.0;
   }
   public Company(String companyName, double sales)
   {
       this.companyName = companyName;
       this.sales = sales;
   }
  
   public String toString()
   {
       return String.format("%s made $%.2f this period.", companyName, sales);
   }
  
   public void setCompanyName(String companyName)
   {
       this.companyName = companyName;
   }
   public String getCompanyName()
   {
       return companyName;
   }
  
   public void updateSales(int units, double price)
   {
       sales = units*price;
   }
   public void resetSales()
   {
       sales = 0.0;
   }
  
}
class CompanyDemo
{
   public static void main (String[] args)
   {
       Company c1 = new Company("Lexcorp");
      
       Company c2 = new Company("Daily Planet",255.18);
      
       System.out.println(c1);
       System.out.println(c2);
      
       System.out.println(c1.getCompanyName());
       System.out.println(c2.getCompanyName());
      
       c1.setCompanyName("Lexcorp, Inc.");
       System.out.println(c1.getCompanyName());
      
       c1.updateSales(12,24.53);
       c2.updateSales(5,14.17);
      
       System.out.println(c1);
       System.out.println(c2);
      
      
       c1.resetSales();
      
       System.out.println(c1);
       System.out.println(c2);
      
   }
}

Output:

Lexcorp  made $0.00 this period.
Daily Planet  made $255.18 this period.
Lexcorp
Daily Planet
Lexcorp, Inc.
Lexcorp, Inc.  made $294.36 this period.
Daily Planet  made $70.85 this period.
Lexcorp, Inc.  made $0.00 this period.
Daily Planet  made $70.85 this period.

Do ask if any doubt. Please up-vote.