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Program listing

// Copyright (C) 1998-2016 Davin Pearson
// Website:

class Citizen
   // Properties of the class...
   private String name;
   private int    salary;
   private int    savings;
   private int    loan;

   // Constructor of the class...
   public Citizen(String aName, int aSalary, int aSavings, int aLoan)
      name    = aName;
      salary  = aSalary;
      savings = aSavings;
      loan    = aLoan;

   // Methods of the class...
   public int getSalary()
      return salary;
   public void setSalary(int aSalary)
      salary = aSalary;

class Government
   public static int money;
   public static int numBattleships;

class CitizenTest
   // The main method is the point of entry into the program...
   public static void main(String[] args)
      Citizen e = new Citizen("Ernie", 50000, 2000,   0);
      Citizen b = new Citizen("Bert", 100000,10000,5000);

      System.out.println("Ernie's salary is: " + e.getSalary());


// (1) Write a method isRich that has no arguments and
// returns a boolean value as to whether or not the current
// person has more that $50,000 in savings. Add some code
// to the main method to test if Ernie is rich.

// HINT: Look at the getSalary method to see how to write a
// method that has no arguments and returns a value.
// (2) Write a "salaryRise" method that has one int
// parameter called "amount" which increases the person's
// salary by that amount.  Add some code to the main method
// to raise Ernie's salary by $10,000.

// HINT: Look at the setSalary method to see how to write a
// method with one parameter.
// (3) Write a "netWorth" method that returns the difference
// of the person's savings and their loan.  Then put some
// code in the main method to print out Ernie's net worth.
// (4) If we take away the "System.out.println( )" method
// call from the line that says: "e.getSalary()", then
// nothing is printed to the screen when we run it.  If we
// don't use the value returned by the call to getSalary,
// then why does Java even allow this code to compile?
// (5) Write a "toString" method that has no parameters and
// returns a string containing all the information about the
// citizen, including their name, salary, savings and their
// loan, if they have one.  Put a some code into the main
// method to test it out.
// Classes often have a toString method and you will learn
// more about this later.

// HINT: Use the "+" operator to build up a String object
// and return this object at the end of the method.

// (6) Next to the constructor, write a second constructor
// that has one String parameter called "aName".  Make it so
// that the constructor sets the person's name to aName and
// sets every other property to zero dollars.  Add the
// following line of code to the main method to test out
// this second constructor that you have just written:

//  Citizen f = new Citizen("Fred");

// NOTE: Having more than one constructor in a class is an
// example of overloading.  You can overload any method, not
// just the constructor, by having several methods all with
// the same name but different parameters and in the same
// class.
// (7) Write the Citizen method: public void paySalary()
// that adds the person's salary to their savings, less 10%
// tax.  Call paySalary from the main method on Ernie
// and Bert and verify that it works.
// (8) Alter the paySalary method so that the Government's
// "money" property goes up by the amount of tax that was
// charged on the citizen.
// HINT: How do you access a static property?
// (9) Write a method public static void buyBattleships()
// in the Government class that causes the Government to buy
// as many battleships as it can afford, without going in
// debt.  Each battleship costs $42,000 each.  Remember to
// adjust both properties "money" and "numBattleships".
// (10) Call buyBattleships from the main method.
// HINT: How do you call a static method?
// (11) HARDER: Why is everything in the Government class
// labelled as static?