Chapter 9, Problem 21PP

Program Plan Intro

A method “invert()”

Program plan:

• In a file “Filter.java”, create an interface “Filter”,
  • Declare the method “accept()”.
  • Define the method “invert()”.
    • Assign the negation of the value returned from the method “accept()”.
    • Return the negated or inverted value.
• In a file “Measurer.java”, create an interface “Measurer”,
  • Declare the method “measure()”,
• In a file “BalanceFilter.java”, create a class “BalanceFilter” that implements “Filter” interface,
  • Define the method “accept()”,
    • Return the balance greater than “1000”.
• In a file “BalanceMeasurer.java”, create a class “BalanceMeasurer” that implements “Measurer” interface,
  • Define the method “measure()”,
    • Return the value obtained from the method “getBalance()”.
• In a file “BankAccount.java”, create a class “BankAccount”,
  • Declare the variable.
  • Define the constructor to create a bank account with “0” balance.
  • Define the parameterized constructor to set the specified balance.
  • Define the method “deposit()” to update the balance with the deposited amount.
  • Define the method “withdraw()” to update the balance with withdrawal amount.
  • Define the method “getBalance()” to return the current balance.
  • Define the method “addInterest()”,
    • Add the interest to the bank balance.
• In a file “Data.java”, create a class “Data”,
  • Define the method “average()”,
    • Initialize the variable.
    • Make the loop for the objects,
      • Check the condition,
        • Update sum value.
        • Increment the value of “number”.
        • • Check whether the value is positive,
            • If it is true, return the value obtained by dividing sum by the value “number”.
          • Otherwise, return “0”.
• In a file “FilterTester.java”, create a class “FilterTester”,
  • Define the method “main()”,
    • Create an array of objects for “BankAccount” class.
    • Call the constructor with “900” as parameter.
    • Call the constructor with “3000” as parameter.
    • Call the constructor with “300” as parameter.
    • Call the constructor with “5000” as parameter.
    • Call the constructor with “1000” as parameter.
    • Create an object for “BalanceMeasure”.
    • Call the method “invert()” using the object of “BalanceFilter”.
    • Print the value returned from “average()”.
    • Print the expected average value.