Generic Lab

Start with the DataSet class and make it into a generic DataSetGen class. This class should load any instance of a class that implements Measurable, and no classes that do not implement Measurable. Test it with the DataSetTester.

The DataSetTester uses the BankAccount and BaseballPlayer classes. Do not change any of the classes except DataSet.

BankAccount.java

/** A bank account has a balance that can be changed by deposits and withdrawals. */ public class BankAccount implements Measurable { private double balance; /** Constructs a bank account with a zero balance. */ public BankAccount() { balance = 0; } /** Constructs a bank account with a given balance. @param initialBalance the initial balance */ public BankAccount(double initialBalance) { balance = initialBalance; } /** Deposits money into the bank account. @param amount the amount to deposit */ public void deposit(double amount) { double newBalance = balance + amount; balance = newBalance; } /** Withdraws money from the bank account. @param amount the amount to withdraw */ public void withdraw(double amount) { double newBalance = balance - amount; balance = newBalance; } /** Gets the current balance of the bank account. @return the current balance */ public double getBalance() { return balance; } public double getMeasure() { return balance; } }

BaseballPlayer.java

/** A baseball player */ public class BaseballPlayer implements Measurable { private double battingAverage; private String name; private String team; /** Constructs a baseball player with a zero batting average. */ public BaseballPlayer() { battingAverage = 0; name = ""; team = ""; } /** Constructs a baseball player with a given name, team and batting average. @param batavg the batting average @param name player's name @param team player's team */ public BaseballPlayer(String name, String team, double batavg) { battingAverage = batavg; this.name = name; this.team = team; } /** Gets the name of the player. @return the player's name */ public String getName() { return name; } /** Gets the ream of the player. @return the player's team */ public String getTeam() { return team; } /** Gets the batting average of the player. @return the batting average */ public double getBattingAverage() { return battingAverage; } public double getMeasure() { return battingAverage; } }

DataSet.java

/** Computes the average of a set of data values. */ public class DataSet { private double sum; private Measurable maximum; private int count; /** Constructs an empty data set. */ public DataSet() { sum = 0; count = 0; maximum = null; } /** Adds a data value to the data set. @param x a data value */ public void add(Measurable x) { sum = sum + x.getMeasure(); if (count == 0 || maximum.getMeasure() < x.getMeasure()) maximum = x; count++; } /** Gets the average of the added data. @return the average or 0 if no data has been added */ public double getAverage() { if (count == 0) return 0; else return sum / count; } /** Gets the largest of the added data. @return the maximum or 0 if no data has been added */ public Measurable getMaximum() { return maximum; } 

}

DataSetTester.java

/** This program tests the DataSetGen class. */ public class DataSetTester { public static void main(String[] args) { DataSetGen bankData = new DataSetGen(); bankData.add(new BankAccount(0)); bankData.add(new BankAccount(10000)); bankData.add(new BankAccount(2000)); System.out.println("Bank Account"); System.out.println("Average balance: " + bankData.getAverage()); System.out.println("Expected: 4000"); BankAccount max = bankData.getMaximum(); System.out.println("Highest balance: " + max.getBalance()); System.out.println("Expected: 10000"); DataSetGen battingAvgData = new DataSetGen(); System.out.println("Batting Averages"); battingAvgData.add(new BaseballPlayer("Derek Jeter", "New York Yankees", .323)); battingAvgData.add(new BaseballPlayer("Melky Cabria","San Fransico Giants", .346)); battingAvgData.add(new BaseballPlayer("Adrian Beltre","Texas Rangers", .319)); System.out.println("Average batting average: " + battingAvgData.getAverage()); System.out.println("Expected: .329"); BaseballPlayer maxA = battingAvgData.getMaximum(); System.out.println("Highest batting average: " + maxA.getBattingAverage() + " "+ maxA.getName() + " of the " + maxA.getTeam()); System.out.println("Expected: .346 Melky Cabria of the San Fransicso Giants"); } }

Measurable.java

/** Describes any class whose objects can be measured. */ public interface Measurable { /** Computes the measure of the object. @return the measure */ double getMeasure(); }