for循环中的乘数随着每年的变化而变化，但由于某种原因，在计算年度计算时不会应用它。现在唯一有效的乘数是当用户在提示每年复利的次数时输入值1-12。通常情况是每日，每月，每季度或每年复利。它不适用于每日。
import java.util.Scanner;
/**
This program compares CD /Investment plans input by the year
broken down by the requirements below:
This program creates a table of compound interest investment growth over time
Broken down by: a) year b) balance at end of year
Finance formula of A= P(1+ r/n)^n*t is used:
A = Future Value | P = Initial Investment
r = annual interest rate |n = times interest is compounded/year
t = years invested
*/
public class InvestmentTableFirstTest
{
public static void main(String[] args)
{
Scanner in = new Scanner(System.in);
String bestBankName = "";
double bestGrowth = 0;
boolean done = false;
while(!done)
{
System.out.print("Plan name (one word, Q to quit): ");
String bankName = in.next();
if (bankName.equals("Q"))
{
done = true;
}
else
{
System.out.print("Please enter your principal investment: ");
final double PRINCIPAL_INVESTMENT = in.nextDouble();
System.out.print("Please enter the annual interest rate: ");
double iRate = in.nextDouble();
System.out.print("Please enter number of times interest is compounded per year: ");
final double INCREMENT = in.nextDouble();
System.out.print("Enter number of years: ");
int nyears = in.nextInt();
iRate = iRate/100; System.out.println("iRate:" + iRate);
//Print the table of balances for each year
for (int year = 1; year <= nyears; year++)
{
double MULTIPLIER = INCREMENT * year;
System.out.println("Multiplier: " + MULTIPLIER); // I've included this print statement to show that the multiplier changes with each passing year
double interest = 1 + (iRate/INCREMENT);
double balance = PRINCIPAL_INVESTMENT;
double growth = balance * Math.pow(interest, MULTIPLIER);
growth = growth - PRINCIPAL_INVESTMENT;
balance = balance + growth;
System.out.printf("Year: %2d Interest Earned: $%.2f\t Ending Balance: $%.2f\n", year, growth, balance);
if (bestBankName.equals("") || bestGrowth > growth) // || bestBankName > growth
{
bestBankName = bankName; // bestBankName = bankName
bestGrowth = growth; // mostGrow = growth
}
System.out.println("Earning with this option: " + growth);
}
}
}
System.out.println("Best Growth: " + bestBankName);
System.out.println("Amount Earned: " + bestGrowth);
}
}
答案 0 :(得分：0)
这只是一个简单的错误。您正在比较(bestBankName.equals("") || bestGrowth > growth)，即如果您当前的增长（因此第一家银行集）的增长率高于第二家银行。换句话说，你翻了箭头。您需要改为if (bestBankName.equals("") || bestGrowth < growth)。
答案 1 :(得分：0)
不是一个学习机会的答案（我希望它不违反任何SO法律）。当您轻松进入设计基础时，此变体可能有助于将其视为使用简单值对象的示例。
我提出了大部分逻辑。
价值类定义＆amp; main（）：
<强> InvestmentTableFirstTest.java
import java.util.ArrayList;
import java.util.List;
import java.util.Scanner;
public class InvestmentTableFirstTest
{
public static void main(String[] args)
{
Scanner scanIn = new Scanner(System.in);
String bestBankName = "";
double bestGrowth = 0.0;
List<InvestmentOption> investmentOptions = new ArrayList<InvestmentOption>();
// some information for testing
InvestmentOption boa = new InvestmentOption("Bank of America", 5000, 1.15, 12, 5);
InvestmentOption st = new InvestmentOption("Sun Trust", 5000, 2.3, 12, 5);
InvestmentOption wf = new InvestmentOption("Wells Fargo", 5000, 5.3, 12, 5);
investmentOptions.add(boa);
investmentOptions.add(st);
investmentOptions.add(wf);
// you could wrap this with conditional logic to obtain multiple
// investment profiles from the user.
InvestmentOption userProvided = getInvestmentOptionFromUser(scanIn);
investmentOptions.add(userProvided);
// iterate over each bank in the list, evaluate growth
// and update 'best bank' if the bank being evaluated
// provides better growth than the current 'best bank'
for (InvestmentOption currentInvestmentOption : investmentOptions)
{
String bankName = currentInvestmentOption.getBankName();
double PRINCIPAL_INVESTMENT = currentInvestmentOption.getInvestment();
double iRate = currentInvestmentOption.getInterestRate() /100;
double INCREMENT = currentInvestmentOption.getCompoundPerYear();
double nyears = currentInvestmentOption.getYears();
double MULTIPLIER, interest, balance, growth = 0.0;
// calculate growth
for (int year = 1; year <= nyears; year++)
{
MULTIPLIER = INCREMENT * year;
interest = 1 + (iRate/INCREMENT);
balance = PRINCIPAL_INVESTMENT;
growth = balance * Math.pow(interest, MULTIPLIER);
growth = growth - PRINCIPAL_INVESTMENT;
}
currentInvestmentOption.setGrowth(growth);
System.out.println("Earning with " + bankName + " " + growth);
// compare earnings. If the bank being evaluated in this
// iteration provides a better investment, set it as the
// best investment option
if (currentInvestmentOption.getGrowth() > bestGrowth)
{
bestGrowth = currentInvestmentOption.getGrowth();
bestBankName = currentInvestmentOption.getBankName() ;
}
}
System.out.println("\n\nBest Growth: " + bestBankName);
System.out.println("Amount Earned: " + bestGrowth);
}
private static InvestmentOption getInvestmentOptionFromUser(Scanner in)
{
InvestmentOption iOption;
String bankName;
double principalInvestment, iRate, increment;
int nyears;
System.out.print("Plan name : ");
bankName = in.next();
System.out.print("Please enter your principal investment: ");
principalInvestment = in.nextDouble();
System.out.print("Please enter the annual interest rate: ");
iRate = in.nextDouble();
System.out.print("Please enter number of times interest is compounded per year: ");
increment = in.nextDouble();
System.out.print("Enter number of years: ");
nyears = in.nextInt();
iOption = new InvestmentOption(bankName, principalInvestment, iRate, increment, nyears);
return iOption;
}
}
<强> Investment.java
public class InvestmentOption
{
private String bankName;
private double investment;
private double interestRate;
private double compoundPerYear;
private int years;
private double growth;
public InvestmentOption(String pBankName, double pInvestment, double pInterestRate, double pCompoundPerYear, int pYears)
{
bankName = pBankName;
investment = pInvestment;
interestRate = pInterestRate;
compoundPerYear = pCompoundPerYear;
years = pYears;
}
public double getGrowth()
{
return growth;
}
public void setGrowth(double pGrowth)
{
growth = pGrowth;
}
public String getBankName()
{
return bankName;
}
public double getInvestment()
{
return investment;
}
public double getInterestRate()
{
return interestRate;
}
public double getCompoundPerYear()
{
return compoundPerYear;
}
public int getYears()
{
return years;
}
}