谁能告诉我我做错了什么。我需要从用户输入到一些 JOptionPane 输入对话框中计算一些值，然后输出答案。
如果我得到任何帮助，我将不胜感激。提前致谢!
- 输入
- 要比较的贷款数量(可以超过 1)
- 售价
- 预付款
- 对于他们想要比较的每笔贷款，您将询问以下内容
- 利率
- 年数
- 处理中
- 您需要针对给定的利率和年数计算 d 部分中列出的每种情况的每月还款额。
- 输出
- 售价
- 预付款
- 贷款金额
- 每个场景的列表
- 兴趣
- 年
- 付款
到目前为止，这是我的代码:
package javamortgagecalculator;
import javax.swing.JOptionPane;
import java.util.*;
public class JavaMortgageCalculator {
public static void main(String[] args) {
//A. Enter the Number Of Loans to compare
String numberOfLoansString = JOptionPane.showInputDialog("Enter the Number Of Loans to Compare");
//Convert numberOfLoansString to int
int numberOfLoans = Integer.parseInt(numberOfLoansString);
//B. Enter the Selling Price of Home
String sellingPriceString = JOptionPane.showInputDialog("Enter the Loan Amount");
//Convert homeCostString to double
double sellingPrice = Double.parseDouble(sellingPriceString);
//C. Enter the Down Payment on the Home
String downPaymentString = JOptionPane.showInputDialog("Enter the down payment on the Home");
double downPayment = Double.parseDouble(downPaymentString);
//Get the loanAmount by Subtracting the Down Payment from homeCost
double loanAmount = sellingPrice - downPayment;
//D. Ask the following for as many number of loans they wish to compare
//D1 Get the interest rate
double[] annualInterestRatesArray = new double[numberOfLoans];
double[] monthlyInterestRateArray = new double[numberOfLoans];
int[] numberOfYearsArray = new int[numberOfLoans];
double[] monthlyPaymentArray = new double[numberOfLoans];
double[] totalPaymentArray = new double[numberOfLoans];
int counter = 1;
for (int i=0; i < numberOfLoans; i++)
{
String annualInterestRateString = JOptionPane.showInputDialog("Enter the interest rate for Scenario " + counter);
double annualInterestRate = Double.parseDouble(annualInterestRateString);
annualInterestRatesArray[i] = (annualInterestRate);
//Obtain monthly interest rate
double monthlyInterestRate = annualInterestRate / 1200;
monthlyInterestRateArray[i] = (monthlyInterestRate);
//D2 Get the number of years
String numberOfYearsString = JOptionPane.showInputDialog("Enter the number of years for Scenario " + counter);
int numberOfYears = Integer.parseInt(numberOfYearsString);
numberOfYearsArray[i] = (numberOfYears);
//Calculate monthly payment
double monthlyPayment = loanAmount * monthlyInterestRate / (1 - 1 / Math.pow(1 + monthlyInterestRate, numberOfYears * 12));
//Format to keep monthlyPayment two digits after the decimal point
monthlyPayment = (int)(monthlyPayment * 100) / 100.0;
//Store monthlyPayment values in an array
monthlyPaymentArray[i] = (monthlyPayment);
//Calculate total Payment
double totalPayment = monthlyPaymentArray[i] * numberOfYears * 12;
//Format to keep totalPayment two digits after the decimal point
totalPayment = (int)(totalPayment * 100) / 100.0;
totalPaymentArray[i] = (totalPayment);
counter++;
}
StringBuilder sb = new StringBuilder();
for (int i = 0; i < numberOfLoans; i++) {
sb.append(String.format("\t \t \t \t \t \n", sellingPrice, downPayment, loanAmount, Arrays.toString(annualInterestRatesArray), Arrays.toString(numberOfYearsArray), Arrays.toString(monthlyPaymentArray)));
}
String toDisplay=sb.toString();
JOptionPane.showMessageDialog(null, sb.toString(), toDisplay, JOptionPane.INFORMATION_MESSAGE);
}
}
最佳答案
如果我被迫(大概是被一个伪装成编程老师的大绿色、特别丑陋的巨魔)使用多个 JOption Pane 进行输入和输出，那么我将如何解决这个问题。这仅供您引用...如果您将其作为自己的作业上交，您的老师会闻到老鼠的味道，巨魔也有谷歌。
package forums;
import javax.swing.JOptionPane;
import java.text.DecimalFormat;
/**
* Compares total cost of mortgages (aka ordinary annuity certains)
*/
public class MortgageCalculator
{
public static void main(String[] args)
{
// 1. input
final double price = Enter.aDouble("the purchase of the property");
final double deposit = Enter.aDouble("down payment");
Loan.setPrinciple(price - deposit);
int numLoans = Enter.anInteger("number of loans to compare");
Loan[] loans = new Loan[numLoans];
for ( int i=0; i<numLoans; ++i ) {
loans[i] = new Loan(
Enter.aDouble("Annual interest rate for Loan " + (i+1) + " (eg: 6.75)") / 100.0 / 12.0
, Enter.anInteger("number of years for Loan " + (i+1) + " (eg 20)") * 12
);
}
// 3. Output
final String caption =
"Principle " + Format.money(Loan.getPrinciple())
+ " = Price " + Format.money(price)
+ " - Deposit " + Format.money(deposit);
StringBuilder results = new StringBuilder(64 + numLoans * 64);
results.append("Monthly Rate, Months, Monthly Repayment, Total Repayments\n");
for ( Loan l : loans ) {
results.append(String.format("%5s, %d, %13s, %13s\n"
, Format.percent(l.rate)
, l.periods
, Format.money(l.payment())
, Format.money(l.totalPayment())
));
}
JOptionPane.showMessageDialog(null, results.toString(), caption, JOptionPane.INFORMATION_MESSAGE);
}
static class Format
{
static java.text.Format MONEY = new DecimalFormat("$#,###.##");
static String money(double amount) {
return MONEY.format(amount);
}
static java.text.Format PERCENT = new DecimalFormat("0.###%");
static String percent(double amount) {
return PERCENT.format(amount);
}
static StringBuilder join(String between, Object... values) {
StringBuilder result = new StringBuilder(values.length * 16);
if ( values.length > 0 ) {
result.append(values[0].toString());
for ( int i=1; i<values.length; ++i ) {
result.append(between)
.append(values[i].toString());
}
}
return result;
}
} // end class Format
static class Enter
{
public static int anInteger(String fieldDesc) {
return Integer.parseInt(JOptionPane.showInputDialog("Enter the "+ fieldDesc));
}
public static double aDouble(String fieldDesc) {
return Double.parseDouble(JOptionPane.showInputDialog("Enter the "+ fieldDesc));
}
} // end class Enter
} // end class MortgageCalculator
class Loan
{
private static double principle = 34324.121221312432;
final double rate;
final int periods;
static void setPrinciple(double principle) {
if (Loan.principle != 34324.121221312432)
throw new ReadOnlyException("The Principle can't be changed once set.");
Loan.principle = principle;
}
static double getPrinciple() {
return Loan.principle;
}
/**
* Initialises a new loan objects
* @param double rate The interest rate per period, as a percentage.
* eg: 0.00625 is 7.5% per annum.
* @param int periods The number of periods of the loan, typically months.
*/
Loan(double rate, int periods) {
this.rate = rate;
this.periods = periods;
}
// 2. processing
double payment() {
return principle * rate / (1 - 1/Math.pow(1+rate,periods) );
}
double totalPayment() {
return periods * payment();
}
}
class ReadOnlyException extends RuntimeException
{
private static final long serialVersionUID = 0L;
public ReadOnlyException(String message) {
super(message);
}
}
“要比较的贷款列表”由 Loan 对象数组表示...即:每个“贷款选项”由 Loan 的实例表示> 类，它将特定贷款的所有属性分组为一个整洁的“事物”，然后我们可以将其作为一个整体进行操作。这比你用来存储贷款属性的技术更好，它被称为“平行数组”......好吧，嗯，它有点过时了，事实上它有一条(油腻的)鲻鱼，它穿着(太紧)带有(藏红花粉红色)头带的橙色狩猎服……在八十年代看起来并不好看，现在，很可能会让你被殴打，被捕，或两者兼而有之；取决于您的语言环境...基本上:我们现在有更好的方法!
Loan 类还有一些方便的“计算字段”来为我们进行计算。这意味着如果我们计算还款的方式在未来由于某种原因发生变化，我们只有一个地方可以改变它，而所有使用贷款的东西(可以是读、写、排列、总计、收回，甚至是批发贷款)都可以不必找零……他们只是“免费”找零。
在这个人为设计的用例中，我们所有的贷款金额都相同，只是利率和期限不同...所以 Loan 类也有一个 static 称为“原则”的变量，它包含贷款类的所有实例的“通用”原则。该原则只能设置一次。任何后续设置原则的尝试都将导致抛出 ReadOnlyException。
无论如何，我希望您能从另一种方法中学到一些东西，以解决您在自己进行此练习时可能发现的一些子问题。对 future 的一个提示:捕获你的同学的代码进行这个练习并通读它......你可以从其他人如何处理事情中学到很多东西。
干杯。基思。
关于Java JOptionPane 输出，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/6313181/