exercise_1_2

package y2kmz.com.daikuan;//说明程序出现的类在该包中

import javax.swing.JOptionPane;//导入javax.swing这个包中的JOptionPane这个类

public class exercise_1_2 {//公共类exercise
public static void main(String[] args) {
// Enter yearly interest rate
String annualIntrestRateString = JOptionPane.showInputDialog(
"输入利率，如 8.11：");//输入String类型的变量annuealInterstRateString（年利率）

// Convert string to double
double annualInterestRate =
Double.parseDouble(annualIntrestRateString);//annualInterestRate，利率
//将String类型变量annualInterestRate转换为Double型变量（）
// Obtain monthly interest rate
double monthlyInterestRate = annualInterestRate/1200;
//月利率等于年利率除以1200
// Enter number of years
String numOfYearsString = JOptionPane.showInputDialog(
"输入贷款年限, /n如 5：");//贷款年限，numOfYearsString
//输入String类型的numOfYearsString（贷款年限）
// Convert string to int
int numOfYears = Integer.parseInt(numOfYearsString);
//将String类型变量numOfYears转换成Int类型

String investmentAmountString = JOptionPane.showInputDialog(
"输入贷款总额, 如 120000.00:");//investmentAmountString，贷款总额
//输入String类型变量investmentString(贷款总量)
// Convert string to double
double investmentAmount =  Double.parseDouble(investmentAmountString);
//将字符串类型的贷款总量转换成双精度浮点型
double futureValue = (investmentAmount * monthlyInterestRate)
/(1-1/Math.pow((1+monthlyInterestRate),(numOfYears*12)));
//double类型futureValue=******

JOptionPane.showMessageDialog(new JOptionPane(), "月偿还金额："+((int)(futureValue * 100) / 100.0)+"  总偿还金额："+((int)(futureValue * 12 * numOfYears * 100) / 100.0));
//输出

System.exit(0);//程序结束
}
}