exercise3_27.java

java程序设计 机械工业出版社 书籍代码

import javax.swing.JOptionPane;

public class Exercise3_27 {
  public static void main(String[] args) {
    int numOfYears;
    double loanAmount;
    
    // Enter yearly interest rate
    String annualIntrestRateString = JOptionPane.showInputDialog(
      "Enter yearly interest rate, for example 8.25:");

    // Convert string to double
    double annualInterestRate = 
      Double.parseDouble(annualIntrestRateString);
    
    // Obtain monthly interest rate
    double monthlyInterestRate = annualInterestRate/1200;
    
    // Enter number of years
    String numOfYearsString = JOptionPane.showInputDialog(
      "Enter number of years as an integer, \nfor example 5:");

    // Convert string to int
    numOfYears = Integer.parseInt(numOfYearsString);
    
    // Enter loan amount
    String loanString = JOptionPane.showInputDialog( 
      "Enter loan amount, for example 120000.95:");
    
    // Convert string to double
    loanAmount =  Double.parseDouble(loanString);
    
    // Compute mortgage
    double monthlyPayment = loanAmount*monthlyInterestRate /
      (1 - (Math.pow(1 / (1 + monthlyInterestRate), numOfYears * 12)));
    
    double balance = loanAmount;
    double interest;
    double principal;
    
    System.out.println("Loan Amount: " + loanAmount);
    System.out.println("Number of Years: " + numOfYears);
    System.out.println("Interest Rate: " + annualInterestRate + "%");
    System.out.println();
    System.out.println("Monthly Payment: " + (int)(monthlyPayment * 100) / 100.0 );
    System.out.println("Total Payment: " + (int)(monthlyPayment * 12 * numOfYears * 100) / 100.0 + "\n" );

    // Display the header
    System.out.println("Payment#\tInterest\tPrincipal\tBalance");
    int i;
    for (i = 1; i <= numOfYears * 12; i++) {
      interest = (int)(monthlyInterestRate * balance * 100) / 100.0;
      principal = (int)((monthlyPayment - interest) * 100) / 100.0;
      balance = (int)((balance - principal) * 100) / 100.0;
      System.out.println(i + "\t\t" + interest
        + "\t\t" + principal + "\t\t" + balance);
    }
    
    System.exit(0);
  }
}