SavingsAccount计划

Question

即使它正在编译，我对这个程序也有点麻烦。它说我必须添加一个主要方法，但是，我这样做了，我最终得到了21个错误。有人请帮帮我..

创建一个SavingsAccount类。使用静态类变量存储每个保存器的annualInterestRate。该类的每个对象都包含一个私有实例变量savingsBalance，表示存储器当前具有的存储量。提供方法calculateMonthlyInterest通过将balanceInterestRate乘以12来计算月利息;这种兴趣应该加到savingsBalance。提供一个静态方法modifyInterestRate，它将annualInterestRate设置为一个新值。编写驱动程序来测试SavingsAccount类。实例化两个不同的savingsAccount对象，saver1和saver2，余额分别为$ 2000.00和$ 4000.00。将annualInterestRate设置为3％，然后计算每月利息并打印每个储户的新余额。然后将annualInterestRate设置为5％并计算下个月的兴趣并打印每个储户的新余额。

import java.util.Scanner;
public class SavingsAccount{

    private static double annualInterestRate;
    private double savingsBalance;

    public SavingsAccount()
    {
        savingsBalance = 0;
        annualInterestRate = 0;
    }

    public SavingsAccount(double balance)
    {
        savingsBalance = balance;
        annualInterestRate = 0;
    }

    public void calculateMonthlyInterest()
    {
        System.out.println("Current savings balance: " + savingsBalance);
        double monthlyInterest;
        monthlyInterest = (savingsBalance * annualInterestRate)/12;
        savingsBalance = monthlyInterest;
        System.out.println("New savings balance: " + savingsBalance);
    }

    public double getBalance()
    {
        return savingsBalance;
    }
    public static void modifyInterestRate(double newInterestRate)
    {
        annualInterestRate = newInterestRate;
    }
}
class Driver
{
    public static void main(String[] args)
    {
        SavingsAccount saver1 = new SavingsAccount(2000);
        SavingsAccount saver2 = new SavingsAccount(4000);
        saver1.modifyInterestRate(.03);
        saver1.calculateMonthlyInterest();
        saver2.modifyInterestRate(.03);
        saver2.calculateMonthlyInterest();
        saver1.modifyInterestRate(.05);
        saver1.calculateMonthlyInterest();
        saver2.modifyInterestRate(.05);
        saver2.calculateMonthlyInterest();
    }
}

Answer 1

您的代码运作完美。请使用SavingsAccount.java和compile使用javac SavingsAccount.java保存为run和java Driver。

我compile和run您的代码和output就是这个

Answer 2

public class SavingsAccount{

private static double annualInterestRate;
private double savingsBalance;

public SavingsAccount()
{
    savingsBalance = 0;
    annualInterestRate = 0;
}

public SavingsAccount(double balance)
{
    savingsBalance = balance;
    annualInterestRate = 0;
}

public void calculateMonthlyInterest()
{
    System.out.println("Current savings balance: " + savingsBalance);
    double monthlyInterest;
    monthlyInterest = (savingsBalance * annualInterestRate)/12;
    savingsBalance += monthlyInterest;
    System.out.println("New savings balance: " + savingsBalance);
}

public double getBalance()
{
    return savingsBalance;
}
public static void modifyInterestRate(double newInterestRate)
{
    annualInterestRate = newInterestRate;
}

}

Answer 3

您可以尝试以下代码。

package savingsaccount;


public class SavingsAccount{

    private static double annualInterestRate;
    private double savingsBalance;

    public SavingsAccount()
    {
        savingsBalance = 0;
        annualInterestRate = 0;
    }

    public SavingsAccount(double balance)
    {
        savingsBalance = balance;
        annualInterestRate = 0;
    }

    public void calculateMonthlyInterest()
    {
        System.out.println("Current savings balance: " + savingsBalance);
        double monthlyInterest;
        monthlyInterest = (savingsBalance * annualInterestRate)/12;
        savingsBalance = monthlyInterest;
        System.out.println("New savings balance: " + savingsBalance);
    }

    public double getBalance()
    {
        return savingsBalance;
    }
    public static void modifyInterestRate(double newInterestRate)
    {
        annualInterestRate = newInterestRate;
    }


    public static void main(String[] args)
    {
        SavingsAccount saver1 = new SavingsAccount(2000);
        SavingsAccount saver2 = new SavingsAccount(4000);
        SavingsAccount.modifyInterestRate(.03);
        saver1.calculateMonthlyInterest();
        SavingsAccount.modifyInterestRate(.03);
        saver2.calculateMonthlyInterest();
        SavingsAccount.modifyInterestRate(.05);
        saver1.calculateMonthlyInterest();
        SavingsAccount.modifyInterestRate(.05);
        saver2.calculateMonthlyInterest();
    }
}

Answer 4

将main方法放在SavingsAccount类中。

像这样，

public class SavingsAccount{

   private static double annualInterestRate;
    private double savingsBalance;

    public SavingsAccount()
    {
        savingsBalance = 0;
        annualInterestRate = 0;
    }

    public SavingsAccount(double balance)
    {
        savingsBalance = balance;
        annualInterestRate = 0;
    }

    public void calculateMonthlyInterest()
    {
        System.out.println("Current savings balance: " + savingsBalance);
        double monthlyInterest;
        monthlyInterest = (savingsBalance * annualInterestRate)/12;
        savingsBalance = monthlyInterest;
        System.out.println("New savings balance: " + savingsBalance);
    }

    public double getBalance()
    {
        return savingsBalance;
    }
    public static void modifyInterestRate(double newInterestRate)
    {
        annualInterestRate = newInterestRate;
    }

    public static void main(String[] args)
    {
        SavingsAccount saver1 = new SavingsAccount(2000);
        SavingsAccount saver2 = new SavingsAccount(4000);
        saver1.modifyInterestRate(.03);
        saver1.calculateMonthlyInterest();
        saver2.modifyInterestRate(.03);
        saver2.calculateMonthlyInterest();
        saver1.modifyInterestRate(.05);
        saver1.calculateMonthlyInterest();
        saver2.modifyInterestRate(.05);
        saver2.calculateMonthlyInterest();
    }
}